Version 2.0.1

Because the current threshold(10.0) makes it hard to remove a panel.

Resolve #389

.gitignore

@@ -17,6 +17,7 @@ DerivedData/
 *.perspectivev3
 !default.perspectivev3
 xcuserdata/
+IDEWorkspaceChecks.plis
 
 ## Other
 *.moved-aside

.swiftformat

@@ -0,0 +1,3 @@
+--header "// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license."
+--disable andOperator,anyObjectProtocol,blankLinesAroundMark,blankLinesAtEndOfScope,blankLinesAtStartOfScope,blankLinesBetweenScopes,braces,consecutiveBlankLines,consecutiveSpaces,duplicateImports,elseOnSameLine,emptyBraces,hoistPatternLet,indent,isEmpty,leadingDelimiters,linebreakAtEndOfFile,linebreaks,numberFormatting,ranges,redundantBackticks,redundantBreak,redundantExtensionACL,redundantFileprivate,redundantGet,redundantInit,redundantLet,redundantLetError,redundantNilInit,redundantObjc,redundantParens,redundantPattern,redundantRawValues,redundantReturn,redundantSelf,redundantVoidReturnType,semicolons,sortedImports,spaceAroundBraces,spaceAroundBrackets,spaceAroundComments,spaceAroundGenerics,spaceAroundOperators,spaceAroundParens,spaceInsideBraces,spaceInsideBrackets,spaceInsideComments,spaceInsideGenerics,spaceInsideParens,specifiers,strongOutlets,strongifiedSelf,todos,trailingClosures,trailingCommas,trailingSpace,typeSugar,unusedArguments,void,wrapArguments,yodaConditions
+

.travis.yml

@@ -2,12 +2,6 @@ language: objective-c
 branches:
   only:
     - master
-cache:
-  directories:
-  - /usr/local/Homebrew
-  - $HOME/Library/Caches/Homebrew
-before_cache:
-  - brew cleanup
 env:
   global:
   - LANG=en_US.UTF-8
@@ -15,55 +9,64 @@ env:
 jobs:
   include:
   - stage: "Builds"
-    osx_image: xcode9.4
-    script: xcodebuild -scheme FloatingPanel SWIFT_VERSION=4.1 clean build
-    name: "Swift 4.1"
-  - script: xcodebuild -scheme FloatingPanel SWIFT_VERSION=4.2 clean build
-    osx_image: xcode10
-    name: "Swift 4.2"
-  - script: xcodebuild -scheme FloatingPanel SWIFT_VERSION=5.0 clean build
-    osx_image: xcode10.3
-    name: "Swift 5.0"
-  - script: xcodebuild -scheme FloatingPanel SWIFT_VERSION=5.1 SUPPORTS_MACCATALYST=NO clean build
+    script: xcodebuild -scheme FloatingPanel SWIFT_VERSION=5.1 SUPPORTS_MACCATALYST=NO clean build
     # SUPPORTS_MACCATALYST=NO because Xcode 11 runs on macOS 10.14 in Travis CI
-    osx_image: xcode11
+    osx_image: xcode11.3
     name: "Swift 5.1"
+  - script: xcodebuild -scheme FloatingPanel SWIFT_VERSION=5.2 clean build
+    osx_image: xcode11.6
+    name: "Swift 5.2"
+  - script: xcodebuild -scheme FloatingPanel SWIFT_VERSION=5.3 clean build
+    osx_image: xcode12
+    name: "Swift 5.3"
 
   - stage: "Tests"
-    osx_image: xcode10.3
-    script: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=10.3.1,name=iPhone SE'
+    script: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=10.3.1,name=iPhone SE (1st generation)'
+    osx_image: xcode11.6
     name: "iPhone SE (iOS 10.3)"
   - script: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=11.4,name=iPhone 7'
-    osx_image: xcode10.3
+    osx_image: xcode11.6
     name: "iPhone 7 (iOS 11.4)"
-  - script: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=12.2,name=iPhone X'
-    osx_image: xcode10.3
-    name: "iPhone X (iOS 12.2)"
-  - script: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=13.0,name=iPhone 11'
-    osx_image: xcode11
-    name: "iPhone X (iOS 13.0)"
+  - script: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=12.4,name=iPhone X'
+    osx_image: xcode11.6
+    name: "iPhone X (iOS 12.4)"
+  - script: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=13.6,name=iPhone 11'
+    osx_image: xcode11.6
+    name: "iPhone X (iOS 13.6)"
 
-  - stage: Build examples
-    osx_image: xcode11
-    script: xcodebuild -scheme Maps -sdk iphonesimulator clean build
+  - stage: "Build examples"
+    osx_image: xcode11.6
+    script: xcodebuild -workspace FloatingPanel.xcworkspace -scheme Maps -sdk iphonesimulator clean build
     name: "Maps"
-  - script: xcodebuild -scheme Stocks -sdk iphonesimulator clean build
-    osx_image: xcode11
+  - script: xcodebuild -workspace FloatingPanel.xcworkspace -scheme Stocks -sdk iphonesimulator clean build
+    osx_image: xcode11.6
     name: "Stocks"
-  - script: xcodebuild -scheme Samples -sdk iphonesimulator clean build
-    osx_image: xcode11
+  - script: xcodebuild -workspace FloatingPanel.xcworkspace -scheme Samples -sdk iphonesimulator clean build
+    osx_image: xcode11.6
     name: "Samples"
+  - script: xcodebuild -workspace FloatingPanel.xcworkspace -scheme SamplesObjC -sdk iphonesimulator clean build
+    osx_image: xcode11.6
+    name: "SamplesObjC"
 
-  - stage: Carthage
-    osx_image: xcode11
+  - stage: "Swift Package Manager"
+    script: swift build -Xswiftc "-sdk" -Xswiftc "`xcrun --sdk iphoneos --show-sdk-path`" -Xswiftc "-target" -Xswiftc "arm64-apple-ios13.0"
+    osx_image: xcode11.6
+    name: "iPhone OS"
+  - script: swift build -Xswiftc "-sdk" -Xswiftc "`xcrun --sdk iphonesimulator --show-sdk-path`" -Xswiftc "-target" -Xswiftc "x86_64-apple-ios13.0-simulator"
+    osx_image: xcode11.6
+    name: "iPhone Simulator"
+
+  - stage: "Carthage"
+    # Carthage doesn't fix the issue with Xcode 12: https://github.com/Carthage/Carthage/releases/tag/0.36.0
+    osx_image: xcode11.6
     before_install:
     - brew update
     - brew outdated carthage || brew upgrade carthage
     script:
     - carthage build --no-skip-current
 
-  - stage: CocoaPods
-    osx_image: xcode11
+  - stage: "CocoaPods"
+    osx_image: xcode11.6
     before_install: 
     - gem install cocoapods
     script:

Documentation/FloatingPanel 2.0 Migration Guide.md

@@ -0,0 +1,294 @@
+# FloatingPanel 2.0 Migration Guide
+
+FloatingPanel 2.0 is the latest major release of FloatingPanel. As a major release, following Semantic Versioning conventions, 2.0 introduces API-breaking changes.
+
+This guide is provided in order to ease the transition of existing applications using FloatingPanel 1.x to the latest APIs, as well as explain the design and structure of new and updated functionality.
+
+## Updated Minimum Requirements
+
+* Swift 5.0
+* iOS 11 (iOS 10 is still the deployment target, but not tested well)
+* Xcode 11.0
+
+## Benefits of Upgrading
+
+* __Top, left and right positioned panel__
+  * FloatingPanel is not just a library for a bottom positioned panel, but also top, left and right positioned ones.
+* __Objective-C compatibility__
+  * The entire APIs are exposed in Objective-C. So you can use them in Objective-C directly.
+* __Flexible and explicit layout customization__
+  * `FloatingPanelLayout` is redesigned. There is no implicit rules to lay out a panel anymore.
+* __New spring animation without UIViewPropertyAnimator__
+  * The new spring animation uses [Numeric springing](http://allenchou.net/2015/04/game-math-precise-control-over-numeric-springing/) which is a very powerful tool for procedural animation. Therefore a library consumer is easy to modify a panel behavior by 2 paramters of the deceleration rate and response time.
+* __Handle the panel position anytime__
+  * `floatingPanelDidMove(_:)` delegate method is also called while a panel is moving. The method behavior becomes same as `scrollViewDidScroll(_:)` in `UIScrollViewDelegate`. And in the method a library consumer is able to change a panel location.
+* __Update the removal interaction's invocation__
+  * Now you can invoke the removal interaction at any time where you want. There is no restrictions in the library.
+* __Fix many issues depending on API design__
+  * See the following sections for details.
+
+## API Name Changes
+
+* `FloatingPanelPosition` is now `FloatingPanelState`.
+  * `FloatingPanelPosition` in v2 is used to specify a panel position(top, left, bottom and right) in a screen.
+* `FloatingPanelSurfaceView` is `SurfaceView` only in Swift.
+* `FloatingPanelBackdropView` is `BackdropView` only in Swift.
+* `FloatingPanelGrabberHandleView` is `GrabberView` only in Swift.
+* "decelerate" term is replaced with "attract" because the panel's behavior is not unidirectional, but going back and forth so that it is settled to a location.
+
+## `FloatingPanelController`
+
+* `layout` and `behavior` properties can be changed directly without using the delegate methods.
+
+```swift
+fpc.behavior = SearchPaneliPadBehavior()
+fpc.layout = SearchPaneliPadLayout()
+fpc.invalidateLayout() // If needed
+```
+
+* The second argument of `addPanel(toParent:)` changes to specify an index of subviews of a view in which a panel is added.
+
+```diff
+- public func addPanel(toParent parent: UIViewController, belowView: UIView? = nil, animated: Bool = false) {
++ public func addPanel(toParent parent: UIViewController, at viewIndex: Int = -1, animated: Bool = false) {
+```
+
+* `surfaceOriginY` is now `surfaceLocation`.
+* `updateLayout` is now `invalidateLayout`.
+* The scroll tracking API is changed a bit to support multiple scroll view tracking in the future.
+  * Now `untrack(scrollView:)` is used to disable the scroll tracking.
+
+## `FloatingPanelControllerDelegate`
+
+* `floatingPanelDidEndDragging(_ vc:willAttract:)` is added to check whether a panel will continue to move after dragging.
+* `floatingPanelDidMove(_:)` behavior changes. The method is also called in the spring animation.
+* The removal interaction delegate is updated.
+  * `floatingPanel(_:shouldRemoveAt:with:)` is added to determine whether it invokes the removal interaction in any state.
+  * `floatingPanelWillRemove(_:)` is added.
+* `floatingPanel(_: FloatingPanelController, layoutFor size: CGSize)` is added to respond to a layout change in regular size classes on iPad.
+
+```swift
+func floatingPanel(_ fpc: FloatingPanelController, layoutFor size: CGSize) -> FloatingPanelLayout {
+    if aCondition(for: size) {
+        return SearchPanelLayout()
+    }
+    return SearchPanel2Layout()
+}
+```
+
+* The `targetState` argument type of `floatingPanelWillEndDragging(_:withVelocity:targetState:)` is changed from `FloatingPanelState` to  `UnsafeMutablePointer<FloatingPanelState>` to modify a target state on demand.
+
+```swift
+func floatingPanelWillEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetState: UnsafeMutablePointer<FloatingPanelState>) {
+    switch targetState.pointee {
+        case .full:
+          // do something...
+        case .half:
+            if aCondition {
+                targetState.pointee = .tip
+            }
+        default:
+            break
+    }
+}
+```
+
+### Deprecated APIs
+
+* `floatingPanel(_:behaviorFor:)`
+  * Please update `FloatingPanelController.behavior` directly.
+* `floatingPanel(_:shouldRecognizeSimultaneouslyWith:)`
+  * Please use `FloatingPanelController.panGestureRecognizer.delegateProxy`.
+
+## `FloatingPanelLayout`
+
+* `position` property is added to determine a panel position.
+* `initialPosition` is now `initialState`.
+* `supportedPositions` and `insetFor(position:)` are replaced with `anchors` property.
+* `backdropAlphaFor(position:)` is now `backdropAlpha(for:)`.
+
+```swift
+class SearchPanelPadLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition  = .top
+    let initialState: FloatingPanelState = .tip
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            ...
+        ]
+    }
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return 0.3
+    }
+    ...
+}
+```
+
+### New `FloatingPanelLayoutAnchoring` classes
+
+The following objects adopting `FloatingPanelLayoutAnchoring` protocol are added to configure the flexible and explicit layout.
+
+#### `FloatingPanelLayoutAnchor`
+
+This class is used to specify a panel layout using insets from a rectangle area of the superview or safe area.
+
+* `FloatingPanelFullScreenLayout` is replaced with anchors using `.superview` reference guide.
+* `FloatingPanelLayoutAnchor(fractionalInset:edge:referenceGuide:)` lets you lay out a panel at a relative position in a reference rectangle area.
+
+```swift
+// Before:
+class MyPanelLayout: FloatingPanelLayout {
+    var initialPosition: FloatingPanelPosition {
+        return .half
+    }
+
+    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
+        switch position {
+        case .full: return 16.0
+        case .half: return 262.0
+        case .tip: return 44.0
+        case .hidden: return nil
+        }
+    }
+}
+
+// After:
+class MyPanelLayout: FloatingPanelLayout {
+    var position: FloatingPanelPosition = .bottom
+    var initialState: FloatingPanelState { .half }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .superview),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
+    }
+}
+```
+
+#### `FloatingPanelIntrinsicLayoutAnchor`
+
+This class is used to specify a panel layout using offsets from the intrinsic size layout.
+
+* This replaces `FloatingPanelIntrinsicLayout`.
+* This is also able to configure a fractional layout in the intrinsic size.
+
+```swift
+// Before:
+class MyPanelIntrinsicLayout: FloatingPanelIntrinsicLayout {
+    var initialPosition: FloatingPanelPosition {
+        return .half
+    }
+    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
+        switch position {
+        case .full: return 16.0
+        case .half: return 262.0
+        case .tip: return 44.0
+        case .hidden: return nil
+        }
+    }
+}
+
+// After:
+class MyPanelIntrinsicLayout: FloatingPanelLayout {
+    var position: FloatingPanelPosition = .bottom
+    var initialState: FloatingPanelState { .full }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 16.0, referenceGuide: .safeArea),
+            .half: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.5, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
+    }
+}
+```
+
+### Deprecated APIs
+
+* `.topInteractionBuffer` and `.bottomInteractionBuffer`.
+  * Please control the max/min range of the motion in `floatingPanelDidMove(_:)` delegate method as below.
+
+```swift
+func floatingPanelDidMove(_ fpc: FloatingPanelController) {
+    if fpc.isAttracting == false {
+        let loc = fpc.surfaceLocation
+        let minY = fpc.surfaceLocation(for: .full).y - 6.0
+        let maxY = fpc.surfaceLocation(for: .tip).y + 6.0
+        fpc.surfaceLocation = CGPoint(x: loc.x, y: min(max(loc.y, minY), maxY))
+    }
+}
+```
+
+## `FloatingPanelBehavior`
+
+* `.springDecelerationRate` and `.springResponseTime` properties are added to control the new spring effect of Numeric springing.
+
+### Deprecated APIs
+
+* `addAnimator(_:to:)`, `removeAnimator(_:from:)`
+  * They are moved into `floatingPanel(_:animatorForPresentingTo:)` and  `floatingPanel(_:animatorForDismissingWith:)` of `FloatingPanelControllerDelegate` because they are used for view transitions.
+* `interactionAnimator(_:to:with:)`, `moveAnimator(_:from:to:)`
+  * They are removed because the animators are replaced with the new spring effect.
+* `removalVelocity`, `removalProgress`
+  * They are replaced with `floatingPanel(_:shouldRemoveAt:with:)` of `FloatingPanelControllerDelegate`
+* `removalInteractionAnimator(_:with:)`
+  * It is integrated with `floatingPanel(_:animatorForDismissingWith:)` of `FloatingPanelControllerDelegate`.
+
+## `SurfaceView`
+
+* `SurfaceAppearance` class and `SurfaceView.appearance` property are added to specify the rounding corners, shadows and background color.
+  * `SurfaceView.appearance` property avoids `Ambiguous use of 'cornerRadius'` error, for instance.
+  * `SurfaceAppearance` enables to apply layered box shadows into a surface to materialize it.
+
+```swift
+// Before:
+fpc.surfaceView.cornerRadius = 6.0
+fpc.surfaceView.backgroundColor = .clear
+fpc.surfaceView.shadowHidden = false
+fpc.surfaceView.shadowColor = .black
+fpc.surfaceView.shadowOffset = CGSize(width: 0, height: 16)
+fpc.surfaceView.shadowRadius = 16.0
+
+// After:
+let appearance = SurfaceAppearance()
+appearance.cornerRadius = 8.0
+appearance.backgroundColor = .clear
+
+let shadow = SurfaceAppearance.Shadow()
+shadow.color = .black
+shadow.offset = CGSize(width: 0, height: 16)
+shadow.radius = 16
+shadow.spread = 8
+appearance.shadows = [shadow]
+
+fpc.surfaceView.appearance = appearance
+```
+
+* These properties are changed for the top, left and right positioned panel.
+  * `grabberTopPadding` is now `grabberHandlePadding`.
+  * `topGrabberBarHeight` is now `grabberAreaOffset`.
+  * `grabberHandleWidth` and `grabberHandleHeight` are replaced with `grabberHandleSize`.
+
+## `BackdropView`
+
+* The dismissal action of the backdrop is disabled by default.
+  * You can enable it to set `BackdropView.dismissalTapGestureRecognizer.isEnabled` to `true`.
+
+## `FloatingPanelPanGestureRecognizer`
+
+* `delegateProxy` property is added to intercept the gesture recognizer delegate.
+
+```swift
+func layoutPanelForPad() {
+    fpc.behavior = SearchPaneliPadBehavior()
+    fpc.panGestureRecognizer.delegateProxy = self
+}
+
+func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+    return false
+}
+```
+
+## Miscellaneous
+
+* `UISpringTimingParameters(decelerationRate:frequencyResponse:initialVelocity:)` initializer is added.
+* The directory structure and file names in the Xcode project changes.

Examples/Maps/Maps.xcodeproj/project.pbxproj

@@ -8,6 +8,7 @@
 
 /* Begin PBXBuildFile section */
 		543844BD23D2BE2000D5EDE4 /* MapKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 543844BC23D2BE2000D5EDE4 /* MapKit.framework */; };
+		549A5F59244673FE0025F312 /* SearchViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 549A5F58244673FE0025F312 /* SearchViewController.swift */; };
 		549D23D2233C77D5008EF4D7 /* FloatingPanel.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 549D23D1233C77D5008EF4D7 /* FloatingPanel.framework */; };
 		549D23D3233C77D5008EF4D7 /* FloatingPanel.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 549D23D1233C77D5008EF4D7 /* FloatingPanel.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
 		54B5112A216C3D840033A6F3 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54B51129216C3D840033A6F3 /* AppDelegate.swift */; };
@@ -15,6 +16,8 @@
 		54B5112F216C3D840033A6F3 /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 54B5112D216C3D840033A6F3 /* Main.storyboard */; };
 		54B51131216C3D860033A6F3 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 54B51130216C3D860033A6F3 /* Assets.xcassets */; };
 		54B51134216C3D860033A6F3 /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 54B51132216C3D860033A6F3 /* LaunchScreen.storyboard */; };
+		54E26CB624A989090066C720 /* Utils.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54E26CB524A989090066C720 /* Utils.swift */; };
+		54E26CB824A98E310066C720 /* DetailViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54E26CB724A98E310066C720 /* DetailViewController.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXCopyFilesBuildPhase section */
@@ -33,6 +36,7 @@
 
 /* Begin PBXFileReference section */
 		543844BC23D2BE2000D5EDE4 /* MapKit.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = MapKit.framework; path = System/Library/Frameworks/MapKit.framework; sourceTree = SDKROOT; };
+		549A5F58244673FE0025F312 /* SearchViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SearchViewController.swift; sourceTree = "<group>"; };
 		549D23D1233C77D5008EF4D7 /* FloatingPanel.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = FloatingPanel.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		54B51126216C3D840033A6F3 /* Maps.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Maps.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		54B51129216C3D840033A6F3 /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
@@ -41,6 +45,8 @@
 		54B51130216C3D860033A6F3 /* Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Assets.xcassets; sourceTree = "<group>"; };
 		54B51133216C3D860033A6F3 /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/LaunchScreen.storyboard; sourceTree = "<group>"; };
 		54B51135216C3D860033A6F3 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
+		54E26CB524A989090066C720 /* Utils.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Utils.swift; sourceTree = "<group>"; };
+		54E26CB724A98E310066C720 /* DetailViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DetailViewController.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -87,6 +93,9 @@
 			children = (
 				54B51129216C3D840033A6F3 /* AppDelegate.swift */,
 				54B5112B216C3D840033A6F3 /* ViewController.swift */,
+				549A5F58244673FE0025F312 /* SearchViewController.swift */,
+				54E26CB724A98E310066C720 /* DetailViewController.swift */,
+				54E26CB524A989090066C720 /* Utils.swift */,
 				54B5112D216C3D840033A6F3 /* Main.storyboard */,
 				54B51130216C3D860033A6F3 /* Assets.xcassets */,
 				54B51132216C3D860033A6F3 /* LaunchScreen.storyboard */,
@@ -167,8 +176,11 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				549A5F59244673FE0025F312 /* SearchViewController.swift in Sources */,
 				54B5112C216C3D840033A6F3 /* ViewController.swift in Sources */,
+				54E26CB824A98E310066C720 /* DetailViewController.swift in Sources */,
 				54B5112A216C3D840033A6F3 /* AppDelegate.swift in Sources */,
+				54E26CB624A989090066C720 /* Utils.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -317,7 +329,7 @@
 				CODE_SIGN_STYLE = Automatic;
 				DEVELOPMENT_TEAM = "";
 				INFOPLIST_FILE = Maps/Info.plist;
-				IPHONEOS_DEPLOYMENT_TARGET = 10.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 11.0;
 				LD_RUNPATH_SEARCH_PATHS = (
 					"$(inherited)",
 					"@executable_path/Frameworks",
@@ -336,7 +348,7 @@
 				CODE_SIGN_STYLE = Automatic;
 				DEVELOPMENT_TEAM = "";
 				INFOPLIST_FILE = Maps/Info.plist;
-				IPHONEOS_DEPLOYMENT_TARGET = 10.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 11.0;
 				LD_RUNPATH_SEARCH_PATHS = (
 					"$(inherited)",
 					"@executable_path/Frameworks",

Examples/Maps/Maps/AppDelegate.swift

@@ -1,10 +1,4 @@
-//
-//  AppDelegate.swift
-//  Maps
-//
-//  Created by Shin Yamamoto on 2018/10/09.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import UIKit
 

Examples/Maps/Maps/Base.lproj/Main.storyboard

@@ -1,11 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="14313.18" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
-    <device id="retina5_9" orientation="portrait">
-        <adaptation id="fullscreen"/>
-    </device>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="16096" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
+    <device id="retina5_9" orientation="portrait" appearance="light"/>
     <dependencies>
         <deployment identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="14283.14"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="16087"/>
         <capability name="Safe area layout guides" minToolsVersion="9.0"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
@@ -51,18 +49,18 @@
             </objects>
             <point key="canvasLocation" x="136.80000000000001" y="133.00492610837438"/>
         </scene>
-        <!--Search Panel View Controller-->
+        <!--Search View Controller-->
         <scene sceneID="kXy-li-p3C">
             <objects>
-                <viewController storyboardIdentifier="SearchPanel" useStoryboardIdentifierAsRestorationIdentifier="YES" id="0S1-Lk-JgE" customClass="SearchPanelViewController" customModule="Maps" customModuleProvider="target" sceneMemberID="viewController">
+                <viewController storyboardIdentifier="SearchViewController" useStoryboardIdentifierAsRestorationIdentifier="YES" id="0S1-Lk-JgE" customClass="SearchViewController" customModule="Maps" customModuleProvider="target" sceneMemberID="viewController">
                     <view key="view" contentMode="scaleToFill" id="Ncl-E9-yRn">
                         <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <visualEffectView opaque="NO" contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="Ye3-uU-bq3">
-                                <rect key="frame" x="0.0" y="0.0" width="375" height="900"/>
+                                <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
                                 <view key="contentView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" insetsLayoutMarginsFromSafeArea="NO" id="ED1-gT-FBj">
-                                    <rect key="frame" x="0.0" y="0.0" width="375" height="900"/>
+                                    <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <searchBar contentMode="redraw" searchBarStyle="minimal" translatesAutoresizingMaskIntoConstraints="NO" id="Zcj-SE-gb8">
@@ -70,7 +68,7 @@
                                             <textInputTraits key="textInputTraits"/>
                                         </searchBar>
                                         <tableView clipsSubviews="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" showsHorizontalScrollIndicator="NO" showsVerticalScrollIndicator="NO" dataMode="prototypes" style="plain" separatorStyle="default" rowHeight="-1" estimatedRowHeight="-1" sectionHeaderHeight="28" sectionFooterHeight="28" translatesAutoresizingMaskIntoConstraints="NO" id="D7r-re-InH">
-                                            <rect key="frame" x="0.0" y="66" width="375" height="748"/>
+                                            <rect key="frame" x="0.0" y="66" width="375" height="746"/>
                                             <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                                             <view key="tableHeaderView" contentMode="scaleToFill" id="u28-LY-hIh" customClass="SearchHeaderView" customModule="Maps" customModuleProvider="target">
                                                 <rect key="frame" x="0.0" y="0.0" width="375" height="116"/>
@@ -173,7 +171,7 @@
                                                     <rect key="frame" x="0.0" y="144" width="375" height="70"/>
                                                     <autoresizingMask key="autoresizingMask"/>
                                                     <tableViewCellContentView key="contentView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" insetsLayoutMarginsFromSafeArea="NO" tableViewCell="LzC-B9-Adb" id="evr-60-laS">
-                                                        <rect key="frame" x="0.0" y="0.0" width="375" height="69.666666666666671"/>
+                                                        <rect key="frame" x="0.0" y="0.0" width="375" height="70"/>
                                                         <autoresizingMask key="autoresizingMask"/>
                                                         <subviews>
                                                             <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" image="like" translatesAutoresizingMaskIntoConstraints="NO" id="GEk-yE-lLq">
@@ -185,7 +183,7 @@
                                                                 </constraints>
                                                             </imageView>
                                                             <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" distribution="fillEqually" spacing="2" translatesAutoresizingMaskIntoConstraints="NO" id="Gfl-Oy-rsy">
-                                                                <rect key="frame" x="57" y="11.999999999999996" width="303" height="45.666666666666657"/>
+                                                                <rect key="frame" x="57" y="12" width="303" height="46"/>
                                                                 <subviews>
                                                                     <label opaque="NO" userInteractionEnabled="NO" tag="1" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Favorites" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="Spf-8L-Ne6">
                                                                         <rect key="frame" x="0.0" y="0.0" width="303" height="22"/>
@@ -194,7 +192,7 @@
                                                                         <nil key="highlightedColor"/>
                                                                     </label>
                                                                     <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="0 Places" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="gyo-3V-7U8">
-                                                                        <rect key="frame" x="0.0" y="24" width="303" height="21.666666666666671"/>
+                                                                        <rect key="frame" x="0.0" y="24" width="303" height="22"/>
                                                                         <fontDescription key="fontDescription" type="system" pointSize="13"/>
                                                                         <color key="textColor" red="0.57647058819999997" green="0.57647058819999997" blue="0.57647058819999997" alpha="1" colorSpace="calibratedRGB"/>
                                                                         <nil key="highlightedColor"/>
@@ -227,7 +225,7 @@
                                         <constraint firstAttribute="trailing" secondItem="D7r-re-InH" secondAttribute="trailing" id="BES-GA-Btp"/>
                                         <constraint firstItem="D7r-re-InH" firstAttribute="leading" secondItem="ED1-gT-FBj" secondAttribute="leading" id="UTe-YL-17h"/>
                                         <constraint firstItem="Zcj-SE-gb8" firstAttribute="top" secondItem="ED1-gT-FBj" secondAttribute="top" constant="6" id="apU-Pd-PEO"/>
-                                        <constraint firstAttribute="bottom" secondItem="D7r-re-InH" secondAttribute="bottom" constant="86" id="vfS-Lx-TXz"/>
+                                        <constraint firstAttribute="bottom" secondItem="D7r-re-InH" secondAttribute="bottom" id="vfS-Lx-TXz"/>
                                         <constraint firstItem="D7r-re-InH" firstAttribute="top" secondItem="Zcj-SE-gb8" secondAttribute="bottom" constant="4" id="vro-cd-B9c"/>
                                         <constraint firstItem="Zcj-SE-gb8" firstAttribute="leading" secondItem="ED1-gT-FBj" secondAttribute="leading" id="wMb-L2-Z0W"/>
                                     </constraints>
@@ -238,7 +236,7 @@
                         <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <constraints>
                             <constraint firstItem="Ye3-uU-bq3" firstAttribute="leading" secondItem="G74-X7-Za8" secondAttribute="leading" id="Kr2-sU-ZWZ"/>
-                            <constraint firstItem="Ye3-uU-bq3" firstAttribute="bottom" secondItem="Ncl-E9-yRn" secondAttribute="bottom" constant="88" id="aWM-s3-3o4"/>
+                            <constraint firstItem="Ye3-uU-bq3" firstAttribute="bottom" secondItem="Ncl-E9-yRn" secondAttribute="bottom" id="aWM-s3-3o4"/>
                             <constraint firstItem="Ye3-uU-bq3" firstAttribute="trailing" secondItem="G74-X7-Za8" secondAttribute="trailing" id="fEL-8y-Acc"/>
                             <constraint firstItem="Ye3-uU-bq3" firstAttribute="top" secondItem="Ncl-E9-yRn" secondAttribute="top" id="w77-ba-FrJ"/>
                         </constraints>
@@ -254,6 +252,44 @@
             </objects>
             <point key="canvasLocation" x="789.60000000000002" y="133.5832083958021"/>
         </scene>
+        <!--Detail View Controller-->
+        <scene sceneID="5tH-Ya-PzB">
+            <objects>
+                <viewController storyboardIdentifier="DetailViewController" id="Tp2-MF-IFz" customClass="DetailViewController" customModule="Maps" customModuleProvider="target" sceneMemberID="viewController">
+                    <view key="view" contentMode="scaleToFill" id="FmO-AT-4Y7">
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <visualEffectView opaque="NO" contentMode="scaleToFill" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="c3d-2e-0b1">
+                                <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
+                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
+                                <view key="contentView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" insetsLayoutMarginsFromSafeArea="NO" id="9fL-a5-0LS">
+                                    <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
+                                    <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                                    <subviews>
+                                        <tableView clipsSubviews="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" showsHorizontalScrollIndicator="NO" showsVerticalScrollIndicator="NO" dataMode="prototypes" style="plain" separatorStyle="default" rowHeight="-1" estimatedRowHeight="-1" sectionHeaderHeight="28" sectionFooterHeight="28" translatesAutoresizingMaskIntoConstraints="NO" id="kP7-56-wlG">
+                                            <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
+                                            <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
+                                        </tableView>
+                                    </subviews>
+                                    <constraints>
+                                        <constraint firstItem="kP7-56-wlG" firstAttribute="leading" secondItem="9fL-a5-0LS" secondAttribute="leading" id="6gf-GO-cnv"/>
+                                        <constraint firstAttribute="bottom" secondItem="kP7-56-wlG" secondAttribute="bottom" id="WrH-tz-UQF"/>
+                                        <constraint firstItem="kP7-56-wlG" firstAttribute="top" secondItem="9fL-a5-0LS" secondAttribute="top" id="aJk-bz-lVc"/>
+                                        <constraint firstAttribute="trailing" secondItem="kP7-56-wlG" secondAttribute="trailing" id="sE0-9V-Rot"/>
+                                    </constraints>
+                                </view>
+                                <blurEffect style="extraLight"/>
+                            </visualEffectView>
+                        </subviews>
+                        <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
+                        <viewLayoutGuide key="safeArea" id="ctv-Dd-JUc"/>
+                    </view>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="EDp-D2-xcT" userLabel="First Responder" customClass="UIResponder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="1447" y="133"/>
+        </scene>
     </scenes>
     <resources>
         <image name="food" width="60" height="60"/>

Examples/Maps/Maps/DetailViewController.swift

@@ -0,0 +1,7 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+
+class DetailViewController: UIViewController {
+    var item: LocationItem?
+}

Examples/Maps/Maps/SearchViewController.swift

@@ -0,0 +1,181 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+
+// MARK: - UITableViewDelegate
+
+extension ViewController: UITableViewDelegate {
+    func setUpSearchView() {
+        searchVC.loadViewIfNeeded()
+        searchVC.tableView.delegate = self
+        searchVC.searchBar.placeholder = "Search for a place or address"
+        let isPad = (traitCollection.userInterfaceIdiom == .pad)
+        searchVC.items = [
+            .init(mark: "mark", title: "Marked Location" + (isPad ? " (Left panel)" : ""), subtitle: "Golden Gate Bridge, San Francisco"),
+            .init(mark: "mark", title: "Marked Location"  + (isPad ? " (Right panel)" : ""), subtitle: "San Francisco Museum of Modern Art"),
+        ]
+        searchVC.items.append(contentsOf: (0...98).map {
+            .init(mark: "like", title: "Favorites", subtitle: "\($0) Places")
+        })
+    }
+
+    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
+        tableView.deselectRow(at: indexPath, animated: true)
+        // Show a detail panel
+        switch indexPath.row {
+        case 0:
+            detailVC.item = searchVC.items[safe: 0]
+
+            // Show detail vc in the left positioned panel
+            switch traitCollection.userInterfaceIdiom {
+            case .pad:
+                detailFpc.layout = DetailPanelPadLeftLayout()
+                detailFpc.surfaceView.containerMargins = UIEdgeInsets(top: 0.0, left: 16.0, bottom: 0.0, right: 0.0)
+            default:
+                detailFpc.layout = DetailPanelPhoneLayout()
+                detailFpc.surfaceView.containerMargins = .zero
+            }
+            detailFpc.addPanel(toParent: self, animated: true)
+        case 1:
+            detailVC.item = searchVC.items[safe: 1]
+
+            // Show detail vc in the right positioned panel
+            switch traitCollection.userInterfaceIdiom {
+            case .pad:
+                detailFpc.layout = DetailPanelPadRightLayout()
+                detailFpc.surfaceView.containerMargins = UIEdgeInsets(top: 0.0, left: 0.0, bottom: 0.0, right: 16.0)
+            default:
+                detailFpc.layout = DetailPanelPhoneLayout()
+                detailFpc.surfaceView.containerMargins = .zero
+            }
+            detailFpc.addPanel(toParent: self, animated: true)
+        default:
+            break
+        }
+    }
+}
+
+// MARK: - Models
+
+struct LocationItem {
+    let mark: String
+    let title: String
+    let subtitle: String
+
+    init(mark: String, title: String, subtitle: String) {
+        self.mark = mark
+        self.title = title
+        self.subtitle = subtitle
+    }
+}
+
+// MARK: -
+
+class SearchViewController: UIViewController, UITableViewDataSource {
+    @IBOutlet weak var tableView: UITableView!
+    @IBOutlet weak var searchBar: UISearchBar!
+    @IBOutlet weak var visualEffectView: UIVisualEffectView!
+
+    var items: [LocationItem] = []
+
+    // For iOS 10 only
+    private lazy var shadowLayer: CAShapeLayer = CAShapeLayer()
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        tableView.dataSource = self
+        searchBar.setSearchText(fontSize: 15.0)
+
+        hideHeader(animated: false)
+    }
+
+    override func viewDidLayoutSubviews() {
+        super.viewDidLayoutSubviews()
+        if #available(iOS 11, *) {
+        } else {
+            // Exmaple: Add rounding corners on iOS 10
+            visualEffectView.layer.cornerRadius = 9.0
+            visualEffectView.clipsToBounds = true
+
+            // Exmaple: Add shadow manually on iOS 10
+            view.layer.insertSublayer(shadowLayer, at: 0)
+            let rect = visualEffectView.frame
+            let path = UIBezierPath(roundedRect: rect,
+                                    byRoundingCorners: [.topLeft, .topRight],
+                                    cornerRadii: CGSize(width: 9.0, height: 9.0))
+            shadowLayer.frame = visualEffectView.frame
+            shadowLayer.shadowPath = path.cgPath
+            shadowLayer.shadowColor = UIColor.black.cgColor
+            shadowLayer.shadowOffset = CGSize(width: 0.0, height: 1.0)
+            shadowLayer.shadowOpacity = 0.2
+            shadowLayer.shadowRadius = 3.0
+        }
+    }
+
+    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
+        return items.count
+    }
+
+    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
+        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
+        if let cell = cell as? SearchCell, let item = items[safe: indexPath.row] {
+            cell.iconImageView.image = UIImage(named: item.mark)
+            cell.titleLabel.text = item.title
+            cell.subTitleLabel.text = item.subtitle
+        }
+        return cell
+    }
+
+    func showHeader(animated: Bool) {
+        changeHeader(height: 116.0, aniamted: animated)
+    }
+
+    func hideHeader(animated: Bool) {
+        changeHeader(height: 0.0, aniamted: animated)
+    }
+
+    private func changeHeader(height: CGFloat, aniamted: Bool) {
+        guard let headerView = tableView.tableHeaderView, headerView.bounds.height != height else { return }
+        if aniamted == false {
+            updateHeader(height: height)
+            return
+        }
+        tableView.beginUpdates()
+        UIView.animate(withDuration: 0.25) {
+            self.updateHeader(height: height)
+        }
+        tableView.endUpdates()
+    }
+
+    private func updateHeader(height: CGFloat) {
+        guard let headerView = tableView.tableHeaderView else { return }
+        var frame = headerView.frame
+        frame.size.height = height
+        self.tableView.tableHeaderView?.frame = frame
+    }
+}
+
+class SearchCell: UITableViewCell {
+    @IBOutlet weak var iconImageView: UIImageView!
+    @IBOutlet weak var titleLabel: UILabel!
+    @IBOutlet weak var subTitleLabel: UILabel!
+}
+
+class SearchHeaderView: UIView {
+    required init?(coder aDecoder: NSCoder) {
+        super.init(coder: aDecoder)
+        self.clipsToBounds = true
+    }
+}
+
+extension UISearchBar {
+    func setSearchText(fontSize: CGFloat) {
+        if #available(iOS 13, *) {
+            let font = searchTextField.font
+            searchTextField.font = font?.withSize(fontSize)
+        } else {
+            let textField = value(forKey: "_searchField") as! UITextField
+            textField.font = textField.font?.withSize(fontSize)
+        }
+    }
+}

Examples/Maps/Maps/Utils.swift

@@ -0,0 +1,19 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+
+extension Collection {
+    subscript (safe index: Index) -> Element? {
+        return indices.contains(index) ? self[index] : nil
+    }
+}
+
+extension UIViewController {
+    var isLandscape: Bool {
+        if #available(iOS 13.0, *) {
+            return view.window?.windowScene?.interfaceOrientation.isLandscape ?? false
+        } else {
+            return UIApplication.shared.statusBarOrientation.isLandscape
+        }
+    }
+}

Examples/Maps/Maps/ViewController.swift

@@ -1,46 +1,51 @@
-//
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import UIKit
 import MapKit
 import FloatingPanel
 
-class ViewController: UIViewController, MKMapViewDelegate, UISearchBarDelegate, FloatingPanelControllerDelegate {
-    var fpc: FloatingPanelController!
-    var searchVC: SearchPanelViewController!
+class ViewController: UIViewController {
+    typealias PanelDelegate = FloatingPanelControllerDelegate & UIGestureRecognizerDelegate
+
+    // Search Panel
+    lazy var fpc = FloatingPanelController()
+    lazy var fpcDelegate: PanelDelegate =
+        (traitCollection.userInterfaceIdiom == .pad) ? SearchPanelPadDelegate(owner: self) : SearchPanelPhoneDelegate(owner: self)
+    lazy var searchVC =
+        storyboard?.instantiateViewController(withIdentifier: "SearchViewController") as! SearchViewController
+
+    // Detail Panel
+    lazy var detailFpc = FloatingPanelController()
+    lazy var detailFpcDelegate: PanelDelegate =
+        (traitCollection.userInterfaceIdiom == .pad) ? DetailPanelPadDelegate(owner: self) : DetailPanelPhoneDelegate(owner: self)
+    lazy var detailVC =
+        storyboard?.instantiateViewController(withIdentifier: "DetailViewController") as! DetailViewController
 
     @IBOutlet weak var mapView: MKMapView!
 
     override func viewDidLoad() {
         super.viewDidLoad()
-        // Do any additional setup after loading the view, typically from a nib.
-        // Initialize FloatingPanelController
-        fpc = FloatingPanelController()
-        fpc.delegate = self
-
-        // Initialize FloatingPanelController and add the view
-        fpc.surfaceView.backgroundColor = .clear
-        if #available(iOS 11, *) {
-            fpc.surfaceView.cornerRadius = 9.0
-        } else {
-            fpc.surfaceView.cornerRadius = 0.0
-        }
-        fpc.surfaceView.shadowHidden = false
-
-        searchVC = storyboard?.instantiateViewController(withIdentifier: "SearchPanel") as? SearchPanelViewController
-
-        // Set a content view controller
+        fpc.contentMode = .fitToBounds
+        fpc.delegate = fpcDelegate
         fpc.set(contentViewController: searchVC)
         fpc.track(scrollView: searchVC.tableView)
 
+        detailFpc.isRemovalInteractionEnabled = true
+        detailFpc.set(contentViewController: detailVC)
+
+        switch traitCollection.userInterfaceIdiom {
+        case .pad:
+            layoutPanelForPad()
+        default:
+            layoutPanelForPhone()
+        }
+
         setupMapView()
+        setUpSearchView()
     }
 
     override func viewDidAppear(_ animated: Bool) {
         super.viewDidAppear(animated)
-        //  Add FloatingPanel to a view with animation.
-        fpc.addPanel(toParent: self, animated: true)
 
         // Must be here
         searchVC.searchBar.delegate = self
@@ -51,6 +56,327 @@ class ViewController: UIViewController, MKMapViewDelegate, UISearchBarDelegate,
         teardownMapView()
     }
 
+    func layoutPanelForPad() {
+        fpc.behavior = SearchPaneliPadBehavior()
+        fpc.panGestureRecognizer.delegateProxy = fpcDelegate
+
+        // Not use addPanel(toParent:) because of the Auto Layout configuration of fpc.view.
+        view.addSubview(fpc.view)
+        addChild(fpc)
+        fpc.view.frame = view.bounds // Needed for a correct safe area configuration
+        fpc.view.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            fpc.view.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 0.0),
+            fpc.view.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 0.0 ),
+            fpc.view.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: 0.0),
+            fpc.view.rightAnchor.constraint(equalTo: view.safeAreaLayoutGuide.rightAnchor, constant: 0.0),
+        ])
+        fpc.show(animated: false) { [weak self] in
+            guard let self = self else { return }
+            self.didMove(toParent: self)
+        }
+
+        fpc.setAppearanceForPad()
+        detailFpc.setAppearanceForPad()
+    }
+
+    func layoutPanelForPhone() {
+        fpc.track(scrollView: searchVC.tableView) // Only track the tabvle view on iPhone
+        fpc.addPanel(toParent: self, animated: true)
+        fpc.setApearanceForPhone()
+        detailFpc.setApearanceForPhone()
+    }
+}
+
+extension FloatingPanelController {
+    func setApearanceForPhone() {
+        let appearance = SurfaceAppearance()
+        appearance.cornerRadius = 8.0
+        appearance.backgroundColor = .clear
+        surfaceView.appearance = appearance
+    }
+
+    func setAppearanceForPad() {
+        view.clipsToBounds = false
+        let appearance = SurfaceAppearance()
+        appearance.cornerRadius = 8.0
+        let shadow = SurfaceAppearance.Shadow()
+        shadow.color = UIColor.black
+        shadow.offset = CGSize(width: 0, height: 16)
+        shadow.radius = 16
+        shadow.spread = 8
+        appearance.shadows = [shadow]
+        appearance.backgroundColor = .clear
+        surfaceView.appearance = appearance
+    }
+}
+
+// MARK: - UISearchBarDelegate
+
+extension ViewController: UISearchBarDelegate {
+    func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
+        searchBar.resignFirstResponder()
+        searchBar.showsCancelButton  = false
+        searchVC.hideHeader(animated: true)
+        UIView.animate(withDuration: 0.25) {
+            self.fpc.move(to: .half, animated: false)
+        }
+    }
+
+    func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
+        searchBar.showsCancelButton = true
+        searchVC.showHeader(animated: true)
+        searchVC.tableView.alpha = 1.0
+        UIView.animate(withDuration: 0.25) { [weak self] in
+            self?.fpc.move(to: .full, animated: false)
+        }
+    }
+}
+
+// MARK: - iPhone
+
+class SearchPanelPhoneDelegate: NSObject, FloatingPanelControllerDelegate, UIGestureRecognizerDelegate {
+    unowned let owner: ViewController
+
+    init(owner: ViewController) {
+        self.owner = owner
+    }
+
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+        switch newCollection.verticalSizeClass {
+        case .compact:
+            let appearance = vc.surfaceView.appearance
+            appearance.borderWidth = 1.0 / owner.traitCollection.displayScale
+            appearance.borderColor = UIColor.black.withAlphaComponent(0.2)
+            vc.surfaceView.appearance = appearance
+            return SearchPanelLandscapeLayout()
+        default:
+            let appearance = vc.surfaceView.appearance
+            appearance.borderWidth = 0.0
+            appearance.borderColor = nil
+            vc.surfaceView.appearance = appearance
+            return FloatingPanelBottomLayout()
+        }
+    }
+
+    func floatingPanelDidMove(_ vc: FloatingPanelController) {
+        debugPrint("surfaceLocation: ", vc.surfaceLocation)
+        let loc = vc.surfaceLocation
+
+        if vc.isAttracting == false {
+            let minY = vc.surfaceLocation(for: .full).y - 6.0
+            let maxY = vc.surfaceLocation(for: .tip).y + 6.0
+            vc.surfaceLocation = CGPoint(x: loc.x, y: min(max(loc.y, minY), maxY))
+        }
+
+        let tipY = vc.surfaceLocation(for: .tip).y
+        if loc.y > tipY - 44.0 {
+            let progress = max(0.0, min((tipY  - loc.y) / 44.0, 1.0))
+            owner.searchVC.tableView.alpha = progress
+        } else {
+            owner.searchVC.tableView.alpha = 1.0
+        }
+        debugPrint("NearbyState : ",vc.nearbyState)
+    }
+
+    func floatingPanelWillBeginDragging(_ vc: FloatingPanelController) {
+        if vc.state == .full {
+            owner.searchVC.searchBar.showsCancelButton = false
+            owner.searchVC.searchBar.resignFirstResponder()
+        }
+    }
+
+    func floatingPanelWillEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetState: UnsafeMutablePointer<FloatingPanelState>) {
+        if targetState.pointee != .full {
+            owner.searchVC.hideHeader(animated: true)
+        }
+        if targetState.pointee == .tip {
+            vc.contentMode = .static
+        }
+    }
+
+    func floatingPanelDidEndAttracting(_ fpc: FloatingPanelController) {
+        fpc.contentMode = .fitToBounds
+    }
+}
+
+class SearchPanelLandscapeLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition  = .bottom
+    let initialState: FloatingPanelState = .tip
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 69.0, edge: .bottom, referenceGuide: .safeArea),
+        ]
+    }
+    func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
+        if #available(iOS 11.0, *) {
+            return [
+                surfaceView.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 8.0),
+                surfaceView.widthAnchor.constraint(equalToConstant: 291),
+            ]
+        } else {
+            return [
+                surfaceView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 8.0),
+                surfaceView.widthAnchor.constraint(equalToConstant: 291),
+            ]
+        }
+    }
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return 0.0
+    }
+}
+
+class DetailPanelPhoneDelegate: NSObject, FloatingPanelControllerDelegate, UIGestureRecognizerDelegate {
+    unowned let owner: ViewController
+
+    init(owner: ViewController) {
+        self.owner = owner
+    }
+}
+
+class DetailPanelPhoneLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition  = .bottom
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
+        ]
+    }
+    let initialState: FloatingPanelState = .full
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return 0.0
+    }
+}
+
+// MARK: - iPad
+
+class SearchPanelPadDelegate: NSObject, FloatingPanelControllerDelegate, UIGestureRecognizerDelegate {
+    unowned let owner: ViewController
+
+    init(owner: ViewController) {
+        self.owner = owner
+    }
+
+    func floatingPanel(_ fpc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+        if newCollection.horizontalSizeClass == .compact {
+            fpc.surfaceView.containerMargins = .zero
+            return FloatingPanelBottomLayout()
+        }
+        fpc.surfaceView.containerMargins = UIEdgeInsets(top: .leastNonzeroMagnitude, // For top left/right rounding corners
+                                                        left: 16,
+                                                        bottom: 0.0,
+                                                        right: 0.0)
+        return SearchPanelPadLayout()
+    }
+
+    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+        return false
+    }
+
+    func floatingPanelWillBeginDragging(_ vc: FloatingPanelController) {
+        if vc.state == .full {
+            owner.searchVC.searchBar.showsCancelButton = false
+            owner.searchVC.searchBar.resignFirstResponder()
+        }
+    }
+
+    func floatingPanelWillEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetState: UnsafeMutablePointer<FloatingPanelState>) {
+        if targetState.pointee != .full {
+            owner.searchVC.hideHeader(animated: true)
+        }
+    }
+}
+
+class SearchPanelPadLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition  = .top
+    let initialState: FloatingPanelState = .tip
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 80.0, edge: .top, referenceGuide: .superview),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 200.0, edge: .top, referenceGuide: .superview),
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 60.0, edge: .bottom, referenceGuide: .superview),
+        ]
+    }
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return 0.0
+    }
+    func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
+        return [
+            surfaceView.leftAnchor.constraint(equalTo: view.leftAnchor),
+            surfaceView.widthAnchor.constraint(equalToConstant: 375),
+        ]
+    }
+}
+
+class SearchPaneliPadBehavior: FloatingPanelBehavior {
+    var springDecelerationRate: CGFloat {
+        return UIScrollView.DecelerationRate.fast.rawValue - 0.003
+    }
+    var springResponseTime: CGFloat {
+        return 0.3
+    }
+    var momentumProjectionRate: CGFloat {
+        return UIScrollView.DecelerationRate.fast.rawValue
+    }
+    func shouldProjectMomentum(_ fpc: FloatingPanelController, to proposedTargetPosition: FloatingPanelState) -> Bool {
+        return true
+    }
+}
+
+class DetailPanelPadDelegate: NSObject, FloatingPanelControllerDelegate, UIGestureRecognizerDelegate {
+    unowned let owner: ViewController
+
+    init(owner: ViewController) {
+        self.owner = owner
+    }
+
+    func floatingPanel(_ fpc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+        if newCollection.horizontalSizeClass == .compact {
+            fpc.surfaceView.containerMargins = .zero
+            return FloatingPanelBottomLayout()
+        }
+        if let item = owner.detailVC.item, item.title.contains("Right") {
+            fpc.surfaceView.containerMargins = UIEdgeInsets(top: 0.0, left: 0.0, bottom: 0.0, right: .leastNonzeroMagnitude)
+            return DetailPanelPadRightLayout()
+        }
+        fpc.surfaceView.containerMargins = UIEdgeInsets(top: 0.0, left: .leastNonzeroMagnitude, bottom: 0.0, right: 0.0)
+        return DetailPanelPadLeftLayout()
+    }
+
+    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+        return false
+    }
+}
+
+class DetailPanelPadLeftLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition  = .left
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 375, edge: .left, referenceGuide: .superview)
+        ]
+    }
+    let initialState: FloatingPanelState = .full
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return 0.0
+    }
+}
+
+class DetailPanelPadRightLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition  = .right
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 375, edge: .right, referenceGuide: .superview)
+        ]
+    }
+    let initialState: FloatingPanelState = .full
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return 0.0
+    }
+}
+
+// MARK: - MKMapViewDelegate
+
+extension ViewController: MKMapViewDelegate {
     func setupMapView() {
         let center = CLLocationCoordinate2D(latitude: 37.623198015869235,
                                             longitude: -122.43066818432008)
@@ -68,218 +394,4 @@ class ViewController: UIViewController, MKMapViewDelegate, UISearchBarDelegate,
         mapView.delegate = nil
         mapView = nil
     }
-
-    // MARK: UISearchBarDelegate
-
-    func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
-        searchBar.resignFirstResponder()
-        searchBar.showsCancelButton  = false
-        searchVC.hideHeader()
-        fpc.move(to: .half, animated: true)
-    }
-
-    func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
-        searchBar.showsCancelButton = true
-        searchVC.showHeader()
-        searchVC.tableView.alpha = 1.0
-        fpc.move(to: .full, animated: true)
-    }
-
-    // MARK: FloatingPanelControllerDelegate
-    
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
-        switch newCollection.verticalSizeClass {
-        case .compact:
-            fpc.surfaceView.borderWidth = 1.0 / traitCollection.displayScale
-            fpc.surfaceView.borderColor = UIColor.black.withAlphaComponent(0.2)
-            return SearchPanelLandscapeLayout()
-        default:
-            fpc.surfaceView.borderWidth = 0.0
-            fpc.surfaceView.borderColor = nil
-            return nil
-        }
-    }
-
-    func floatingPanelDidMove(_ vc: FloatingPanelController) {
-        let y = vc.surfaceView.frame.origin.y
-        let tipY = vc.originYOfSurface(for: .tip)
-        if y > tipY - 44.0 {
-            let progress = max(0.0, min((tipY  - y) / 44.0, 1.0))
-            self.searchVC.tableView.alpha = progress
-        }
-        debugPrint("NearbyPosition : ",vc.nearbyPosition)
-    }
-
-    func floatingPanelWillBeginDragging(_ vc: FloatingPanelController) {
-        if vc.position == .full {
-            searchVC.searchBar.showsCancelButton = false
-            searchVC.searchBar.resignFirstResponder()
-        }
-    }
-
-    func floatingPanelDidEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetPosition: FloatingPanelPosition) {
-        if targetPosition != .full {
-            searchVC.hideHeader()
-        }
-
-        UIView.animate(withDuration: 0.25,
-                       delay: 0.0,
-                       options: .allowUserInteraction,
-                       animations: {
-                        if targetPosition == .tip {
-                            self.searchVC.tableView.alpha = 0.0
-                        } else {
-                            self.searchVC.tableView.alpha = 1.0
-                        }
-        }, completion: nil)
-    }
-}
-
-class SearchPanelViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
-
-    @IBOutlet weak var tableView: UITableView!
-    @IBOutlet weak var searchBar: UISearchBar!
-    @IBOutlet weak var visualEffectView: UIVisualEffectView!
-
-    // For iOS 10 only
-    private lazy var shadowLayer: CAShapeLayer = CAShapeLayer()
-
-    override func viewDidLoad() {
-        super.viewDidLoad()
-        tableView.dataSource = self
-        tableView.delegate = self
-        searchBar.placeholder = "Search for a place or address"
-        searchBar.setSearchText(fontSize: 15.0)
-
-        hideHeader()
-    }
-
-    override func viewDidLayoutSubviews() {
-        super.viewDidLayoutSubviews()
-        if #available(iOS 11, *) {
-        } else {
-            // Exmaple: Add rounding corners on iOS 10
-            visualEffectView.layer.cornerRadius = 9.0
-            visualEffectView.clipsToBounds = true
-
-            // Exmaple: Add shadow manually on iOS 10
-            view.layer.insertSublayer(shadowLayer, at: 0)
-            let rect = visualEffectView.frame
-            let path = UIBezierPath(roundedRect: rect,
-                                    byRoundingCorners: [.topLeft, .topRight],
-                                    cornerRadii: CGSize(width: 9.0, height: 9.0))
-            shadowLayer.frame = visualEffectView.frame
-            shadowLayer.shadowPath = path.cgPath
-            shadowLayer.shadowColor = UIColor.black.cgColor
-            shadowLayer.shadowOffset = CGSize(width: 0.0, height: 1.0)
-            shadowLayer.shadowOpacity = 0.2
-            shadowLayer.shadowRadius = 3.0
-        }
-    }
-
-    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
-        return 100
-    }
-
-    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
-        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
-        if let cell = cell as? SearchCell {
-            switch indexPath.row {
-            case 0:
-                cell.iconImageView.image = UIImage(named: "mark")
-                cell.titleLabel.text = "Marked Location"
-                cell.subTitleLabel.text = "Golden Gate Bridge, San Francisco"
-            default:
-                cell.iconImageView.image = UIImage(named: "like")
-                cell.titleLabel.text = "Favorites"
-                cell.subTitleLabel.text = "0 Places"
-            }
-        }
-        return cell
-    }
-
-    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
-        tableView.deselectRow(at: indexPath, animated: false)
-    }
-
-    func showHeader() {
-        changeHeader(height: 116.0)
-    }
-
-    func hideHeader() {
-        changeHeader(height: 0.0)
-    }
-
-    func changeHeader(height: CGFloat) {
-        tableView.beginUpdates()
-        if let headerView = tableView.tableHeaderView  {
-            UIView.animate(withDuration: 0.25) {
-                var frame = headerView.frame
-                frame.size.height = height
-                self.tableView.tableHeaderView?.frame = frame
-            }
-        }
-        tableView.endUpdates()
-    }
-}
-
-public class SearchPanelLandscapeLayout: FloatingPanelLayout {
-    public var initialPosition: FloatingPanelPosition {
-        return .tip
-    }
-    
-    public var supportedPositions: Set<FloatingPanelPosition> {
-        return [.full, .tip]
-    }
-
-    public func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return 16.0
-        case .tip: return 69.0
-        default: return nil
-        }
-    }
-
-    public func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
-        if #available(iOS 11.0, *) {
-            return [
-                surfaceView.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 8.0),
-                surfaceView.widthAnchor.constraint(equalToConstant: 291),
-            ]
-        } else {
-            return [
-                surfaceView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 8.0),
-                surfaceView.widthAnchor.constraint(equalToConstant: 291),
-            ]
-        }
-    }
-
-    public func backdropAlphaFor(position: FloatingPanelPosition) -> CGFloat {
-        return 0.0
-    }
-}
-
-class SearchCell: UITableViewCell {
-    @IBOutlet weak var iconImageView: UIImageView!
-    @IBOutlet weak var titleLabel: UILabel!
-    @IBOutlet weak var subTitleLabel: UILabel!
-}
-
-class SearchHeaderView: UIView {
-    required init?(coder aDecoder: NSCoder) {
-        super.init(coder: aDecoder)
-        self.clipsToBounds = true
-    }
-}
-
-extension UISearchBar {
-    func setSearchText(fontSize: CGFloat) {
-        if #available(iOS 13, *) {
-            let font = searchTextField.font
-            searchTextField.font = font?.withSize(fontSize)
-        } else {
-            let textField = value(forKey: "_searchField") as! UITextField
-            textField.font = textField.font?.withSize(fontSize)
-        }
-    }
 }

Examples/Samples/Sources/AppDelegate.swift

@@ -1,7 +1,4 @@
-//
-//  Created by Shin Yamamoto on 2018/09/18.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import UIKit
 

Examples/Samples/Sources/Base.lproj/Main.storyboard

@@ -1,10 +1,11 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="15705" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="RoN-h0-uBD">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="17156" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="RoN-h0-uBD">
     <device id="retina5_9" orientation="portrait" appearance="light"/>
     <dependencies>
         <deployment identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="15706"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="17125"/>
         <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="Stack View standard spacing" minToolsVersion="9.0"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
     <scenes>
@@ -44,7 +45,7 @@
                                             <autoresizingMask key="autoresizingMask"/>
                                             <subviews>
                                                 <label opaque="NO" multipleTouchEnabled="YES" contentMode="left" insetsLayoutMarginsFromSafeArea="NO" text="Title" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" id="M0G-C8-hAO">
-                                                    <rect key="frame" x="15" y="0.0" width="345" height="43.666667938232422"/>
+                                                    <rect key="frame" x="16" y="0.0" width="343" height="43.666667938232422"/>
                                                     <autoresizingMask key="autoresizingMask"/>
                                                     <fontDescription key="fontDescription" type="system" pointSize="17"/>
                                                     <nil key="textColor"/>
@@ -56,6 +57,7 @@
                                 </prototypes>
                             </tableView>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="39L-Nq-qfp"/>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <constraints>
                             <constraint firstItem="7IS-PU-x0P" firstAttribute="top" secondItem="Smh-Bd-AAc" secondAttribute="top" id="6yd-jv-ey3"/>
@@ -63,7 +65,6 @@
                             <constraint firstItem="7IS-PU-x0P" firstAttribute="bottom" secondItem="Smh-Bd-AAc" secondAttribute="bottom" id="fNW-DP-lhV"/>
                             <constraint firstItem="7IS-PU-x0P" firstAttribute="trailing" secondItem="39L-Nq-qfp" secondAttribute="trailing" id="vfY-Rc-FOI"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="39L-Nq-qfp"/>
                     </view>
                     <navigationItem key="navigationItem" title="Samples" id="wCF-su-7up">
                         <barButtonItem key="rightBarButtonItem" title="Settings" id="rbH-U3-XyA">
@@ -88,66 +89,76 @@
                         <rect key="frame" x="0.0" y="0.0" width="375" height="197.33333333333334"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
-                            <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" distribution="fillProportionally" alignment="center" spacing="16" translatesAutoresizingMaskIntoConstraints="NO" id="n93-ZL-fmC">
-                                <rect key="frame" x="32" y="16" width="311" height="181.33333333333334"/>
+                            <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" distribution="fillProportionally" spacing="16" translatesAutoresizingMaskIntoConstraints="NO" id="n93-ZL-fmC">
+                                <rect key="frame" x="32" y="16" width="311" height="149.33333333333334"/>
                                 <subviews>
-                                    <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Version: 1.0" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="WmC-Tq-NDN">
-                                        <rect key="frame" x="118.33333333333334" y="0.0" width="74.333333333333343" height="21"/>
-                                        <fontDescription key="fontDescription" type="system" pointSize="14"/>
-                                        <nil key="textColor"/>
-                                        <nil key="highlightedColor"/>
-                                    </label>
-                                    <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="UINavigationBar" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="Ulg-gS-ah0">
-                                        <rect key="frame" x="90.666666666666686" y="37" width="130" height="25"/>
-                                        <fontDescription key="fontDescription" style="UICTFontTextStyleHeadline"/>
-                                        <nil key="textColor"/>
-                                        <nil key="highlightedColor"/>
-                                    </label>
-                                    <stackView opaque="NO" contentMode="scaleToFill" alignment="center" spacing="126" translatesAutoresizingMaskIntoConstraints="NO" id="uEf-g4-CeU">
-                                        <rect key="frame" x="23.333333333333343" y="78" width="264.66666666666663" height="38"/>
+                                    <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" distribution="fillProportionally" alignment="center" spacing="8" translatesAutoresizingMaskIntoConstraints="NO" id="DCi-Iv-o6d">
+                                        <rect key="frame" x="0.0" y="0.0" width="311" height="52.666666666666664"/>
                                         <subviews>
-                                            <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Large Titles" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="ogl-S5-4tJ">
-                                                <rect key="frame" x="0.0" y="8.9999999999999982" width="89.666666666666671" height="20.333333333333329"/>
-                                                <fontDescription key="fontDescription" type="system" pointSize="17"/>
+                                            <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Version: 1.0" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="WmC-Tq-NDN">
+                                                <rect key="frame" x="118.33333333333334" y="0.0" width="74.333333333333343" height="17.333333333333332"/>
+                                                <fontDescription key="fontDescription" type="system" pointSize="14"/>
+                                                <nil key="textColor"/>
+                                                <nil key="highlightedColor"/>
+                                            </label>
+                                            <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="UINavigationBar" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="Ulg-gS-ah0">
+                                                <rect key="frame" x="78.333333333333329" y="25.333333333333336" width="154.66666666666669" height="27.333333333333336"/>
+                                                <fontDescription key="fontDescription" style="UICTFontTextStyleTitle2"/>
                                                 <nil key="textColor"/>
                                                 <nil key="highlightedColor"/>
                                             </label>
-                                            <switch opaque="NO" contentMode="scaleToFill" horizontalHuggingPriority="750" verticalHuggingPriority="750" contentHorizontalAlignment="center" contentVerticalAlignment="center" translatesAutoresizingMaskIntoConstraints="NO" id="js8-Qv-lUC">
-                                                <rect key="frame" x="215.66666666666666" y="3.6666666666666714" width="50.999999999999972" height="31"/>
-                                                <connections>
-                                                    <action selector="toggleLargeTitle:" destination="C1X-9Z-TyQ" eventType="valueChanged" id="FJS-Ty-mCY"/>
-                                                </connections>
-                                            </switch>
                                         </subviews>
                                     </stackView>
-                                    <stackView opaque="NO" contentMode="scaleToFill" spacing="126" translatesAutoresizingMaskIntoConstraints="NO" id="ZtZ-Dz-4cC">
-                                        <rect key="frame" x="23.333333333333343" y="132" width="264.66666666666663" height="49.333333333333343"/>
+                                    <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" distribution="fillProportionally" spacing="16" translatesAutoresizingMaskIntoConstraints="NO" id="J8j-7w-yCZ">
+                                        <rect key="frame" x="0.0" y="68.666666666666657" width="311" height="80.666666666666657"/>
                                         <subviews>
-                                            <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Translucent" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="Z5i-rm-QgL">
-                                                <rect key="frame" x="0.0" y="0.0" width="89.666666666666671" height="49.333333333333336"/>
-                                                <fontDescription key="fontDescription" type="system" pointSize="17"/>
-                                                <nil key="textColor"/>
-                                                <nil key="highlightedColor"/>
-                                            </label>
-                                            <switch opaque="NO" contentMode="scaleToFill" horizontalHuggingPriority="750" verticalHuggingPriority="750" contentHorizontalAlignment="center" contentVerticalAlignment="center" translatesAutoresizingMaskIntoConstraints="NO" id="s6b-j9-8Kw">
-                                                <rect key="frame" x="215.66666666666666" y="0.0" width="50.999999999999972" height="49.333333333333336"/>
-                                                <connections>
-                                                    <action selector="toggleTranslucent:" destination="C1X-9Z-TyQ" eventType="valueChanged" id="nL4-3L-9hh"/>
-                                                </connections>
-                                            </switch>
+                                            <stackView opaque="NO" contentMode="scaleToFill" alignment="center" spacingType="standard" translatesAutoresizingMaskIntoConstraints="NO" id="uEf-g4-CeU">
+                                                <rect key="frame" x="0.0" y="0.0" width="311" height="32"/>
+                                                <subviews>
+                                                    <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Large Titles" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="ogl-S5-4tJ">
+                                                        <rect key="frame" x="0.0" y="5.9999999999999982" width="254" height="20.333333333333329"/>
+                                                        <fontDescription key="fontDescription" style="UICTFontTextStyleHeadline"/>
+                                                        <nil key="textColor"/>
+                                                        <nil key="highlightedColor"/>
+                                                    </label>
+                                                    <switch opaque="NO" contentMode="scaleToFill" horizontalHuggingPriority="750" verticalHuggingPriority="750" contentHorizontalAlignment="center" contentVerticalAlignment="center" translatesAutoresizingMaskIntoConstraints="NO" id="js8-Qv-lUC">
+                                                        <rect key="frame" x="262" y="0.66666666666665719" width="51" height="31"/>
+                                                        <connections>
+                                                            <action selector="toggleLargeTitle:" destination="C1X-9Z-TyQ" eventType="valueChanged" id="FJS-Ty-mCY"/>
+                                                        </connections>
+                                                    </switch>
+                                                </subviews>
+                                            </stackView>
+                                            <stackView opaque="NO" contentMode="scaleToFill" alignment="center" spacingType="standard" translatesAutoresizingMaskIntoConstraints="NO" id="ZtZ-Dz-4cC">
+                                                <rect key="frame" x="0.0" y="47.999999999999986" width="311" height="32.666666666666671"/>
+                                                <subviews>
+                                                    <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Translucent" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="Z5i-rm-QgL">
+                                                        <rect key="frame" x="0.0" y="6.333333333333341" width="254" height="20.333333333333329"/>
+                                                        <fontDescription key="fontDescription" style="UICTFontTextStyleHeadline"/>
+                                                        <nil key="textColor"/>
+                                                        <nil key="highlightedColor"/>
+                                                    </label>
+                                                    <switch opaque="NO" contentMode="scaleToFill" horizontalHuggingPriority="750" verticalHuggingPriority="750" contentHorizontalAlignment="center" contentVerticalAlignment="center" translatesAutoresizingMaskIntoConstraints="NO" id="s6b-j9-8Kw">
+                                                        <rect key="frame" x="262" y="1" width="51" height="31"/>
+                                                        <connections>
+                                                            <action selector="toggleTranslucent:" destination="C1X-9Z-TyQ" eventType="valueChanged" id="nL4-3L-9hh"/>
+                                                        </connections>
+                                                    </switch>
+                                                </subviews>
+                                            </stackView>
                                         </subviews>
                                     </stackView>
                                 </subviews>
                             </stackView>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="0hr-ty-yWm"/>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <constraints>
-                            <constraint firstItem="0hr-ty-yWm" firstAttribute="bottom" secondItem="n93-ZL-fmC" secondAttribute="bottom" id="2Ey-ou-E1M"/>
+                            <constraint firstAttribute="bottom" secondItem="n93-ZL-fmC" secondAttribute="bottom" constant="32" id="2Ey-ou-E1M"/>
                             <constraint firstAttribute="trailing" secondItem="n93-ZL-fmC" secondAttribute="trailing" constant="32" id="DdZ-eB-F5s"/>
                             <constraint firstItem="n93-ZL-fmC" firstAttribute="leading" secondItem="af9-Zr-Ppc" secondAttribute="leading" constant="32" id="TyK-GP-Ari"/>
                             <constraint firstItem="n93-ZL-fmC" firstAttribute="top" secondItem="af9-Zr-Ppc" secondAttribute="topMargin" constant="16" id="mbC-6H-z9M"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="0hr-ty-yWm"/>
                     </view>
                     <size key="freeformSize" width="375" height="197.33000000000001"/>
                     <connections>
@@ -168,7 +179,7 @@
                         <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
-                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="IvG-yp-yzI">
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="IvG-yp-yzI">
                                 <rect key="frame" x="20" y="44" width="39" height="30"/>
                                 <state key="normal" title="Close"/>
                                 <connections>
@@ -177,13 +188,13 @@
                                 </connections>
                             </button>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="954-Dk-zvc"/>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <constraints>
                             <constraint firstItem="IvG-yp-yzI" firstAttribute="top" secondItem="954-Dk-zvc" secondAttribute="top" id="18k-sV-PgT"/>
                             <constraint firstItem="954-Dk-zvc" firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="IvG-yp-yzI" secondAttribute="trailing" id="mpr-u5-MZu"/>
                             <constraint firstItem="IvG-yp-yzI" firstAttribute="leading" secondItem="954-Dk-zvc" secondAttribute="leading" constant="20" id="pYt-jE-CTF"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="954-Dk-zvc"/>
                     </view>
                     <tabBarItem key="tabBarItem" tag="1" title="Layout 2" id="qb3-RB-B28"/>
                 </viewController>
@@ -199,7 +210,7 @@
                         <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
-                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="NbG-e8-HdI">
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="NbG-e8-HdI">
                                 <rect key="frame" x="20" y="44" width="39" height="30"/>
                                 <state key="normal" title="Close"/>
                                 <connections>
@@ -208,13 +219,13 @@
                                 </connections>
                             </button>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="0ao-SI-QZW"/>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <constraints>
                             <constraint firstItem="0ao-SI-QZW" firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="NbG-e8-HdI" secondAttribute="trailing" id="K9F-6x-KWn"/>
                             <constraint firstItem="NbG-e8-HdI" firstAttribute="top" secondItem="0ao-SI-QZW" secondAttribute="top" id="nsE-so-rTl"/>
                             <constraint firstItem="NbG-e8-HdI" firstAttribute="leading" secondItem="0ao-SI-QZW" secondAttribute="leading" constant="20" id="sF4-Dm-aoY"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="0ao-SI-QZW"/>
                     </view>
                     <tabBarItem key="tabBarItem" tag="2" title="Layout 3" id="RJD-TF-Sdh"/>
                 </viewController>
@@ -230,7 +241,7 @@
                         <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
-                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="eFN-tN-4Ct">
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="eFN-tN-4Ct">
                                 <rect key="frame" x="20" y="44" width="39" height="30"/>
                                 <state key="normal" title="Close"/>
                                 <connections>
@@ -239,13 +250,13 @@
                                 </connections>
                             </button>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="5Ns-4l-Ufg"/>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <constraints>
                             <constraint firstItem="eFN-tN-4Ct" firstAttribute="leading" secondItem="5Ns-4l-Ufg" secondAttribute="leading" constant="20" id="5BT-yZ-EKe"/>
                             <constraint firstItem="5Ns-4l-Ufg" firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="eFN-tN-4Ct" secondAttribute="trailing" id="OzZ-Dz-RNF"/>
                             <constraint firstItem="eFN-tN-4Ct" firstAttribute="top" secondItem="5Ns-4l-Ufg" secondAttribute="top" id="hUV-3a-XkY"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="5Ns-4l-Ufg"/>
                     </view>
                     <tabBarItem key="tabBarItem" title="Layout 1" id="HEV-kf-jxH"/>
                 </viewController>
@@ -262,20 +273,19 @@
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="1000" verticalHuggingPriority="1000" horizontalCompressionResistancePriority="1000" verticalCompressionResistancePriority="1000" text="Change this text" textAlignment="center" lineBreakMode="tailTruncation" numberOfLines="0" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="ge4-RW-Gmz">
-                                <rect key="frame" x="24" y="24" width="327" height="20.333333333333329"/>
+                                <rect key="frame" x="125.66666666666669" y="24" width="124" height="20.333333333333329"/>
                                 <fontDescription key="fontDescription" type="system" pointSize="17"/>
                                 <nil key="textColor"/>
                                 <nil key="highlightedColor"/>
                             </label>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="ouu-g9-OiX"/>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <constraints>
-                            <constraint firstAttribute="trailing" secondItem="ge4-RW-Gmz" secondAttribute="trailing" constant="24" id="V59-MD-Lcg"/>
-                            <constraint firstItem="ge4-RW-Gmz" firstAttribute="leading" secondItem="eLM-xc-d9e" secondAttribute="leading" constant="24" id="hAO-P0-7Kw"/>
                             <constraint firstItem="ge4-RW-Gmz" firstAttribute="top" secondItem="eLM-xc-d9e" secondAttribute="top" constant="24" id="j0s-fd-MYj"/>
                             <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="ge4-RW-Gmz" secondAttribute="bottom" constant="24" id="tEn-PO-nVD"/>
+                            <constraint firstItem="ge4-RW-Gmz" firstAttribute="centerX" secondItem="eLM-xc-d9e" secondAttribute="centerX" id="vh3-l7-uY8"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="ouu-g9-OiX"/>
                     </view>
                     <size key="freeformSize" width="375" height="778"/>
                 </viewController>
@@ -314,7 +324,7 @@
                                 <rect key="frame" x="0.0" y="724" width="375" height="0.0"/>
                                 <color key="backgroundColor" white="0.66666666666666663" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                             </view>
-                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="sbF-Az-7sy">
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="sbF-Az-7sy">
                                 <rect key="frame" x="20" y="0.0" width="39" height="30"/>
                                 <state key="normal" title="Close"/>
                                 <connections>
@@ -324,35 +334,35 @@
                             <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" alignment="top" spacing="44" translatesAutoresizingMaskIntoConstraints="NO" id="9p4-06-y2T">
                                 <rect key="frame" x="134.66666666666666" y="88" width="106" height="326"/>
                                 <subviews>
-                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="i9x-x5-n1q">
+                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="i9x-x5-n1q">
                                         <rect key="frame" x="0.0" y="0.0" width="80" height="30"/>
                                         <state key="normal" title="Move to full"/>
                                         <connections>
                                             <action selector="moveToFullWithSender:" destination="bYI-y3-Rzb" eventType="touchUpInside" id="TDe-3J-gIR"/>
                                         </connections>
                                     </button>
-                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="2u5-cH-RAN">
+                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="2u5-cH-RAN">
                                         <rect key="frame" x="0.0" y="74" width="85" height="30"/>
                                         <state key="normal" title="Move to half"/>
                                         <connections>
                                             <action selector="moveToHalfWithSender:" destination="bYI-y3-Rzb" eventType="touchUpInside" id="12s-o7-Et5"/>
                                         </connections>
                                     </button>
-                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="M4A-iO-RIE">
+                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="M4A-iO-RIE">
                                         <rect key="frame" x="0.0" y="148" width="77" height="30"/>
                                         <state key="normal" title="Move to tip"/>
                                         <connections>
                                             <action selector="moveToTipWithSender:" destination="bYI-y3-Rzb" eventType="touchUpInside" id="BmL-91-9ai"/>
                                         </connections>
                                     </button>
-                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="swr-XM-GzZ">
+                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="swr-XM-GzZ">
                                         <rect key="frame" x="0.0" y="222" width="106" height="30"/>
                                         <state key="normal" title="Move to hidden"/>
                                         <connections>
                                             <action selector="moveToHiddenWithSender:" destination="bYI-y3-Rzb" eventType="touchUpInside" id="jfJ-0f-fdk"/>
                                         </connections>
                                     </button>
-                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="szf-HE-QTk">
+                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="szf-HE-QTk">
                                         <rect key="frame" x="0.0" y="296" width="96" height="30"/>
                                         <state key="normal" title="Update layout"/>
                                         <connections>
@@ -362,6 +372,7 @@
                                 </subviews>
                             </stackView>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="kjr-TP-fcM"/>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <constraints>
                             <constraint firstItem="sbF-Az-7sy" firstAttribute="top" secondItem="kjr-TP-fcM" secondAttribute="top" id="3VR-hj-zeQ"/>
@@ -373,7 +384,6 @@
                             <constraint firstItem="9p4-06-y2T" firstAttribute="centerX" secondItem="kjr-TP-fcM" secondAttribute="centerX" id="l8t-p3-ETf"/>
                             <constraint firstItem="vut-mK-Y4t" firstAttribute="top" secondItem="kjr-TP-fcM" secondAttribute="bottom" id="rMy-JT-t4B"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="kjr-TP-fcM"/>
                     </view>
                     <size key="freeformSize" width="375" height="778"/>
                     <connections>
@@ -466,6 +476,7 @@
                                 </constraints>
                             </scrollView>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="ufS-Rf-F2F"/>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <gestureRecognizers/>
                         <constraints>
@@ -474,7 +485,6 @@
                             <constraint firstAttribute="bottom" secondItem="sBe-tN-uMi" secondAttribute="bottom" id="jzB-47-P7e"/>
                             <constraint firstItem="ufS-Rf-F2F" firstAttribute="trailing" secondItem="sBe-tN-uMi" secondAttribute="trailing" id="nHG-wg-pLP"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="ufS-Rf-F2F"/>
                         <connections>
                             <outletCollection property="gestureRecognizers" destination="tOa-bf-zGz" appends="YES" id="zle-Sz-M3U"/>
                             <outletCollection property="gestureRecognizers" destination="SCk-hG-weZ" appends="YES" id="OcK-FK-Lac"/>
@@ -525,7 +535,7 @@
                                 <rect key="frame" x="0.0" y="44" width="375" height="734"/>
                                 <color key="backgroundColor" red="0.0078431372550000003" green="0.72156862749999995" blue="0.45882352939999999" alpha="1" colorSpace="calibratedRGB"/>
                             </view>
-                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="noi-1a-5bZ" customClass="CloseButton" customModule="Samples" customModuleProvider="target">
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="noi-1a-5bZ" customClass="CloseButton" customModule="Samples" customModuleProvider="target">
                                 <rect key="frame" x="319" y="44" width="44" height="44"/>
                                 <constraints>
                                     <constraint firstAttribute="height" constant="44" id="0jg-5D-A1F"/>
@@ -536,16 +546,16 @@
                                 </connections>
                             </button>
                             <stackView opaque="NO" contentMode="scaleToFill" distribution="fillProportionally" alignment="center" spacing="8" translatesAutoresizingMaskIntoConstraints="NO" id="qux-uG-4o2">
-                                <rect key="frame" x="8" y="52" width="148.33333333333334" height="31"/>
+                                <rect key="frame" x="8" y="52" width="148" height="31"/>
                                 <subviews>
                                     <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="fitToBounds" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="7lq-d3-PKi">
-                                        <rect key="frame" x="0.0" y="5.3333333333333357" width="91.333333333333329" height="20.333333333333332"/>
+                                        <rect key="frame" x="0.0" y="5.3333333333333357" width="91" height="20.333333333333332"/>
                                         <fontDescription key="fontDescription" type="system" pointSize="17"/>
                                         <nil key="textColor"/>
                                         <nil key="highlightedColor"/>
                                     </label>
                                     <switch opaque="NO" contentMode="scaleToFill" horizontalHuggingPriority="750" verticalHuggingPriority="750" contentHorizontalAlignment="center" contentVerticalAlignment="center" on="YES" translatesAutoresizingMaskIntoConstraints="NO" id="0MA-lV-KjS">
-                                        <rect key="frame" x="99.333333333333329" y="0.0" width="50.999999999999986" height="31"/>
+                                        <rect key="frame" x="99" y="0.0" width="51" height="31"/>
                                         <connections>
                                             <action selector="modeChanged:" destination="YC8-ae-15L" eventType="valueChanged" id="IQ8-u2-Rib"/>
                                         </connections>
@@ -553,16 +563,16 @@
                                 </subviews>
                             </stackView>
                             <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" spacing="22" translatesAutoresizingMaskIntoConstraints="NO" id="tP3-oJ-4EB">
-                                <rect key="frame" x="130.66666666666666" y="132" width="114" height="134"/>
+                                <rect key="frame" x="130.66666666666666" y="88" width="114" height="134"/>
                                 <subviews>
-                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="c5r-jU-haj">
+                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="c5r-jU-haj">
                                         <rect key="frame" x="0.0" y="0.0" width="114" height="30"/>
                                         <state key="normal" title="Show"/>
                                         <connections>
                                             <action selector="buttonPressed:" destination="YC8-ae-15L" eventType="touchUpInside" id="Mi1-o6-TWt"/>
                                         </connections>
                                     </button>
-                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="wmd-ab-Nz3">
+                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="wmd-ab-Nz3">
                                         <rect key="frame" x="0.0" y="52" width="114" height="30"/>
                                         <state key="normal" title="Present Modallly"/>
                                         <connections>
@@ -570,7 +580,7 @@
                                             <segue destination="bYI-y3-Rzb" kind="presentation" identifier="PresentModallySegue" id="3yq-HE-Tgn"/>
                                         </connections>
                                     </button>
-                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="01L-lp-oy6">
+                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="01L-lp-oy6">
                                         <rect key="frame" x="0.0" y="104" width="114" height="30"/>
                                         <state key="normal" title="Update Layout"/>
                                         <connections>
@@ -580,6 +590,7 @@
                                 </subviews>
                             </stackView>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="aOK-7l-cA6"/>
                         <color key="backgroundColor" red="1" green="0.83234566450000003" blue="0.47320586440000001" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
                         <gestureRecognizers/>
                         <constraints>
@@ -589,7 +600,7 @@
                             <constraint firstItem="8yw-OC-Ubk" firstAttribute="bottom" secondItem="g7l-kO-y7q" secondAttribute="bottom" id="JOL-wC-w74"/>
                             <constraint firstItem="8yw-OC-Ubk" firstAttribute="leading" secondItem="aOK-7l-cA6" secondAttribute="leading" id="RiJ-Hb-OOZ"/>
                             <constraint firstItem="8yw-OC-Ubk" firstAttribute="trailing" secondItem="aOK-7l-cA6" secondAttribute="trailing" id="Sof-yL-mwK"/>
-                            <constraint firstItem="tP3-oJ-4EB" firstAttribute="top" secondItem="aOK-7l-cA6" secondAttribute="top" constant="88" id="Zhb-Ss-epe"/>
+                            <constraint firstItem="tP3-oJ-4EB" firstAttribute="top" secondItem="g7l-kO-y7q" secondAttribute="top" constant="88" id="Zhb-Ss-epe"/>
                             <constraint firstItem="Kva-Z7-0qY" firstAttribute="trailing" secondItem="aOK-7l-cA6" secondAttribute="trailing" id="kkp-Yo-FQW"/>
                             <constraint firstItem="aOK-7l-cA6" firstAttribute="trailing" secondItem="noi-1a-5bZ" secondAttribute="trailing" constant="12" id="lv9-Nf-HNB"/>
                             <constraint firstItem="qux-uG-4o2" firstAttribute="top" secondItem="aOK-7l-cA6" secondAttribute="top" constant="8" id="naa-cf-ZIc"/>
@@ -598,7 +609,6 @@
                             <constraint firstItem="8yw-OC-Ubk" firstAttribute="top" relation="greaterThanOrEqual" secondItem="tP3-oJ-4EB" secondAttribute="bottom" constant="88" id="vKQ-h9-uKt"/>
                             <constraint firstItem="qux-uG-4o2" firstAttribute="leading" secondItem="g7l-kO-y7q" secondAttribute="leading" constant="8" id="zXb-R9-bMO"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="aOK-7l-cA6"/>
                         <connections>
                             <outletCollection property="gestureRecognizers" destination="6Ca-p8-7uF" appends="YES" id="xOy-f1-NZE"/>
                             <outletCollection property="gestureRecognizers" destination="SPY-Vr-XDT" appends="YES" id="vgS-Am-jhQ"/>
@@ -686,6 +696,7 @@ Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
                                 <textInputTraits key="textInputTraits" autocapitalizationType="sentences"/>
                             </textView>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="5ET-zC-lCb"/>
                         <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <constraints>
                             <constraint firstItem="rN1-HL-YHv" firstAttribute="leading" secondItem="5ET-zC-lCb" secondAttribute="leading" id="7V3-KL-vXd"/>
@@ -693,7 +704,6 @@ Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
                             <constraint firstItem="rN1-HL-YHv" firstAttribute="top" secondItem="9YG-0j-Zzg" secondAttribute="top" constant="17" id="fiO-LL-nSC"/>
                             <constraint firstItem="rN1-HL-YHv" firstAttribute="trailing" secondItem="5ET-zC-lCb" secondAttribute="trailing" id="lfg-EE-euw"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="5ET-zC-lCb"/>
                     </view>
                     <size key="freeformSize" width="375" height="778"/>
                     <connections>
@@ -707,6 +717,11 @@ Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
             <point key="canvasLocation" x="-1" y="734"/>
         </scene>
     </scenes>
+    <designables>
+        <designable name="noi-1a-5bZ">
+            <size key="intrinsicContentSize" width="30" height="30"/>
+        </designable>
+    </designables>
     <inferredMetricsTieBreakers>
         <segue reference="r1P-2i-NDe"/>
     </inferredMetricsTieBreakers>

Examples/Samples/Sources/UIComponents.swift

@@ -1,7 +1,4 @@
-//
-//  Created by Shin Yamamoto on 2018/09/19.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import UIKit
 

Examples/Samples/Sources/UIExtensions.swift

@@ -1,7 +1,4 @@
-//
-//  Created by Shin Yamamoto on 2018/10/08.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import UIKit
 

Examples/Samples/Sources/ViewController.swift

@@ -1,10 +1,4 @@
-//
-//  ViewController.swift
-//  FloatingModalSample
-//
-//  Created by Shin Yamamoto on 2018/09/18.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import UIKit
 import FloatingPanel
@@ -29,6 +23,7 @@ class SampleListViewController: UIViewController {
         case showContentInset
         case showContainerMargins
         case showNavigationController
+        case showBottomEdgeInteraction
 
         var name: String {
             switch self {
@@ -48,6 +43,7 @@ class SampleListViewController: UIViewController {
             case .showContentInset: return "Show with ContentInset"
             case .showContainerMargins: return "Show with ContainerMargins"
             case .showNavigationController: return "Show Navigation Controller"
+            case .showBottomEdgeInteraction: return "Show bottom edge interaction"
             }
         }
 
@@ -69,6 +65,7 @@ class SampleListViewController: UIViewController {
             case .showContentInset: return nil
             case .showContainerMargins: return nil
             case .showNavigationController: return "RootNavigationController"
+            case .showBottomEdgeInteraction: return nil
             }
         }
     }
@@ -133,8 +130,9 @@ class SampleListViewController: UIViewController {
         mainPanelVC.delegate = self
         mainPanelVC.contentInsetAdjustmentBehavior = .always
 
-        mainPanelVC.surfaceView.cornerRadius = 6.0
-        mainPanelVC.surfaceView.shadowHidden = false
+        let appearance = SurfaceAppearance()
+        appearance.cornerRadius = 6.0
+        mainPanelVC.surfaceView.appearance = appearance
 
         mainPanelVC.set(contentViewController: contentVC)
 
@@ -144,18 +142,26 @@ class SampleListViewController: UIViewController {
             let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleSurface(tapGesture:)))
             tapGesture.cancelsTouchesInView = false
             tapGesture.numberOfTapsRequired = 2
+            // Prevents a delay to response a tap in menus of DebugTableViewController.
+            tapGesture.delaysTouchesEnded = false
             mainPanelVC.surfaceView.addGestureRecognizer(tapGesture)
+        case .showNestedScrollView:
+            mainPanelVC.panGestureRecognizer.delegateProxy = self
         case .showPageContentView:
             if let page = (mainPanelVC.contentViewController as? UIPageViewController)?.viewControllers?.first {
                 mainPanelVC.track(scrollView: (page as! DebugTableViewController).tableView)
             }
         case .showRemovablePanel, .showIntrinsicView:
             mainPanelVC.isRemovalInteractionEnabled = true
-
-            let backdropTapGesture = UITapGestureRecognizer(target: self, action: #selector(handleBackdrop(tapGesture:)))
-            mainPanelVC.backdropView.addGestureRecognizer(backdropTapGesture)
+            mainPanelVC.backdropView.dismissalTapGestureRecognizer.isEnabled = true
         case .showNavigationController:
             mainPanelVC.contentInsetAdjustmentBehavior = .never
+        case .showBottomEdgeInteraction: // For debug
+            let contentVC = UIViewController()
+            contentVC.view.backgroundColor = .red
+            mainPanelVC.set(contentViewController: contentVC)
+            mainPanelVC.addPanel(toParent: self, animated: true)
+            return
         default:
             break
         }
@@ -185,16 +191,16 @@ class SampleListViewController: UIViewController {
         //  Add FloatingPanel to self.view
         if let oldMainPanelVC = oldMainPanelVC {
             oldMainPanelVC.removePanelFromParent(animated: true, completion: {
-                self.mainPanelVC.addPanel(toParent: self, belowView: nil, animated: true)
+                self.mainPanelVC.addPanel(toParent: self, animated: true)
             })
         } else {
-            mainPanelVC.addPanel(toParent: self, belowView: nil, animated: true)
+            mainPanelVC.addPanel(toParent: self, animated: true)
         }
     }
 
     @objc
     func handleSurface(tapGesture: UITapGestureRecognizer) {
-        switch mainPanelVC.position {
+        switch mainPanelVC.state {
         case .full:
             mainPanelVC.move(to: .half, animated: true)
         default:
@@ -202,32 +208,18 @@ class SampleListViewController: UIViewController {
         }
     }
 
-    @objc func handleBackdrop(tapGesture: UITapGestureRecognizer) {
-        switch tapGesture.view {
-        case mainPanelVC.backdropView:
-            mainPanelVC.hide(animated: true, completion: nil)
-        case settingsPanelVC.backdropView:
-            settingsPanelVC.removePanelFromParent(animated: true)
-            settingsPanelVC = nil
-        default:
-            break
-        }
-    }
-
     // MARK:- Actions
     @IBAction func showDebugMenu(_ sender: UIBarButtonItem) {
         guard settingsPanelVC == nil else { return }
         // Initialize FloatingPanelController
         settingsPanelVC = FloatingPanelController()
 
-        // Initialize FloatingPanelController and add the view
-        settingsPanelVC.surfaceView.cornerRadius = 6.0
-        settingsPanelVC.surfaceView.shadowHidden = false
+        let appearance = SurfaceAppearance()
+        appearance.cornerRadius = 6.0
+        settingsPanelVC.surfaceView.appearance = appearance
+
         settingsPanelVC.isRemovalInteractionEnabled = true
-
-        let backdropTapGesture = UITapGestureRecognizer(target: self, action: #selector(handleBackdrop(tapGesture:)))
-        settingsPanelVC.backdropView.addGestureRecognizer(backdropTapGesture)
-
+        settingsPanelVC.backdropView.dismissalTapGestureRecognizer.isEnabled = true
         settingsPanelVC.delegate = self
 
         let contentVC = storyboard?.instantiateViewController(withIdentifier: "SettingsViewController")
@@ -236,7 +228,7 @@ class SampleListViewController: UIViewController {
         settingsPanelVC.set(contentViewController: contentVC)
 
         //  Add FloatingPanel to self.view
-        settingsPanelVC.addPanel(toParent: self, belowView: nil, animated: true)
+        settingsPanelVC.addPanel(toParent: self, animated: true)
     }
 }
 
@@ -287,18 +279,18 @@ extension SampleListViewController: UITableViewDelegate {
             detailPanelVC = FloatingPanelController()
             detailPanelVC.delegate = self
 
-            // Initialize FloatingPanelController and add the view
-            detailPanelVC.surfaceView.cornerRadius = 6.0
-            detailPanelVC.surfaceView.shadowHidden = false
+            let appearance = SurfaceAppearance()
+            appearance.cornerRadius = 6.0
+            detailPanelVC.surfaceView.appearance = appearance
 
             // Set a content view controller
             detailPanelVC.set(contentViewController: contentVC)
 
             detailPanelVC.contentMode = .fitToBounds
-            (contentVC as? DetailViewController)?.intrinsicHeightConstraint.priority = .defaultLow
+            (contentVC as? DetailViewController)?.intrinsicHeightConstraint.isActive = false
 
             //  Add FloatingPanel to self.view
-            detailPanelVC.addPanel(toParent: self, belowView: nil, animated: true)
+            detailPanelVC.addPanel(toParent: self, animated: true)
         case .showModal, .showTabBar:
             let modalVC = contentVC
             modalVC.modalPresentationStyle = .fullScreen
@@ -308,6 +300,7 @@ extension SampleListViewController: UITableViewDelegate {
             pages = [UIColor.blue, .red, .green].compactMap({ (color) -> UIViewController in
                 let page = FloatingPanelController(delegate: self)
                 page.view.backgroundColor = color
+                page.panGestureRecognizer.delegateProxy = self
                 page.show()
                 return page
             })
@@ -342,8 +335,10 @@ extension SampleListViewController: UITableViewDelegate {
             fpc.set(contentViewController: contentVC)
             fpc.delegate = self
 
-            fpc.surfaceView.cornerRadius = 38.5
-            fpc.surfaceView.shadowHidden = false
+            let appearance = SurfaceAppearance()
+            appearance.cornerRadius = 38.5
+            fpc.surfaceView.appearance = appearance
+            fpc.backdropView.dismissalTapGestureRecognizer.isEnabled = true
 
             fpc.isRemovalInteractionEnabled = true
 
@@ -359,8 +354,10 @@ extension SampleListViewController: UITableViewDelegate {
             fpc.set(contentViewController: contentVC)
             fpc.delegate = self
 
-            fpc.surfaceView.cornerRadius = 38.5
-            fpc.surfaceView.shadowHidden = false
+            let apprearance = SurfaceAppearance()
+            apprearance.cornerRadius = 38.5
+            apprearance.shadows = []
+            fpc.surfaceView.appearance = apprearance
             fpc.isRemovalInteractionEnabled = true
 
             let mvc = UIViewController()
@@ -373,7 +370,7 @@ extension SampleListViewController: UITableViewDelegate {
 
             let fpc = FloatingPanelController()
             fpc.set(contentViewController: contentViewController)
-            fpc.surfaceView.contentInsets = .init(top: 20, left: 20, bottom: 20, right: 20)
+            fpc.surfaceView.contentPadding = .init(top: 20, left: 20, bottom: 20, right: 20)
 
             fpc.delegate = self
             fpc.isRemovalInteractionEnabled = true
@@ -381,9 +378,13 @@ extension SampleListViewController: UITableViewDelegate {
 
         case .showContainerMargins:
             let fpc = FloatingPanelController()
-            fpc.surfaceView.cornerRadius = 38.5
+
+            let appearance = SurfaceAppearance()
+            appearance.cornerRadius = 38.5
+            fpc.surfaceView.appearance = appearance
+
             fpc.surfaceView.backgroundColor = .red
-            fpc.surfaceView.containerMargins = .init(top: 24.0, left: 8.0, bottom: layoutInsets.bottom, right: 8.0)
+            fpc.surfaceView.containerMargins = .init(top: 24.0, left: 8.0, bottom: max(layoutInsets.bottom, 8.0), right: 8.0)
             #if swift(>=5.1) // Actually Xcode 11 or later
             if #available(iOS 13.0, *) {
                 fpc.surfaceView.layer.cornerCurve = .continuous
@@ -404,20 +405,22 @@ extension SampleListViewController: UITableViewDelegate {
 }
 
 extension SampleListViewController: FloatingPanelControllerDelegate {
-    func floatingPanel(_ vc: FloatingPanelController, contentOffsetForPinning trackedScrollView: UIScrollView) -> CGPoint {
-        if currentMenu == .showNavigationController, #available(iOSApplicationExtension 11.0, *) {
+    func floatingPanel(_ vc: FloatingPanelController, contentOffsetForPinning trackingScrollView: UIScrollView) -> CGPoint {
+        if currentMenu == .showNavigationController, #available(iOS 11.0, *) {
             // 148.0 is the SafeArea's top value for a navigation bar with a large title.
-            return CGPoint(x: 0.0, y: 0.0 - trackedScrollView.contentInset.top - 148.0)
+            return CGPoint(x: 0.0, y: 0.0 - trackingScrollView.contentInset.top - 148.0)
         }
-        return CGPoint(x: 0.0, y: 0.0 - trackedScrollView.contentInset.top)
+        return CGPoint(x: 0.0, y: 0.0 - trackingScrollView.contentInset.top)
     }
 
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
         if vc == settingsPanelVC {
             return IntrinsicPanelLayout()
         }
 
         switch currentMenu {
+        case .showBottomEdgeInteraction:
+            return BottomEdgeInteractionLayout()
         case .showRemovablePanel:
             return newCollection.verticalSizeClass == .compact ? RemovablePanelLandscapeLayout() :  RemovablePanelLayout()
         case .showIntrinsicView:
@@ -428,25 +431,13 @@ extension SampleListViewController: FloatingPanelControllerDelegate {
             }
             fallthrough
         case .showContentInset:
-            return NoInteractionBufferPanelLayout()
+            return FloatingPanelBottomLayout()
         default:
-            return (newCollection.verticalSizeClass == .compact) ? nil : self
+            return (newCollection.verticalSizeClass == .compact) ? FloatingPanelBottomLayout() : self
         }
     }
 
-    func floatingPanel(_ vc: FloatingPanelController, shouldRecognizeSimultaneouslyWith gestureRecognizer: UIGestureRecognizer) -> Bool {
-        switch currentMenu {
-        case .showNestedScrollView:
-            return (vc.contentViewController as? NestedScrollViewController)?.nestedScrollView.gestureRecognizers?.contains(gestureRecognizer) ?? false
-        case .showPageView:
-            // Tips: Need to allow recognizing the pan gesture of UIPageViewController simultaneously.
-            return true
-        default:
-            return false
-        }
-    }
-
-    func floatingPanelDidEndRemove(_ vc: FloatingPanelController) {
+    func floatingPanelDidRemove(_ vc: FloatingPanelController) {
         switch vc {
         case settingsPanelVC:
             settingsPanelVC = nil
@@ -456,23 +447,37 @@ extension SampleListViewController: FloatingPanelControllerDelegate {
     }
 }
 
+extension SampleListViewController: UIGestureRecognizerDelegate {
+    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+        switch currentMenu {
+        case .showNestedScrollView:
+            return true
+        case .showPageView:
+            // Tips: Need to allow recognizing the pan gesture of UIPageViewController simultaneously.
+            return true
+        default:
+            return false
+        }
+    }
+    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+        return false
+    }
+}
+
 /**
  - Attention: `FloatingPanelLayout` must not be applied by the parent view
- controller of a floating panel. But here `SampleListViewController` adopts it
+ controller of a panel. But here `SampleListViewController` adopts it
  purposely to check if the library prints an appropriate warning.
  */
 extension SampleListViewController: FloatingPanelLayout {
-    var initialPosition: FloatingPanelPosition {
-        return .half
-    }
-
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return UIScreen.main.bounds.height == 667.0 ? 18.0 : 16.0
-        case .half: return 262.0
-        case .tip: return 69.0
-        case .hidden: return nil
-        }
+    var position: FloatingPanelPosition { .bottom }
+    var initialState: FloatingPanelState { .half }
+    var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: UIScreen.main.bounds.height == 667.0 ? 18.0 : 16.0, edge: .top, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 262.0, edge: .bottom, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 69.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
     }
 }
 
@@ -501,79 +506,71 @@ extension SampleListViewController: UIPageViewControllerDelegate {
     }
 }
 
-class IntrinsicPanelLayout: FloatingPanelIntrinsicLayout { }
+class BottomEdgeInteractionLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition = .top
+    let initialState: FloatingPanelState = .full
 
-class NoInteractionBufferPanelLayout: FloatingPanelLayout {
-    var initialPosition: FloatingPanelPosition {
-        return .full
-    }
-
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return 0
-        case .half: return 216
-        case .tip: return 60
-        case .hidden: return nil
-        }
-    }
-
-    var topInteractionBuffer: CGFloat {
-        return 0.0
-    }
-
-    var bottomInteractionBuffer: CGFloat {
-        return 0.0
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 88.0, edge: .bottom, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 216.0, edge: .top, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .top, referenceGuide: .safeArea)
+        ]
     }
 }
 
-class RemovablePanelLayout: FloatingPanelIntrinsicLayout {
-    var supportedPositions: Set<FloatingPanelPosition> {
-        return [.full, .half]
+class IntrinsicPanelLayout: FloatingPanelBottomLayout {
+    override var initialState: FloatingPanelState { .full }
+    override var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.0, referenceGuide: .safeArea)
+        ]
     }
-    var initialPosition: FloatingPanelPosition {
-        return .half
-    }
-    var topInteractionBuffer: CGFloat {
-        return 200.0
-    }
-    var bottomInteractionBuffer: CGFloat {
-        return 261.0 - 22.0
+}
+
+class RemovablePanelLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .half
+
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.0, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 130.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
     }
 
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .half: return 130.0
-        default: return nil
-        }
-    }
-    func backdropAlphaFor(position: FloatingPanelPosition) -> CGFloat {
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
         return 0.3
     }
 }
 
-class RemovablePanelLandscapeLayout: FloatingPanelIntrinsicLayout {
-    var supportedPositions: Set<FloatingPanelPosition> {
-        return [.full, .half]
+class RemovablePanelLandscapeLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .full
+
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.0, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 216.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
     }
-    var bottomInteractionBuffer: CGFloat {
-        return 261.0 - 22.0
-    }
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .half: return 261.0
-        default: return nil
-        }
-    }
-    func backdropAlphaFor(position: FloatingPanelPosition) -> CGFloat {
+
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
         return 0.3
     }
 }
 
-class ModalPanelLayout: FloatingPanelIntrinsicLayout {
-    var topInteractionBuffer: CGFloat {
-        return 100.0
+class ModalPanelLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .full
+
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 0.0, referenceGuide: .safeArea),
+        ]
     }
-    func backdropAlphaFor(position: FloatingPanelPosition) -> CGFloat {
+
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
         return 0.3
     }
 }
@@ -689,6 +686,8 @@ class DebugTableViewController: InspectableViewController {
         case animateScroll = "Animate Scroll"
         case changeContentSize = "Change content size"
         case reorder = "Reorder"
+        case moveToFull = "Move to Full"
+        case moveToHalf = "Move to Half"
     }
 
     var reorderButton: UIButton!
@@ -730,6 +729,10 @@ class DebugTableViewController: InspectableViewController {
             case .reorder:
                 button.addTarget(self, action: #selector(reorderItems), for: .touchUpInside)
                 reorderButton = button
+            case .moveToFull:
+                button.addTarget(self, action: #selector(moveToFull), for: .touchUpInside)
+            case .moveToHalf:
+                button.addTarget(self, action: #selector(moveToHalf), for: .touchUpInside)
             }
             buttonStackView.addArrangedSubview(button)
         }
@@ -790,6 +793,14 @@ class DebugTableViewController: InspectableViewController {
         tableView.reloadData()
     }
 
+    @objc func moveToFull() {
+        (self.parent as! FloatingPanelController).move(to: .full, animated: true)
+    }
+
+    @objc func moveToHalf() {
+        (self.parent as! FloatingPanelController).move(to: .half, animated: true)
+    }
+
     @objc func close(sender: UIButton) {
         //  Remove FloatingPanel from a view
         (self.parent as! FloatingPanelController).removePanelFromParent(animated: true, completion: nil)
@@ -887,9 +898,9 @@ class ModalViewController: UIViewController, FloatingPanelControllerDelegate {
         fpc = FloatingPanelController()
         fpc.delegate = self
 
-        // Initialize FloatingPanelController and add the view
-        fpc.surfaceView.cornerRadius = 6.0
-        fpc.surfaceView.shadowHidden = false
+        let appearance = SurfaceAppearance()
+        appearance.cornerRadius = 6.0
+        fpc.surfaceView.appearance = appearance
 
         // Set a content view controller and track the scroll view
         let consoleVC = storyboard?.instantiateViewController(withIdentifier: "ConsoleViewController") as! DebugTextViewController
@@ -899,7 +910,7 @@ class ModalViewController: UIViewController, FloatingPanelControllerDelegate {
         self.consoleVC = consoleVC
 
         //  Add FloatingPanel to self.view
-        fpc.addPanel(toParent: self, belowView: safeAreaView)
+        fpc.addPanel(toParent: self, at: view.subviews.firstIndex(of: safeAreaView) ?? -1)
     }
 
     override func viewDidDisappear(_ animated: Bool) {
@@ -927,27 +938,25 @@ class ModalViewController: UIViewController, FloatingPanelControllerDelegate {
     @IBAction func updateLayout(_ sender: Any) {
         isNewlayout = !isNewlayout
         UIView.animate(withDuration: 0.5) {
-            self.fpc.updateLayout()
+            self.fpc.layout = (self.isNewlayout) ? ModalSecondLayout() : FloatingPanelBottomLayout()
+            self.fpc.invalidateLayout()
         }
     }
 
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
-        return (isNewlayout) ? ModalSecondLayout() : nil
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+        return (isNewlayout) ? ModalSecondLayout() : FloatingPanelBottomLayout()
     }
 }
 
 class ModalSecondLayout: FloatingPanelLayout {
-    var initialPosition: FloatingPanelPosition {
-        return .half
-    }
-
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return 18.0
-        case .half: return 262.0
-        case .tip: return 44.0
-        case .hidden: return nil
-        }
+    var position: FloatingPanelPosition = .bottom
+    var initialState: FloatingPanelState { .half }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 262, edge: .top, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
     }
 }
 
@@ -973,8 +982,10 @@ class TabBarContentViewController: UIViewController {
 
     override func viewDidLoad() {
         fpc.delegate = self
-        fpc.surfaceView.cornerRadius = 6.0
-        fpc.surfaceView.shadowHidden = false
+
+        let appearance = SurfaceAppearance()
+        appearance.cornerRadius = 6.0
+        fpc.surfaceView.appearance = appearance
 
         // Set a content view controller and track the scroll view
         let consoleVC = storyboard?.instantiateViewController(withIdentifier: "ConsoleViewController") as! DebugTextViewController
@@ -987,7 +998,10 @@ class TabBarContentViewController: UIViewController {
         fpc.addPanel(toParent: self)
 
 
-        if tabBarItem.tag == 2 {
+        switch tabBarItem.tag {
+        case 1:
+            fpc.behavior = TwoTabBarPanelBehavior()
+        case 2:
             let switcher = UISwitch()
             fpc.view.addSubview(switcher)
             switcher.translatesAutoresizingMaskIntoConstraints = false
@@ -1014,12 +1028,14 @@ class TabBarContentViewController: UIViewController {
 
             // Turn off the mask instead of content inset change
             consoleVC.textView.clipsToBounds = false
+        default:
+            break
         }
     }
 
     override func viewDidAppear(_ animated: Bool) {
         super.viewDidAppear(animated)
-        fpc.updateLayout()
+        fpc.invalidateLayout()
     }
 
     // MARK: - Action
@@ -1050,7 +1066,7 @@ extension TabBarContentViewController: UITextViewDelegate {
         // Using KVO of `scrollView.contentOffset`). Because it can lead to an
         // infinite loop if a user also resets a content offset as below and,
         // in the situation, a user has to modify the library.
-        if fpc.position != .full, fpc.surfaceView.frame.minY > fpc.originYOfSurface(for: .full) {
+        if fpc.state != .full, fpc.surfaceLocation.y > fpc.surfaceLocation(for: .full).y {
             scrollView.contentOffset = .zero
         }
     }
@@ -1059,7 +1075,7 @@ extension TabBarContentViewController: UITextViewDelegate {
 extension TabBarContentViewController: FloatingPanelControllerDelegate {
     // MARK: - FloatingPanel
 
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
         switch self.tabBarItem.tag {
         case 0:
             return OneTabBarPanelLayout()
@@ -1069,28 +1085,20 @@ extension TabBarContentViewController: FloatingPanelControllerDelegate {
             threeLayout = ThreeTabBarPanelLayout(parent: self)
             return threeLayout
         default:
-            return nil
-        }
-    }
-
-    func floatingPanel(_ vc: FloatingPanelController, behaviorFor newCollection: UITraitCollection) -> FloatingPanelBehavior? {
-        switch self.tabBarItem.tag {
-        case 1:
-            return TwoTabBarPanelBehavior()
-        default:
-            return nil
+            return FloatingPanelBottomLayout()
         }
     }
 
     func floatingPanelDidMove(_ vc: FloatingPanelController) {
         guard self.tabBarItem.tag == 2 else { return }
-
         switch tab3Mode {
         case .changeAutoLayout:
             /* Good solution: Manipulate top constraint */
             assert(consoleVC.textViewTopConstraint != nil)
-            if vc.surfaceView.frame.minY + threeLayout.topPadding < vc.layoutInsets.top {
-                consoleVC.textViewTopConstraint?.constant = vc.layoutInsets.top - vc.surfaceView.frame.minY
+            let safeAreaTop = vc.layoutInsets.top
+            if vc.surfaceLocation.y + threeLayout.topPadding < safeAreaTop {
+                consoleVC.textViewTopConstraint?.constant = min(safeAreaTop - vc.surfaceLocation.y,
+                                                                safeAreaTop)
             } else {
                 consoleVC.textViewTopConstraint?.constant = threeLayout.topPadding
             }
@@ -1116,105 +1124,37 @@ extension TabBarContentViewController: FloatingPanelControllerDelegate {
             }
         }
 
-        if vc.surfaceView.frame.minY > vc.originYOfSurface(for: .half) {
-            let progress = (vc.surfaceView.frame.minY - vc.originYOfSurface(for: .half)) / (vc.originYOfSurface(for: .tip) - vc.originYOfSurface(for: .half))
+        if vc.surfaceLocation.y > vc.surfaceLocation(for: .half).y {
+            let progress = (vc.surfaceLocation.y - vc.surfaceLocation(for: .half).y)
+                / (vc.surfaceLocation(for: .tip).y - vc.surfaceLocation(for: .half).y)
             threeLayout.leftConstraint.constant = max(min(progress, 1.0), 0.0) * threeLayout.sideMargin
             threeLayout.rightConstraint.constant = -max(min(progress, 1.0), 0.0) * threeLayout.sideMargin
         } else {
             threeLayout.leftConstraint.constant = 0.0
             threeLayout.rightConstraint.constant = 0.0
         }
-
-        vc.view.layoutIfNeeded() // MUST
-    }
-
-    func floatingPanelDidChangePosition(_ vc: FloatingPanelController) {
-        guard self.tabBarItem.tag == 2 else { return }
-
-        switch tab3Mode {
-        case .changeAutoLayout:
-            /* Good Solution: Manipulate top constraint */
-            assert(consoleVC.textViewTopConstraint != nil)
-            consoleVC.textViewTopConstraint?.constant = (vc.position == .full) ? vc.layoutInsets.top : 17.0
-
-        case .changeOffset:
-            /* Bad Solution: Manipulate scroll content inset */
-            guard let scrollView = consoleVC.textView else { return }
-            var insets = vc.adjustedContentInsets
-            insets.top = (vc.position == .full) ? vc.layoutInsets.top : 0.0
-            scrollView.contentInset = insets
-            if scrollView.contentOffset.y - scrollView.contentInset.top < 0.0  {
-                scrollView.contentOffset = CGPoint(x: 0.0,
-                                                   y: 0.0 - scrollView.contentInset.top)
-            }
-        }
-
-        if vc.position == .tip {
-            threeLayout.leftConstraint.constant = threeLayout.sideMargin
-            threeLayout.rightConstraint.constant = -threeLayout.sideMargin
-        } else {
-            threeLayout.leftConstraint.constant = 0.0
-            threeLayout.rightConstraint.constant = 0.0
-        }
-        // Can call it, but it's not necessary because it will be also called
-        // by FloatingPanelController after the delegate method
-        vc.view.layoutIfNeeded()
-    }
-}
-
-extension FloatingPanelLayout {
-    func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
-        if #available(iOS 11.0, *) {
-            return [
-                surfaceView.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 0.0),
-                surfaceView.rightAnchor.constraint(equalTo: view.safeAreaLayoutGuide.rightAnchor, constant: 0.0),
-            ]
-        } else {
-            return [
-                surfaceView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 0.0),
-                surfaceView.rightAnchor.constraint(equalTo: view.rightAnchor, constant: 0.0),
-            ]
-        }
     }
 }
 
 class OneTabBarPanelLayout: FloatingPanelLayout {
-    var initialPosition: FloatingPanelPosition {
-        return .tip
-    }
-    var supportedPositions: Set<FloatingPanelPosition> {
-        return [.full, .tip]
-    }
-
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return 16.0
-        case .tip: return 22.0
-        default: return nil
-        }
+    var initialState: FloatingPanelState { .tip }
+    var position: FloatingPanelPosition { .bottom }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 22.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
     }
 }
 
 class TwoTabBarPanelLayout: FloatingPanelLayout {
-    var initialPosition: FloatingPanelPosition {
-        return .half
-    }
-    var supportedPositions: Set<FloatingPanelPosition> {
-        return [.full, .half]
-    }
-    var topInteractionBuffer: CGFloat {
-        return 100.0
-    }
-    var bottomInteractionBuffer: CGFloat {
-        return 261.0 - 22.0
-    }
-
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return 100.0
-        case .half: return 261.0
-        default: return nil
-        }
+    var initialState: FloatingPanelState { .half }
+    var position: FloatingPanelPosition { .bottom }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 100.0, edge: .top, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 261.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
     }
 }
 
@@ -1225,7 +1165,7 @@ class TwoTabBarPanelBehavior: FloatingPanelBehavior {
 }
 
 
-class ThreeTabBarPanelLayout: FloatingPanelFullScreenLayout {
+class ThreeTabBarPanelLayout: FloatingPanelLayout {
     weak var parentVC: UIViewController!
 
     var leftConstraint: NSLayoutConstraint!
@@ -1238,25 +1178,20 @@ class ThreeTabBarPanelLayout: FloatingPanelFullScreenLayout {
         parentVC = parent
     }
 
-    var bottomInteractionBuffer: CGFloat = 44.0
+    var initialState: FloatingPanelState { .half }
+    var position: FloatingPanelPosition { .bottom }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .top, referenceGuide: .superview),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 261.0 + parentVC.layoutInsets.bottom, edge: .bottom, referenceGuide: .superview),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 88.0 + parentVC.layoutInsets.bottom, edge: .bottom, referenceGuide: .superview),
+        ]
+    }
 
-    var initialPosition: FloatingPanelPosition {
-        return .half
-    }
-    var supportedPositions: Set<FloatingPanelPosition> {
-        return [.full, .half, .tip]
-    }
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return 0.0
-        case .half: return 261.0 + parentVC.layoutInsets.bottom
-        case .tip: return 88.0 + parentVC.layoutInsets.bottom
-        default: return nil
-        }
-    }
-    func backdropAlphaFor(position: FloatingPanelPosition) -> CGFloat {
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
         return 0.3
     }
+
     func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
         if #available(iOS 11.0, *) {
             leftConstraint = surfaceView.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 0.0)
@@ -1345,7 +1280,7 @@ final class MultiPanelController: FloatingPanelController, FloatingPanelControll
 
     override func viewDidLoad() {
         super.viewDidLoad()
-        delegate = self
+        layout = FirstViewLayout()
         isRemovalInteractionEnabled = true
 
         let vc = FirstPanelContentViewController()
@@ -1354,28 +1289,12 @@ final class MultiPanelController: FloatingPanelController, FloatingPanelControll
     }
 
     private final class FirstViewLayout: FloatingPanelLayout {
-        let initialPosition: FloatingPanelPosition = .full
-        let supportedPositions: Set<FloatingPanelPosition> = [.full, .half]
-        func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-            switch position {
-            case .full: return 40.0
-            case .half: return 200.0
-            default: return nil
-            }
+        let position: FloatingPanelPosition = .bottom
+        let initialState: FloatingPanelState = .full
+        var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+            return [
+                .full: FloatingPanelLayoutAnchor(absoluteInset: 40.0, edge: .top, referenceGuide: .superview)
+            ]
         }
     }
-
-    private final class FirstViewBehavior: FloatingPanelBehavior {
-        func shouldProjectMomentum(_ fpc: FloatingPanelController, for proposedTargetPosition: FloatingPanelPosition) -> Bool {
-            return true
-        }
-    }
-
-    func floatingPanel(_ vc: FloatingPanelController, behaviorFor newCollection: UITraitCollection) -> FloatingPanelBehavior? {
-        return FirstViewBehavior()
-    }
-
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
-        return FirstViewLayout()
-    }
 }

Examples/Samples/Tests/SampleTests.swift

@@ -1,10 +1,4 @@
-//
-//  FloatingModalSampleTests.swift
-//  FloatingModalSampleTests
-//
-//  Created by Shin Yamamoto on 2018/09/18.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import XCTest
 @testable import FloatingPanelSample

Examples/Samples/UITests/SampleUITests.swift

@@ -1,7 +1,4 @@
-//
-//  Created by Shin Yamamoto on 2018/09/18.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import XCTest
 

Examples/SamplesObjC/SamplesObjC.xcodeproj/project.pbxproj

@@ -0,0 +1,375 @@
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+				545BA70021BA3214007F7846 /* SamplesObjC */,
+			);
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+/* End PBXProject section */
+
+/* Begin PBXResourcesBuildPhase section */
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+			files = (
+				545BA71121BA3217007F7846 /* LaunchScreen.storyboard in Resources */,
+				545BA70E21BA3217007F7846 /* Assets.xcassets in Resources */,
+				545BA70C21BA3214007F7846 /* Main.storyboard in Resources */,
+			);
+			runOnlyForDeploymentPostprocessing = 0;
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+/* End PBXResourcesBuildPhase section */
+
+/* Begin PBXSourcesBuildPhase section */
+		545BA6FD21BA3214007F7846 /* Sources */ = {
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+			buildActionMask = 2147483647;
+			files = (
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+				545BA71421BA3217007F7846 /* main.m in Sources */,
+				545BA70621BA3214007F7846 /* AppDelegate.m in Sources */,
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+			runOnlyForDeploymentPostprocessing = 0;
+		};
+/* End PBXSourcesBuildPhase section */
+
+/* Begin PBXVariantGroup section */
+		545BA70A21BA3214007F7846 /* Main.storyboard */ = {
+			isa = PBXVariantGroup;
+			children = (
+				545BA70B21BA3214007F7846 /* Base */,
+			);
+			name = Main.storyboard;
+			sourceTree = "<group>";
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+		545BA70F21BA3217007F7846 /* LaunchScreen.storyboard */ = {
+			isa = PBXVariantGroup;
+			children = (
+				545BA71021BA3217007F7846 /* Base */,
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+			name = LaunchScreen.storyboard;
+			sourceTree = "<group>";
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+/* End PBXVariantGroup section */
+
+/* Begin XCBuildConfiguration section */
+		545BA71521BA3217007F7846 /* Debug */ = {
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+				CLANG_ANALYZER_NONNULL = YES;
+				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
+				CLANG_CXX_LANGUAGE_STANDARD = "gnu++14";
+				CLANG_CXX_LIBRARY = "libc++";
+				CLANG_ENABLE_MODULES = YES;
+				CLANG_ENABLE_OBJC_ARC = YES;
+				CLANG_ENABLE_OBJC_WEAK = YES;
+				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
+				CLANG_WARN_BOOL_CONVERSION = YES;
+				CLANG_WARN_COMMA = YES;
+				CLANG_WARN_CONSTANT_CONVERSION = YES;
+				CLANG_WARN_DEPRECATED_OBJC_IMPLEMENTATIONS = YES;
+				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
+				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
+				CLANG_WARN_EMPTY_BODY = YES;
+				CLANG_WARN_ENUM_CONVERSION = YES;
+				CLANG_WARN_INFINITE_RECURSION = YES;
+				CLANG_WARN_INT_CONVERSION = YES;
+				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
+				CLANG_WARN_OBJC_IMPLICIT_RETAIN_SELF = YES;
+				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
+				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
+				CLANG_WARN_STRICT_PROTOTYPES = YES;
+				CLANG_WARN_SUSPICIOUS_MOVE = YES;
+				CLANG_WARN_UNGUARDED_AVAILABILITY = YES_AGGRESSIVE;
+				CLANG_WARN_UNREACHABLE_CODE = YES;
+				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
+				CODE_SIGN_IDENTITY = "iPhone Developer";
+				COPY_PHASE_STRIP = NO;
+				DEBUG_INFORMATION_FORMAT = dwarf;
+				ENABLE_STRICT_OBJC_MSGSEND = YES;
+				ENABLE_TESTABILITY = YES;
+				GCC_C_LANGUAGE_STANDARD = gnu11;
+				GCC_DYNAMIC_NO_PIC = NO;
+				GCC_NO_COMMON_BLOCKS = YES;
+				GCC_OPTIMIZATION_LEVEL = 0;
+				GCC_PREPROCESSOR_DEFINITIONS = (
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+					"$(inherited)",
+				);
+				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
+				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
+				GCC_WARN_UNDECLARED_SELECTOR = YES;
+				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
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+				MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
+				MTL_FAST_MATH = YES;
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+			};
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+		};
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+			buildSettings = {
+				ALWAYS_SEARCH_USER_PATHS = NO;
+				CLANG_ANALYZER_NONNULL = YES;
+				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
+				CLANG_CXX_LANGUAGE_STANDARD = "gnu++14";
+				CLANG_CXX_LIBRARY = "libc++";
+				CLANG_ENABLE_MODULES = YES;
+				CLANG_ENABLE_OBJC_ARC = YES;
+				CLANG_ENABLE_OBJC_WEAK = YES;
+				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
+				CLANG_WARN_BOOL_CONVERSION = YES;
+				CLANG_WARN_COMMA = YES;
+				CLANG_WARN_CONSTANT_CONVERSION = YES;
+				CLANG_WARN_DEPRECATED_OBJC_IMPLEMENTATIONS = YES;
+				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
+				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
+				CLANG_WARN_EMPTY_BODY = YES;
+				CLANG_WARN_ENUM_CONVERSION = YES;
+				CLANG_WARN_INFINITE_RECURSION = YES;
+				CLANG_WARN_INT_CONVERSION = YES;
+				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
+				CLANG_WARN_OBJC_IMPLICIT_RETAIN_SELF = YES;
+				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
+				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
+				CLANG_WARN_STRICT_PROTOTYPES = YES;
+				CLANG_WARN_SUSPICIOUS_MOVE = YES;
+				CLANG_WARN_UNGUARDED_AVAILABILITY = YES_AGGRESSIVE;
+				CLANG_WARN_UNREACHABLE_CODE = YES;
+				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
+				CODE_SIGN_IDENTITY = "iPhone Developer";
+				COPY_PHASE_STRIP = NO;
+				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
+				ENABLE_NS_ASSERTIONS = NO;
+				ENABLE_STRICT_OBJC_MSGSEND = YES;
+				GCC_C_LANGUAGE_STANDARD = gnu11;
+				GCC_NO_COMMON_BLOCKS = YES;
+				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
+				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
+				GCC_WARN_UNDECLARED_SELECTOR = YES;
+				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
+				GCC_WARN_UNUSED_FUNCTION = YES;
+				GCC_WARN_UNUSED_VARIABLE = YES;
+				IPHONEOS_DEPLOYMENT_TARGET = 12.1;
+				MTL_ENABLE_DEBUG_INFO = NO;
+				MTL_FAST_MATH = YES;
+				SDKROOT = iphoneos;
+				SWIFT_COMPILATION_MODE = wholemodule;
+				VALIDATE_PRODUCT = YES;
+			};
+			name = Release;
+		};
+		545BA71821BA3217007F7846 /* Debug */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
+				CLANG_ENABLE_MODULES = YES;
+				CODE_SIGN_STYLE = Automatic;
+				DEFINES_MODULE = NO;
+				DEVELOPMENT_TEAM = J3D7L9FHSS;
+				INFOPLIST_FILE = SamplesObjC/Info.plist;
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+				);
+				PRODUCT_BUNDLE_IDENTIFIER = com.scenee.SamplesObjC;
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_OBJC_BRIDGING_HEADER = "SamplesObjC/SamplesObjC-Bridging-Header.h";
+				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_VERSION = 4.2;
+				TARGETED_DEVICE_FAMILY = "1,2";
+			};
+			name = Debug;
+		};
+		545BA71921BA3217007F7846 /* Release */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
+				CLANG_ENABLE_MODULES = YES;
+				CODE_SIGN_STYLE = Automatic;
+				DEFINES_MODULE = NO;
+				DEVELOPMENT_TEAM = J3D7L9FHSS;
+				INFOPLIST_FILE = SamplesObjC/Info.plist;
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+				);
+				PRODUCT_BUNDLE_IDENTIFIER = com.scenee.SamplesObjC;
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_OBJC_BRIDGING_HEADER = "SamplesObjC/SamplesObjC-Bridging-Header.h";
+				SWIFT_VERSION = 4.2;
+				TARGETED_DEVICE_FAMILY = "1,2";
+			};
+			name = Release;
+		};
+/* End XCBuildConfiguration section */
+
+/* Begin XCConfigurationList section */
+		545BA6FC21BA3214007F7846 /* Build configuration list for PBXProject "SamplesObjC" */ = {
+			isa = XCConfigurationList;
+			buildConfigurations = (
+				545BA71521BA3217007F7846 /* Debug */,
+				545BA71621BA3217007F7846 /* Release */,
+			);
+			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
+		};
+		545BA71721BA3217007F7846 /* Build configuration list for PBXNativeTarget "SamplesObjC" */ = {
+			isa = XCConfigurationList;
+			buildConfigurations = (
+				545BA71821BA3217007F7846 /* Debug */,
+				545BA71921BA3217007F7846 /* Release */,
+			);
+			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
+		};
+/* End XCConfigurationList section */
+	};
+	rootObject = 545BA6F921BA3214007F7846 /* Project object */;
+}

Examples/SamplesObjC/SamplesObjC.xcodeproj/project.xcworkspace/contents.xcworkspacedata

@@ -2,6 +2,6 @@
 <Workspace
    version = "1.0">
    <FileRef
-      location = "self:FloatingModalController.xcodeproj">
+      location = "self:SamplesObjC.xcodeproj">
    </FileRef>
 </Workspace>

Examples/SamplesObjC/SamplesObjC.xcodeproj/xcshareddata/xcschemes/SamplesObjC.xcscheme

@@ -0,0 +1,87 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "1110"
+   version = "1.3">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "545BA70021BA3214007F7846"
+               BuildableName = "SamplesObjC.app"
+               BlueprintName = "SamplesObjC"
+               ReferencedContainer = "container:SamplesObjC.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES">
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "545BA70021BA3214007F7846"
+            BuildableName = "SamplesObjC.app"
+            BlueprintName = "SamplesObjC"
+            ReferencedContainer = "container:SamplesObjC.xcodeproj">
+         </BuildableReference>
+      </MacroExpansion>
+      <Testables>
+      </Testables>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "545BA70021BA3214007F7846"
+            BuildableName = "SamplesObjC.app"
+            BlueprintName = "SamplesObjC"
+            ReferencedContainer = "container:SamplesObjC.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "545BA70021BA3214007F7846"
+            BuildableName = "SamplesObjC.app"
+            BlueprintName = "SamplesObjC"
+            ReferencedContainer = "container:SamplesObjC.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

Examples/SamplesObjC/SamplesObjC/AppDelegate.h

@@ -0,0 +1,9 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+#import <UIKit/UIKit.h>
+
+@interface AppDelegate : UIResponder <UIApplicationDelegate>
+
+@property (strong, nonatomic) UIWindow* window;
+
+@end

Examples/SamplesObjC/SamplesObjC/AppDelegate.m

@@ -0,0 +1,9 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+#import "AppDelegate.h"
+
+@interface AppDelegate ()
+@end
+
+@implementation AppDelegate
+@end

Examples/SamplesObjC/SamplesObjC/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -0,0 +1,98 @@
+{
+  "images" : [
+    {
+      "idiom" : "iphone",
+      "size" : "20x20",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "20x20",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "29x29",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "29x29",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "40x40",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "40x40",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "60x60",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "60x60",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "20x20",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "20x20",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "29x29",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "29x29",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "40x40",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "40x40",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "76x76",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "76x76",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "83.5x83.5",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ios-marketing",
+      "size" : "1024x1024",
+      "scale" : "1x"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

Examples/SamplesObjC/SamplesObjC/Assets.xcassets/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

Examples/SamplesObjC/SamplesObjC/Base.lproj/LaunchScreen.storyboard

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="13122.16" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" launchScreen="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="01J-lp-oVM">
+    <dependencies>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="13104.12"/>
+        <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
+    </dependencies>
+    <scenes>
+        <!--View Controller-->
+        <scene sceneID="EHf-IW-A2E">
+            <objects>
+                <viewController id="01J-lp-oVM" sceneMemberID="viewController">
+                    <view key="view" contentMode="scaleToFill" id="Ze5-6b-2t3">
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        <viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/>
+                    </view>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="iYj-Kq-Ea1" userLabel="First Responder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="53" y="375"/>
+        </scene>
+    </scenes>
+</document>

Examples/SamplesObjC/SamplesObjC/Base.lproj/Main.storyboard

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="13122.16" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
+    <dependencies>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="13104.12"/>
+        <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
+    </dependencies>
+    <scenes>
+        <!--View Controller-->
+        <scene sceneID="tne-QT-ifu">
+            <objects>
+                <viewController id="BYZ-38-t0r" customClass="ViewController" customModuleProvider="" sceneMemberID="viewController">
+                    <view key="view" contentMode="scaleToFill" id="8bC-Xf-vdC">
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+                        <viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/>
+                    </view>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>
+            </objects>
+        </scene>
+    </scenes>
+</document>

Examples/SamplesObjC/SamplesObjC/Info.plist

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>$(DEVELOPMENT_LANGUAGE)</string>
+	<key>CFBundleExecutable</key>
+	<string>$(EXECUTABLE_NAME)</string>
+	<key>CFBundleIdentifier</key>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>$(PRODUCT_NAME)</string>
+	<key>CFBundlePackageType</key>
+	<string>APPL</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0</string>
+	<key>CFBundleVersion</key>
+	<string>1</string>
+	<key>LSRequiresIPhoneOS</key>
+	<true/>
+	<key>UILaunchStoryboardName</key>
+	<string>LaunchScreen</string>
+	<key>UIMainStoryboardFile</key>
+	<string>Main</string>
+	<key>UIRequiredDeviceCapabilities</key>
+	<array>
+		<string>armv7</string>
+	</array>
+	<key>UISupportedInterfaceOrientations</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+	<key>UISupportedInterfaceOrientations~ipad</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationPortraitUpsideDown</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+</dict>
+</plist>

Examples/SamplesObjC/SamplesObjC/SamplesObjC-Bridging-Header.h

@@ -0,0 +1,3 @@
+//
+//  Use this file to import your target's public headers that you would like to expose to Swift.
+//

Examples/SamplesObjC/SamplesObjC/ViewController.h

@@ -0,0 +1,13 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+#import <UIKit/UIKit.h>
+@import FloatingPanel;
+
+@interface ViewController : UIViewController
+@end
+
+@interface MyFloatingPanelLayout : NSObject <FloatingPanelLayout>
+@end
+
+@interface MyFloatingPanelBehavior : NSObject <FloatingPanelBehavior>
+@end

Examples/SamplesObjC/SamplesObjC/ViewController.m

@@ -0,0 +1,78 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+#import "ViewController.h"
+@import FloatingPanel;
+
+@interface ViewController()<FloatingPanelControllerDelegate>
+@end
+
+@implementation ViewController
+
+- (void)viewDidLoad {
+    [super viewDidLoad];
+
+    FloatingPanelController *fpc = [[FloatingPanelController alloc] init];
+    [fpc setContentViewController:nil];
+    [fpc trackScrollView:nil];
+    [fpc setDelegate:self];
+
+    [fpc setLayout: [MyFloatingPanelLayout new]];
+    [fpc setBehavior:[MyFloatingPanelBehavior new]];
+    [fpc setRemovalInteractionEnabled:NO];
+
+    [fpc addPanelToParent:self at:self.view.subviews.count  animated:NO];
+    [fpc moveToState:FloatingPanelState.Tip animated:true completion:nil];
+
+    [self updateAppearance: fpc];
+}
+
+- (id<FloatingPanelLayout>)floatingPanel:(FloatingPanelController *)vc layoutFor:(UITraitCollection *)newCollection {
+    FloatingPanelBottomLayout *layout = [FloatingPanelBottomLayout new];
+    return layout;
+}
+
+- (void)updateAppearance: (FloatingPanelController*)fpc
+{
+    FloatingPanelSurfaceAppearance *appearance = [[FloatingPanelSurfaceAppearance alloc] init];
+    appearance.backgroundColor = [UIColor clearColor];
+    appearance.cornerRadius = 23.0;
+    if (@available(iOS 13.0, *)) {
+        fpc.surfaceView.containerView.layer.cornerCurve = kCACornerCurveContinuous;
+    }
+    FloatingPanelSurfaceAppearanceShadow *shadow = [[FloatingPanelSurfaceAppearanceShadow alloc] init];
+    shadow.color = [UIColor redColor];
+    shadow.radius = 10.0;
+    shadow.spread = 10.0;
+    FloatingPanelSurfaceAppearanceShadow *shadow2 = [[FloatingPanelSurfaceAppearanceShadow alloc] init];
+    shadow2.color = [UIColor blueColor];
+    shadow2.radius = 10.0;
+    shadow2.spread = 10.0;
+
+    appearance.shadows = @[shadow, shadow2];
+    fpc.surfaceView.appearance = appearance;
+}
+@end
+
+@implementation  MyFloatingPanelLayout
+- (FloatingPanelState *)initialState {
+    return FloatingPanelState.Half;
+}
+- (NSDictionary<FloatingPanelState *, id<FloatingPanelLayoutAnchoring>> *)anchors {
+    return @{
+        FloatingPanelState.Half: [[FloatingPanelLayoutAnchor alloc] initWithFractionalInset:0.5
+                                                                                       edge:FloatingPanelReferenceEdgeTop
+                                                                         referenceGuide:FloatingPanelLayoutReferenceGuideSafeArea],
+        FloatingPanelState.Tip: [[FloatingPanelLayoutAnchor alloc] initWithAbsoluteInset:44.0
+                                                                                    edge:FloatingPanelReferenceEdgeBottom
+                                                                         referenceGuide:FloatingPanelLayoutReferenceGuideSafeArea],
+    };
+}
+
+- (enum FloatingPanelPosition)position {
+    return FloatingPanelPositionBottom;
+}
+@end
+
+
+@implementation MyFloatingPanelBehavior
+@end

Examples/SamplesObjC/SamplesObjC/main.m

@@ -0,0 +1,10 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+#import <UIKit/UIKit.h>
+#import "AppDelegate.h"
+
+int main(int argc, char * argv[]) {
+    @autoreleasepool {
+        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
+    }
+}

Examples/Stocks/Stocks/AppDelegate.swift

@@ -1,10 +1,4 @@
-//
-//  AppDelegate.swift
-//  Stocks
-//
-//  Created by Shin Yamamoto on 2018/10/12.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import UIKit
 

Examples/Stocks/Stocks/ViewController.swift

@@ -1,10 +1,4 @@
-//
-//  ViewController.swift
-//  Stocks
-//
-//  Created by Shin Yamamoto on 2018/10/12.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import UIKit
 import FloatingPanel
@@ -18,19 +12,21 @@ class ViewController: UIViewController, FloatingPanelControllerDelegate {
     var newsVC: NewsViewController!
 
     var initialColor: UIColor = .black
+
     override func viewDidLoad() {
         super.viewDidLoad()
         initialColor = view.backgroundColor!
         // Initialize FloatingPanelController
         fpc = FloatingPanelController()
         fpc.delegate = self
+        fpc.behavior = FloatingPanelStocksBehavior()
 
         // Initialize FloatingPanelController and add the view
         fpc.surfaceView.backgroundColor = UIColor(displayP3Red: 30.0/255.0, green: 30.0/255.0, blue: 30.0/255.0, alpha: 1.0)
-        fpc.surfaceView.cornerRadius = 24.0
-        fpc.surfaceView.shadowHidden = true
-        fpc.surfaceView.borderWidth = 1.0 / traitCollection.displayScale
-        fpc.surfaceView.borderColor = UIColor.black.withAlphaComponent(0.2)
+        fpc.surfaceView.appearance.cornerRadius = 24.0
+        fpc.surfaceView.appearance.shadows = []
+        fpc.surfaceView.appearance.borderWidth = 1.0 / traitCollection.displayScale
+        fpc.surfaceView.appearance.borderColor = UIColor.black.withAlphaComponent(0.2)
 
         newsVC = storyboard?.instantiateViewController(withIdentifier: "News") as? NewsViewController
 
@@ -38,7 +34,7 @@ class ViewController: UIViewController, FloatingPanelControllerDelegate {
         fpc.set(contentViewController: newsVC)
         fpc.track(scrollView: newsVC.scrollView)
 
-        fpc.addPanel(toParent: self, belowView: bottomToolView, animated: false)
+        fpc.addPanel(toParent: self, at: view.subviews.firstIndex(of: bottomToolView) ?? -1 , animated: false)
 
         topBannerView.frame = .zero
         topBannerView.alpha = 0.0
@@ -50,46 +46,46 @@ class ViewController: UIViewController, FloatingPanelControllerDelegate {
             ])
     }
 
-    override func viewDidAppear(_ animated: Bool) {
-        super.viewDidAppear(animated)
-    }
-
-    override func viewDidDisappear(_ animated: Bool) {
-        super.viewDidDisappear(animated)
-    }
-
     override var preferredStatusBarStyle: UIStatusBarStyle {
         return .lightContent
     }
 
     // MARK: FloatingPanelControllerDelegate
 
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
         return FloatingPanelStocksLayout()
     }
 
-    func floatingPanel(_ vc: FloatingPanelController, behaviorFor newCollection: UITraitCollection) -> FloatingPanelBehavior? {
-        return FloatingPanelStocksBehavior()
-    }
+    func floatingPanelDidMove(_ vc: FloatingPanelController) {
+        if vc.isAttracting == false {
+            let loc = vc.surfaceLocation
+            let minY = vc.surfaceLocation(for: .full).y
+            let maxY = vc.surfaceLocation(for: .tip).y
+            vc.surfaceLocation = CGPoint(x: loc.x, y: min(max(loc.y, minY), maxY))
+        }
 
-    func floatingPanelWillBeginDragging(_ vc: FloatingPanelController) {
-        if vc.position == .full {
-            // Dimiss top bar with dissolve animation
-            UIView.animate(withDuration: 0.25) {
-                self.topBannerView.alpha = 0.0
-                self.labelStackView.alpha = 1.0
-                self.view.backgroundColor = self.initialColor
-            }
+        if vc.surfaceLocation.y <= vc.surfaceLocation(for: .full).y + 100 {
+            showStockTickerBanner()
+        } else {
+            hideStockTickerBanner()
         }
     }
-    func floatingPanelDidEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetPosition: FloatingPanelPosition) {
-        if targetPosition == .full {
-            // Present top bar with dissolve animation
-            UIView.animate(withDuration: 0.25) {
-                self.topBannerView.alpha = 1.0
-                self.labelStackView.alpha = 0.0
-                self.view.backgroundColor = .black
-            }
+
+    private func showStockTickerBanner() {
+        // Present top bar with dissolve animation
+        UIView.animate(withDuration: 0.25) {
+            self.topBannerView.alpha = 1.0
+            self.labelStackView.alpha = 0.0
+            self.view.backgroundColor = .black
+        }
+    }
+
+    private func hideStockTickerBanner() {
+        // Dimiss top bar with dissolve animation
+        UIView.animate(withDuration: 0.25) {
+            self.topBannerView.alpha = 0.0
+            self.labelStackView.alpha = 1.0
+            self.view.backgroundColor = .black
         }
     }
 }
@@ -99,57 +95,29 @@ class NewsViewController: UIViewController {
 }
 
 
-// MARK: My custom layout
+// MARK: - FloatingPanelLayout
 
 class FloatingPanelStocksLayout: FloatingPanelLayout {
-    var initialPosition: FloatingPanelPosition {
-        return .tip
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .tip
+
+    var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 56.0, edge: .top, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 262.0, edge: .bottom, referenceGuide: .safeArea),
+             /* Visible + ToolView */
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 85.0 + 44.0, edge: .bottom, referenceGuide: .safeArea),
+        ]
     }
 
-    var topInteractionBuffer: CGFloat { return 0.0 }
-    var bottomInteractionBuffer: CGFloat { return 0.0 }
-
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return 56.0
-        case .half: return 262.0
-        case .tip: return 85.0 + 44.0 // Visible + ToolView
-        default: return nil
-        }
-    }
-
-    func backdropAlphaFor(position: FloatingPanelPosition) -> CGFloat {
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
         return 0.0
     }
 }
 
-// MARK: My custom behavior
+// MARK: - FloatingPanelBehavior
 
 class FloatingPanelStocksBehavior: FloatingPanelBehavior {
-    var velocityThreshold: CGFloat {
-        return 15.0
-    }
-
-    func interactionAnimator(_ fpc: FloatingPanelController, to targetPosition: FloatingPanelPosition, with velocity: CGVector) -> UIViewPropertyAnimator {
-        let timing = timeingCurve(to: targetPosition, with: velocity)
-        return UIViewPropertyAnimator(duration: 0, timingParameters: timing)
-    }
-
-    private func timeingCurve(to: FloatingPanelPosition, with velocity: CGVector) -> UITimingCurveProvider {
-        let damping = self.damping(with: velocity)
-        return UISpringTimingParameters(dampingRatio: damping,
-                                        frequencyResponse: 0.4,
-                                        initialVelocity: velocity)
-    }
-
-    private func damping(with velocity: CGVector) -> CGFloat {
-        switch velocity.dy {
-        case ...(-velocityThreshold):
-            return 0.7
-        case velocityThreshold...:
-            return 0.7
-        default:
-            return 1.0
-        }
-    }
+    let springDecelerationRate: CGFloat = UIScrollView.DecelerationRate.fast.rawValue
+    let springResponseTime: CGFloat = 0.25
 }

FloatingPanel.podspec

@@ -1,23 +1,22 @@
 Pod::Spec.new do |s|
 
   s.name                = "FloatingPanel"
-  s.version             = "1.7.6"
+  s.version             = "2.0.1"
   s.summary             = "FloatingPanel is a clean and easy-to-use UI component of a floating panel interface."
   s.description         = <<-DESC
 FloatingPanel is a clean and easy-to-use UI component for a new interface introduced in Apple Maps, Shortcuts and Stocks app.
 The new interface displays the related contents and utilities in parallel as a user wants.
                    DESC
   s.homepage            = "https://github.com/SCENEE/FloatingPanel"
-  # s.screenshots       = ""
+  s.author              = "Shin Yamamoto"
+  s.social_media_url    = "https://twitter.com/scenee"
 
   s.platform            = :ios, "10.0"
-  s.source              = { :git => "https://github.com/SCENEE/FloatingPanel.git", :tag => "v#{s.version}" }
-  s.source_files        = "Framework/Sources/*.swift"
-  s.swift_versions      = ["4.0", "4.2", "5.0"]
+  s.source              = { :git => "https://github.com/SCENEE/FloatingPanel.git", :tag => s.version.to_s }
+  s.source_files        = "Sources/*.swift"
+  s.swift_versions      = ['5.1', '5.2', '5.3']
 
   s.framework           = "UIKit"
 
-  s.author              = { "Shin Yamamoto" => "shin@scenee.com" }
   s.license             = { :type => "MIT", :file => "LICENSE" }
-  s.social_media_url    = "https://twitter.com/scenee"
 end

FloatingPanel.xcodeproj/project.pbxproj

@@ -7,27 +7,32 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
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-		54352E9621A51A2500CBCA08 /* FloatingPanelTransitioning.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54352E9521A51A2500CBCA08 /* FloatingPanelTransitioning.swift */; };
-		54352E9821A521CA00CBCA08 /* FloatingPanelView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54352E9721A521CA00CBCA08 /* FloatingPanelView.swift */; };
-		5450EEE421646DF500135936 /* FloatingPanelBehavior.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5450EEE321646DF500135936 /* FloatingPanelBehavior.swift */; };
+		542753C622C49A6E00D17955 /* LayoutTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 542753C522C49A6E00D17955 /* LayoutTests.swift */; };
+		54352E9621A51A2500CBCA08 /* Transitioning.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54352E9521A51A2500CBCA08 /* Transitioning.swift */; };
+		54352E9821A521CA00CBCA08 /* PassThroughView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54352E9721A521CA00CBCA08 /* PassThroughView.swift */; };
+		5450EEE421646DF500135936 /* Behavior.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5450EEE321646DF500135936 /* Behavior.swift */; };
 		545DB9CB2151169500CA77B8 /* FloatingPanel.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 545DB9C12151169500CA77B8 /* FloatingPanel.framework */; };
-		545DB9D02151169500CA77B8 /* FloatingPanelControllerTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DB9CF2151169500CA77B8 /* FloatingPanelControllerTests.swift */; };
+		545DB9D02151169500CA77B8 /* ControllerTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DB9CF2151169500CA77B8 /* ControllerTests.swift */; };
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+		5469F4B424B30F3500537F8A /* LayoutReferences.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5469F4B324B30F3500537F8A /* LayoutReferences.swift */; };
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+		549E944522CF295D0050AECF /* StateTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 549E944422CF295D0050AECF /* StateTests.swift */; };
+		54A6B6B122968B530077F348 /* CoreTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54A6B6B022968B530077F348 /* CoreTests.swift */; };
+		54A6B6B82296A8520077F348 /* SurfaceViewTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54A6B6B72296A8520077F348 /* SurfaceViewTests.swift */; };
 		54ABD7AF216CCFF7002E6C13 /* Logger.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54ABD7AE216CCFF7002E6C13 /* Logger.swift */; };
-		54CDC5D3215B6D5A007D205C /* FloatingPanelSurfaceView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CDC5D2215B6D5A007D205C /* FloatingPanelSurfaceView.swift */; };
-		54CDC5D5215B6D8D007D205C /* FloatingPanelBackdropView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CDC5D4215B6D8D007D205C /* FloatingPanelBackdropView.swift */; };
-		54CFBFC3215CD045006B5735 /* FloatingPanelLayout.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CFBFC2215CD045006B5735 /* FloatingPanelLayout.swift */; };
-		54CFBFC5215CD09C006B5735 /* FloatingPanelCore.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CFBFC4215CD09C006B5735 /* FloatingPanelCore.swift */; };
-		54E740CD218AFD67005C1A34 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54E740CC218AFD67005C1A34 /* AppDelegate.swift */; };
+		54CDC5D3215B6D5A007D205C /* SurfaceView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CDC5D2215B6D5A007D205C /* SurfaceView.swift */; };
+		54CDC5D5215B6D8D007D205C /* BackdropView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CDC5D4215B6D8D007D205C /* BackdropView.swift */; };
+		54CFBFC3215CD045006B5735 /* Layout.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CFBFC2215CD045006B5735 /* Layout.swift */; };
+		54CFBFC5215CD09C006B5735 /* Core.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CFBFC4215CD09C006B5735 /* Core.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -48,32 +53,37 @@
 /* End PBXContainerItemProxy section */
 
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-		54352E9721A521CA00CBCA08 /* FloatingPanelView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FloatingPanelView.swift; sourceTree = "<group>"; };
-		5450EEE321646DF500135936 /* FloatingPanelBehavior.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FloatingPanelBehavior.swift; sourceTree = "<group>"; };
+		542753C522C49A6E00D17955 /* LayoutTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LayoutTests.swift; sourceTree = "<group>"; };
+		542753C722C49A8F00D17955 /* TestSupports.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TestSupports.swift; sourceTree = "<group>"; };
+		54352E9521A51A2500CBCA08 /* Transitioning.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Transitioning.swift; sourceTree = "<group>"; };
+		54352E9721A521CA00CBCA08 /* PassThroughView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PassThroughView.swift; sourceTree = "<group>"; };
+		5450EEE321646DF500135936 /* Behavior.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Behavior.swift; sourceTree = "<group>"; };
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@@ -107,7 +117,6 @@
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@@ -125,19 +134,23 @@
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-				54352E9521A51A2500CBCA08 /* FloatingPanelTransitioning.swift */,
-				54CFBFC4215CD09C006B5735 /* FloatingPanelCore.swift */,
-				54CFBFC2215CD045006B5735 /* FloatingPanelLayout.swift */,
-				5450EEE321646DF500135936 /* FloatingPanelBehavior.swift */,
-				54352E9721A521CA00CBCA08 /* FloatingPanelView.swift */,
-				54CDC5D2215B6D5A007D205C /* FloatingPanelSurfaceView.swift */,
-				54CDC5D4215B6D8D007D205C /* FloatingPanelBackdropView.swift */,
-				545DBA2A2152383100CA77B8 /* GrabberHandleView.swift */,
+				545DB9DF21511AC100CA77B8 /* Controller.swift */,
+				5469F4AD24B30D7E00537F8A /* State.swift */,
+				5469F4B124B30F1100537F8A /* Position.swift */,
+				54CFBFC4215CD09C006B5735 /* Core.swift */,
+				54CFBFC2215CD045006B5735 /* Layout.swift */,
+				5469F4B324B30F3500537F8A /* LayoutReferences.swift */,
+				5469F4AF24B30E1500537F8A /* LayoutAnchoring.swift */,
+				5450EEE321646DF500135936 /* Behavior.swift */,
+				54352E9721A521CA00CBCA08 /* PassThroughView.swift */,
+				54CDC5D2215B6D5A007D205C /* SurfaceView.swift */,
+				54CDC5D4215B6D8D007D205C /* BackdropView.swift */,
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+				54352E9521A51A2500CBCA08 /* Transitioning.swift */,
 				545DB9DD215118C800CA77B8 /* UIExtensions.swift */,
 				54ABD7AE216CCFF7002E6C13 /* Logger.swift */,
+				545DB9C42151169500CA77B8 /* FloatingPanel.h */,
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@@ -145,23 +158,25 @@
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-				54A6B6B72296A8520077F348 /* FloatingPanelSurfaceViewTests.swift */,
-				549E944422CF295D0050AECF /* FloatingPanelPositionTests.swift */,
-				542753C722C49A8F00D17955 /* Utils.swift */,
+				5469F49E24B003EF00537F8A /* TestingApp */,
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+				545DB9CF2151169500CA77B8 /* ControllerTests.swift */,
+				542753C522C49A6E00D17955 /* LayoutTests.swift */,
+				54A6B6B72296A8520077F348 /* SurfaceViewTests.swift */,
+				549E944422CF295D0050AECF /* StateTests.swift */,
+				549C371E2361E15D007D8058 /* UtilTests.swift */,
+				542753C722C49A8F00D17955 /* TestSupports.swift */,
 				545DB9D12151169500CA77B8 /* Info.plist */,
 			);
 			path = Tests;
 			sourceTree = "<group>";
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-		54E740CB218AFD67005C1A34 /* TestingApp */ = {
+		5469F49E24B003EF00537F8A /* TestingApp */ = {
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 			children = (
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-				54E740D8218AFD6A005C1A34 /* Info.plist */,
-				54A6B6B522968F710077F348 /* LaunchScreen.storyboard */,
+				5469F49F24B003EF00537F8A /* LaunchScreen.storyboard */,
+				5469F4A024B003EF00537F8A /* AppDelegate.swift */,
+				5469F4A124B003EF00537F8A /* Info.plist */,
 			);
 			path = TestingApp;
 			sourceTree = "<group>";
@@ -246,7 +261,7 @@
 				TargetAttributes = {
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-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1110;
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@@ -296,7 +311,7 @@
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 			files = (
-				54A6B6B622968F710077F348 /* LaunchScreen.storyboard in Resources */,
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@@ -307,17 +322,21 @@
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-				54352E9821A521CA00CBCA08 /* FloatingPanelView.swift in Sources */,
-				54CFBFC5215CD09C006B5735 /* FloatingPanelCore.swift in Sources */,
+				5469F4B224B30F1100537F8A /* Position.swift in Sources */,
+				5469F4B024B30E1500537F8A /* LayoutAnchoring.swift in Sources */,
+				54CDC5D3215B6D5A007D205C /* SurfaceView.swift in Sources */,
+				54CFBFC3215CD045006B5735 /* Layout.swift in Sources */,
+				5469F4B424B30F3500537F8A /* LayoutReferences.swift in Sources */,
+				54CDC5D5215B6D8D007D205C /* BackdropView.swift in Sources */,
+				54352E9821A521CA00CBCA08 /* PassThroughView.swift in Sources */,
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-				545DBA2B2152383100CA77B8 /* GrabberHandleView.swift in Sources */,
-				54352E9621A51A2500CBCA08 /* FloatingPanelTransitioning.swift in Sources */,
+				545DB9E021511AC100CA77B8 /* Controller.swift in Sources */,
+				5450EEE421646DF500135936 /* Behavior.swift in Sources */,
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+				54A6B6B82296A8520077F348 /* SurfaceViewTests.swift in Sources */,
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@@ -338,7 +358,7 @@
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@@ -417,6 +437,7 @@
 				SDKROOT = iphoneos;
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 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_VERSION = 5.0;
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
 			};
@@ -474,6 +495,7 @@
 				SDKROOT = iphoneos;
 				SWIFT_COMPILATION_MODE = wholemodule;
 				SWIFT_OPTIMIZATION_LEVEL = "-O";
+				SWIFT_VERSION = 5.0;
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 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
@@ -506,7 +528,7 @@
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 				SWIFT_COMPILATION_MODE = wholemodule;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 5.0;
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@@ -535,7 +557,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME:c99extidentifier)";
 				SKIP_INSTALL = YES;
 				SWIFT_COMPILATION_MODE = wholemodule;
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 5.0;
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 			name = Release;
@@ -587,7 +609,7 @@
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
 				DEVELOPMENT_TEAM = "";
-				INFOPLIST_FILE = TestingApp/Info.plist;
+				INFOPLIST_FILE = Tests/TestingApp/Info.plist;
 				IPHONEOS_DEPLOYMENT_TARGET = 10.0;
 				LD_RUNPATH_SEARCH_PATHS = (
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@@ -605,7 +627,7 @@
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
 				DEVELOPMENT_TEAM = "";
-				INFOPLIST_FILE = TestingApp/Info.plist;
+				INFOPLIST_FILE = Tests/TestingApp/Info.plist;
 				IPHONEOS_DEPLOYMENT_TARGET = 10.0;
 				LD_RUNPATH_SEARCH_PATHS = (
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@@ -677,6 +699,7 @@
 				SDKROOT = iphoneos;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_VERSION = 5.0;
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
 			};
@@ -705,9 +728,9 @@
 				PRODUCT_NAME = "$(TARGET_NAME:c99extidentifier)";
 				SKIP_INSTALL = YES;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = "TEST DEBUG __FP_LOG";
-				SWIFT_COMPILATION_MODE = wholemodule;
+				SWIFT_COMPILATION_MODE = singlefile;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
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 			name = Test;
@@ -737,7 +760,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				DEVELOPMENT_TEAM = "";
-				INFOPLIST_FILE = TestingApp/Info.plist;
+				INFOPLIST_FILE = Tests/TestingApp/Info.plist;
 				IPHONEOS_DEPLOYMENT_TARGET = 10.0;
 				LD_RUNPATH_SEARCH_PATHS = "@executable_path/Frameworks";
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FloatingPanel.xcodeproj/xcshareddata/IDETemplateMacros.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>FILEHEADER</key>
+	<string> Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.</string>
+</dict>
+</plist>

FloatingPanel.xcworkspace/contents.xcworkspacedata

@@ -4,13 +4,9 @@
    <FileRef
       location = "group:README.md">
    </FileRef>
-   <Group
-      location = "group:Framework"
-      name = "Framework">
-      <FileRef
-         location = "group:FloatingPanel.xcodeproj">
-      </FileRef>
-   </Group>
+   <FileRef
+      location = "group:FloatingPanel.xcodeproj">
+   </FileRef>
    <Group
       location = "group:Examples"
       name = "Examples">
@@ -23,5 +19,8 @@
       <FileRef
          location = "group:Samples/Samples.xcodeproj">
       </FileRef>
+      <FileRef
+         location = "group:SamplesObjC/SamplesObjC.xcodeproj">
+      </FileRef>
    </Group>
 </Workspace>

Framework/Sources/FloatingPanel.h

@@ -1,9 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2018/09/18.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
-
-#import <UIKit/UIKit.h>
-
-FOUNDATION_EXPORT double FloatingPanelVersionNumber;
-FOUNDATION_EXPORT const unsigned char FloatingPanelVersionString[];

Framework/Sources/FloatingPanelBackdropView.swift

@@ -1,11 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2018/09/26.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
-
-import UIKit
-
-/// A view that presents a backdrop interface behind a floating panel.
-public class FloatingPanelBackdropView: UIView {
-    public var dismissalTapGestureRecognizer: UITapGestureRecognizer!
-}

Framework/Sources/FloatingPanelBehavior.swift

@@ -1,156 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2018/10/03.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
-
-import UIKit
-
-public protocol FloatingPanelBehavior {
-    /// Asks the behavior if the floating panel should project a momentum of a user interaction to move the proposed position.
-    ///
-    /// The default implementation of this method returns true. This method is called for a layout to support all positions(tip, half and full).
-    /// Therefore, `proposedTargetPosition` can only be `FloatingPanelPosition.tip` or `FloatingPanelPosition.full`.
-    func shouldProjectMomentum(_ fpc: FloatingPanelController, for proposedTargetPosition: FloatingPanelPosition) -> Bool
-
-    /// Returns a deceleration rate to calculate a target position projected a dragging momentum.
-    ///
-    /// The default implementation of this method returns the normal deceleration rate of UIScrollView.
-    func momentumProjectionRate(_ fpc: FloatingPanelController) -> CGFloat
-
-    /// Returns the progress to redirect to the previous position.
-    ///
-    /// The progress is represented by a floating-point value between 0.0 and 1.0, inclusive, where 1.0 indicates the floating panel is impossible to move to the next position. The default value is 0.5. Values less than 0.0 and greater than 1.0 are pinned to those limits.
-    func redirectionalProgress(_ fpc: FloatingPanelController, from: FloatingPanelPosition, to: FloatingPanelPosition) -> CGFloat
-
-    /// Returns a UIViewPropertyAnimator object to project a floating panel to a position on finger up if the user dragged.
-    ///
-    /// - Attention:
-    /// By default, it returns a non-interruptible animator to prevent a propagation of the animation to a content view.
-    /// However returning an interruptible animator is working well depending on a content view and it can be better
-    /// than using a non-interruptible one.
-    func interactionAnimator(_ fpc: FloatingPanelController, to targetPosition: FloatingPanelPosition, with velocity: CGVector) -> UIViewPropertyAnimator
-
-    /// Returns a UIViewPropertyAnimator object to add a floating panel to a position.
-    ///
-    /// Its animator instance will be used to animate the surface view in `FloatingPanelController.addPanel(toParent:belowView:animated:)`.
-    /// Default is an animator with ease-in-out curve and 0.25 sec duration.
-    func addAnimator(_ fpc: FloatingPanelController, to: FloatingPanelPosition) -> UIViewPropertyAnimator
-
-    /// Returns a UIViewPropertyAnimator object to remove a floating panel from a position.
-    ///
-    /// Its animator instance will be used to animate the surface view in `FloatingPanelController.removePanelFromParent(animated:completion:)`.
-    /// Default is an animator with ease-in-out curve and 0.25 sec duration.
-    func removeAnimator(_ fpc: FloatingPanelController, from: FloatingPanelPosition) -> UIViewPropertyAnimator
-
-    /// Returns a UIViewPropertyAnimator object to move a floating panel from a position to a position.
-    ///
-    /// Its animator instance will be used to animate the surface view in `FloatingPanelController.move(to:animated:completion:)`.
-    /// Default is an animator with ease-in-out curve and 0.25 sec duration.
-    func moveAnimator(_ fpc: FloatingPanelController, from: FloatingPanelPosition, to: FloatingPanelPosition) -> UIViewPropertyAnimator
-
-    /// Returns a y-axis velocity to invoke a removal interaction at the bottom position.
-    ///
-    /// Default is 10.0. This method is called when FloatingPanelController.isRemovalInteractionEnabled is true.
-    var removalVelocity: CGFloat { get }
-
-    /// Returns the threshold of the transition to invoke a removal interaction at the bottom position.
-    ///
-    /// The progress is represented by a floating-point value between 0.0 and 1.0, inclusive, where 1.0 indicates the floating panel is impossible to invoke the removal interaction. The default value is 0.5. Values less than 0.0 and greater than 1.0 are pinned to those limits. This method is called when FloatingPanelController.isRemovalInteractionEnabled is true.
-    var removalProgress: CGFloat { get }
-
-    /// Returns a UIViewPropertyAnimator object to remove a floating panel with a velocity interactively at the bottom position.
-    ///
-    /// Default is a spring animator with 1.0 damping ratio. This method is called when FloatingPanelController.isRemovalInteractionEnabled is true.
-    func removalInteractionAnimator(_ fpc: FloatingPanelController, with velocity: CGVector) -> UIViewPropertyAnimator
-
-
-    /// Asks the behavior whether the rubber band effect is enabled in moving over a given edge of the surface view.
-    ///
-    /// This method allows the behavior to activate the rubber band effect to a given edge of the surface view. By default, the effect is disabled.
-    func allowsRubberBanding(for edge: UIRectEdge) -> Bool
-}
-
-public extension FloatingPanelBehavior {
-    func shouldProjectMomentum(_ fpc: FloatingPanelController, for proposedTargetPosition: FloatingPanelPosition) -> Bool {
-        return false
-    }
-
-    func momentumProjectionRate(_ fpc: FloatingPanelController) -> CGFloat {
-        #if swift(>=4.2)
-        return UIScrollView.DecelerationRate.normal.rawValue
-        #else
-        return UIScrollViewDecelerationRateNormal
-        #endif
-    }
-
-    func redirectionalProgress(_ fpc: FloatingPanelController, from: FloatingPanelPosition, to: FloatingPanelPosition) -> CGFloat {
-        return 0.5
-    }
-
-    func interactionAnimator(_ fpc: FloatingPanelController, to targetPosition: FloatingPanelPosition, with velocity: CGVector) -> UIViewPropertyAnimator {
-        return defaultBehavior.interactionAnimator(fpc, to: targetPosition, with: velocity)
-    }
-
-    func addAnimator(_ fpc: FloatingPanelController, to: FloatingPanelPosition) -> UIViewPropertyAnimator {
-        return UIViewPropertyAnimator(duration: 0.25, curve: .easeInOut)
-    }
-
-    func removeAnimator(_ fpc: FloatingPanelController, from: FloatingPanelPosition) -> UIViewPropertyAnimator {
-        return UIViewPropertyAnimator(duration: 0.25, curve: .easeInOut)
-    }
-
-    func moveAnimator(_ fpc: FloatingPanelController, from: FloatingPanelPosition, to: FloatingPanelPosition) -> UIViewPropertyAnimator {
-        return UIViewPropertyAnimator(duration: 0.25, curve: .easeInOut)
-    }
-
-    var removalVelocity: CGFloat {
-        return 10.0
-    }
-
-    var removalProgress: CGFloat {
-        return 0.5
-    }
-
-    func removalInteractionAnimator(_ fpc: FloatingPanelController, with velocity: CGVector) -> UIViewPropertyAnimator {
-        log.debug("velocity", velocity)
-        let timing = UISpringTimingParameters(dampingRatio: 1.0,
-                                        frequencyResponse: 0.3,
-                                        initialVelocity: velocity)
-        return UIViewPropertyAnimator(duration: 0, timingParameters: timing)
-    }
-
-    func allowsRubberBanding(for edge: UIRectEdge) -> Bool {
-        return false
-    }
-}
-
-private let defaultBehavior = FloatingPanelDefaultBehavior()
-
-public class FloatingPanelDefaultBehavior: FloatingPanelBehavior {
-    public init() { }
-
-    public func interactionAnimator(_ fpc: FloatingPanelController, to targetPosition: FloatingPanelPosition, with velocity: CGVector) -> UIViewPropertyAnimator {
-        let timing = timeingCurve(with: velocity)
-        let animator = UIViewPropertyAnimator(duration: 0, timingParameters: timing)
-        animator.isInterruptible = false // Prevent a propagation of the animation(spring etc) to a content view
-        return animator
-    }
-
-    private func timeingCurve(with velocity: CGVector) -> UITimingCurveProvider {
-        log.debug("velocity", velocity)
-        let damping = self.getDamping(with: velocity)
-        return UISpringTimingParameters(dampingRatio: damping,
-                                        frequencyResponse: 0.3,
-                                        initialVelocity: velocity)
-    }
-
-    private let velocityThreshold: CGFloat = 8.0
-    private func getDamping(with velocity: CGVector) -> CGFloat {
-        let dy = abs(velocity.dy)
-        if dy > velocityThreshold {
-            return 0.7
-        } else {
-            return 1.0
-        }
-    }
-}

Framework/Sources/FloatingPanelCore.swift

@@ -1,964 +0,0 @@
-//
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
-
-import UIKit
-import UIKit.UIGestureRecognizerSubclass // For Xcode 9.4.1
-
-///
-/// FloatingPanel presentation model
-///
-class FloatingPanelCore: NSObject, UIGestureRecognizerDelegate {
-    // MUST be a weak reference to prevent UI freeze on the presentation modally
-    weak var viewcontroller: FloatingPanelController?
-
-    let surfaceView: FloatingPanelSurfaceView
-    let backdropView: FloatingPanelBackdropView
-    var layoutAdapter: FloatingPanelLayoutAdapter
-    var behavior: FloatingPanelBehavior
-
-    weak var scrollView: UIScrollView? {
-        didSet {
-            oldValue?.panGestureRecognizer.removeTarget(self, action: nil)
-            scrollView?.panGestureRecognizer.addTarget(self, action: #selector(handle(panGesture:)))
-        }
-    }
-
-    private(set) var state: FloatingPanelPosition = .hidden {
-        didSet {
-            if let vc = viewcontroller {
-                vc.delegate?.floatingPanelDidChangePosition(vc)
-            }
-        }
-    }
-
-    private var isBottomState: Bool {
-        let remains = layoutAdapter.supportedPositions.filter { $0.rawValue > state.rawValue }
-        return remains.count == 0
-    }
-
-    let panGestureRecognizer: FloatingPanelPanGestureRecognizer
-    var isRemovalInteractionEnabled: Bool = false
-
-    fileprivate var animator: UIViewPropertyAnimator?
-
-    private var initialFrame: CGRect = .zero
-    private var initialTranslationY: CGFloat = 0
-    private var initialLocation: CGPoint = .nan
-
-    var interactionInProgress: Bool = false
-    var isDecelerating: Bool = false
-
-    // Scroll handling
-    private var initialScrollOffset: CGPoint = .zero
-    private var stopScrollDeceleration: Bool = false
-    private var scrollBouncable = false
-    private var scrollIndictorVisible = false
-
-    // MARK: - Interface
-
-    init(_ vc: FloatingPanelController, layout: FloatingPanelLayout, behavior: FloatingPanelBehavior) {
-        viewcontroller = vc
-
-        surfaceView = FloatingPanelSurfaceView()
-        surfaceView.backgroundColor = .white
-
-        backdropView = FloatingPanelBackdropView()
-        backdropView.backgroundColor = .black
-        backdropView.alpha = 0.0
-
-        self.layoutAdapter = FloatingPanelLayoutAdapter(surfaceView: surfaceView,
-                                                        backdropView: backdropView,
-                                                        layout: layout)
-        self.behavior = behavior
-
-        panGestureRecognizer = FloatingPanelPanGestureRecognizer()
-
-        if #available(iOS 11.0, *) {
-            panGestureRecognizer.name = "FloatingPanelSurface"
-        }
-
-        super.init()
-
-        panGestureRecognizer.floatingPanel = self
-        surfaceView.addGestureRecognizer(panGestureRecognizer)
-        panGestureRecognizer.addTarget(self, action: #selector(handle(panGesture:)))
-        panGestureRecognizer.delegate = self
-
-        // Set tap-to-dismiss in the backdrop view
-        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleBackdrop(tapGesture:)))
-        tapGesture.isEnabled = false
-        backdropView.dismissalTapGestureRecognizer = tapGesture
-        backdropView.addGestureRecognizer(tapGesture)
-    }
-
-    func move(to: FloatingPanelPosition, animated: Bool, completion: (() -> Void)? = nil) {
-        move(from: state, to: to, animated: animated, completion: completion)
-    }
-
-    private func move(from: FloatingPanelPosition, to: FloatingPanelPosition, animated: Bool, completion: (() -> Void)? = nil) {
-        assert(layoutAdapter.validPositions.contains(to), "Can't move to '\(to)' position because it's not valid in the layout")
-        guard let vc = viewcontroller else {
-            completion?()
-            return
-        }
-        if state != layoutAdapter.topMostState {
-            lockScrollView()
-        }
-        tearDownActiveInteraction()
-
-        if animated {
-            let animator: UIViewPropertyAnimator
-            switch (from, to) {
-            case (.hidden, let to):
-                animator = behavior.addAnimator(vc, to: to)
-            case (let from, .hidden):
-                animator = behavior.removeAnimator(vc, from: from)
-            case (let from, let to):
-                animator = behavior.moveAnimator(vc, from: from, to: to)
-            }
-
-            animator.addAnimations { [weak self] in
-                guard let `self` = self else { return }
-
-                self.state = to
-                self.updateLayout(to: to)
-            }
-            animator.addCompletion { [weak self] _ in
-                guard let `self` = self else { return }
-                self.animator = nil
-                if self.state == self.layoutAdapter.topMostState {
-                    self.unlockScrollView()
-                } else {
-                    self.lockScrollView()
-                }
-                completion?()
-            }
-            self.animator = animator
-            animator.startAnimation()
-        } else {
-            self.state = to
-            self.updateLayout(to: to)
-            if self.state == self.layoutAdapter.topMostState {
-                self.unlockScrollView()
-            } else {
-                self.lockScrollView()
-            }
-            completion?()
-        }
-    }
-
-    // MARK: - Layout update
-
-    private func updateLayout(to target: FloatingPanelPosition) {
-        self.layoutAdapter.activateFixedLayout()
-        self.layoutAdapter.activateInteractiveLayout(of: target)
-    }
-
-    func getBackdropAlpha(at currentY: CGFloat, with translation: CGPoint) -> CGFloat {
-        let forwardY = (translation.y >= 0)
-        let segment = layoutAdapter.segument(at: currentY, forward: forwardY)
-        let lowerPos = segment.lower ?? layoutAdapter.topMostState
-        let upperPos = segment.upper ?? layoutAdapter.bottomMostState
-
-        let pre = forwardY ? lowerPos : upperPos
-        let next = forwardY ? upperPos : lowerPos
-
-        let nextY = layoutAdapter.positionY(for: next)
-        let preY = layoutAdapter.positionY(for: pre)
-
-        let nextAlpha = layoutAdapter.layout.backdropAlphaFor(position: next)
-        let preAlpha = layoutAdapter.layout.backdropAlphaFor(position: pre)
-
-        if preY == nextY {
-            return preAlpha
-        } else {
-            return preAlpha + max(min(1.0, 1.0 - (nextY - currentY) / (nextY - preY) ), 0.0) * (nextAlpha - preAlpha)
-        }
-    }
-
-    // MARK: - UIGestureRecognizerDelegate
-
-    public func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer,
-                                  shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
-        guard gestureRecognizer == panGestureRecognizer else { return false }
-
-        /* log.debug("shouldRecognizeSimultaneouslyWith", otherGestureRecognizer) */
-
-        if let vc = viewcontroller,
-            vc.delegate?.floatingPanel(vc, shouldRecognizeSimultaneouslyWith: otherGestureRecognizer) ?? false {
-            return true
-        }
-
-        switch otherGestureRecognizer {
-        case is FloatingPanelPanGestureRecognizer:
-            // All visiable panels' pan gesture should be recognized simultaneously.
-            return true
-        case is UIPanGestureRecognizer,
-             is UISwipeGestureRecognizer,
-             is UIRotationGestureRecognizer,
-             is UIScreenEdgePanGestureRecognizer,
-             is UIPinchGestureRecognizer:
-            // all gestures of the tracking scroll view should be recognized in parallel
-            // and handle them in self.handle(panGesture:)
-            return scrollView?.gestureRecognizers?.contains(otherGestureRecognizer) ?? false
-        default:
-            // Should recognize tap/long press gestures in parallel when the surface view is at an anchor position.
-            let surfaceFrame = surfaceView.layer.presentation()?.frame ?? surfaceView.frame
-            let surfaceY = surfaceFrame.minY
-            let adapterY = layoutAdapter.positionY(for: state)
-
-            return abs(surfaceY - adapterY) < (1.0 / surfaceView.traitCollection.displayScale)
-        }
-    }
-
-    public func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldBeRequiredToFailBy otherGestureRecognizer: UIGestureRecognizer) -> Bool {
-        /* log.debug("shouldBeRequiredToFailBy", otherGestureRecognizer) */
-        if otherGestureRecognizer is FloatingPanelPanGestureRecognizer {
-            // If this panel is the farthest descendant of visiable panels,
-            // its ancestors' pan gesture must wait for its pan gesture to fail
-            if let view = otherGestureRecognizer.view, surfaceView.isDescendant(of: view) {
-                return true
-            }
-        }
-        if #available(iOS 11.0, *),
-            otherGestureRecognizer.name == "_UISheetInteractionBackgroundDismissRecognizer" {
-            // The dismiss gesture of a sheet modal should not begin until the pan gesture fails.
-            return true
-        }
-        return false
-    }
-
-    public func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
-        guard gestureRecognizer == panGestureRecognizer else { return false }
-
-        /* log.debug("shouldRequireFailureOf", otherGestureRecognizer) */
-
-        // Should begin the pan gesture without waiting for the tracking scroll view's gestures.
-        // `scrollView.gestureRecognizers` can contains the following gestures
-        // * UIScrollViewDelayedTouchesBeganGestureRecognizer
-        // * UIScrollViewPanGestureRecognizer (scrollView.panGestureRecognizer)
-        // * _UIDragAutoScrollGestureRecognizer
-        // * _UISwipeActionPanGestureRecognizer
-        // * UISwipeDismissalGestureRecognizer
-        if let scrollView = scrollView {
-            // On short contents scroll, `_UISwipeActionPanGestureRecognizer` blocks
-            // the panel's pan gesture if not returns false
-            if let scrollGestureRecognizers = scrollView.gestureRecognizers,
-                scrollGestureRecognizers.contains(otherGestureRecognizer) {
-                switch otherGestureRecognizer {
-                case scrollView.panGestureRecognizer:
-                    if grabberAreaFrame.contains(gestureRecognizer.location(in: gestureRecognizer.view)) {
-                        return false
-                    }
-                    return allowScrollPanGesture(for: scrollView)
-                default:
-                    return false
-                }
-            }
-        }
-
-        if let vc = viewcontroller,
-            vc.delegate?.floatingPanel(vc, shouldRecognizeSimultaneouslyWith: otherGestureRecognizer) ?? false {
-            return false
-        }
-
-        switch otherGestureRecognizer {
-        case is FloatingPanelPanGestureRecognizer:
-            // If this panel is the farthest descendant of visiable panels,
-            // its pan gesture does not require its ancestors' pan gesture to fail
-            if let view = otherGestureRecognizer.view, surfaceView.isDescendant(of: view) {
-                return false
-            }
-            return true
-        case is UIPanGestureRecognizer,
-             is UISwipeGestureRecognizer,
-             is UIRotationGestureRecognizer,
-             is UIScreenEdgePanGestureRecognizer,
-             is UIPinchGestureRecognizer:
-            if #available(iOS 11.0, *),
-                otherGestureRecognizer.name == "_UISheetInteractionBackgroundDismissRecognizer" {
-                // Should begin the pan gesture without waiting the dismiss gesture of a sheet modal.
-                return false
-            }
-            // Do not begin the pan gesture until these gestures fail
-            return true
-        default:
-            // Should begin the pan gesture without waiting tap/long press gestures fail
-            return false
-        }
-    }
-
-    var grabberAreaFrame: CGRect {
-        let grabberAreaFrame = CGRect(x: surfaceView.bounds.origin.x,
-                                     y: surfaceView.bounds.origin.y,
-                                     width: surfaceView.bounds.width,
-                                     height: surfaceView.topGrabberBarHeight * 2)
-        return grabberAreaFrame
-    }
-
-    // MARK: - Gesture handling
-
-    @objc func handleBackdrop(tapGesture: UITapGestureRecognizer) {
-        viewcontroller?.dismiss(animated: true) { [weak self] in
-            guard let vc = self?.viewcontroller else { return }
-            vc.delegate?.floatingPanelDidEndRemove(vc)
-        }
-    }
-
-    @objc func handle(panGesture: UIPanGestureRecognizer) {
-        let velocity = panGesture.velocity(in: panGesture.view)
-
-        switch panGesture {
-        case scrollView?.panGestureRecognizer:
-            guard let scrollView = scrollView else { return }
-
-            let location = panGesture.location(in: surfaceView)
-
-            let surfaceMinY = surfaceView.presentationFrame.minY
-            let adapterTopY = layoutAdapter.topY
-            let belowTop = surfaceMinY > (adapterTopY + (1.0 / surfaceView.traitCollection.displayScale))
-            log.debug("scroll gesture(\(state):\(panGesture.state)) --",
-                "belowTop = \(belowTop),",
-                "interactionInProgress = \(interactionInProgress),",
-                "scroll offset = \(scrollView.contentOffset.y),",
-                "location = \(location.y), velocity = \(velocity.y)")
-
-            let offset = scrollView.contentOffset.y - contentOrigin(of: scrollView).y
-
-            if belowTop {
-                // Scroll offset pinning
-                if state == layoutAdapter.topMostState {
-                    if interactionInProgress {
-                        log.debug("settle offset --", initialScrollOffset.y)
-                        scrollView.setContentOffset(initialScrollOffset, animated: false)
-                    } else {
-                        if grabberAreaFrame.contains(location) {
-                            // Preserve the current content offset in moving from full.
-                            scrollView.setContentOffset(initialScrollOffset, animated: false)
-                        }
-                    }
-                } else {
-                    scrollView.setContentOffset(initialScrollOffset, animated: false)
-                }
-
-                // Hide a scroll indicator at the non-top in dragging.
-                if interactionInProgress {
-                    lockScrollView()
-                } else {
-                    if state == layoutAdapter.topMostState, self.animator == nil,
-                        offset > 0, velocity.y < 0 {
-                        unlockScrollView()
-                    }
-                }
-            } else {
-                if interactionInProgress {
-                    // Show a scroll indicator at the top in dragging.
-                    if offset >= 0, velocity.y <= 0 {
-                        unlockScrollView()
-                    } else {
-                        if state == layoutAdapter.topMostState {
-                            // Adjust a small gap of the scroll offset just after swiping down starts in the grabber area.
-                            if grabberAreaFrame.contains(location), grabberAreaFrame.contains(initialLocation) {
-                                scrollView.setContentOffset(initialScrollOffset, animated: false)
-                            }
-                        }
-                    }
-                } else {
-                    if state == layoutAdapter.topMostState {
-                        // Hide a scroll indicator just before starting an interaction by swiping a panel down.
-                        if velocity.y > 0, !allowScrollPanGesture(for: scrollView) {
-                            lockScrollView()
-                        }
-                        // Show a scroll indicator when an animation is interrupted at the top and content is scrolled up
-                        if velocity.y < 0, allowScrollPanGesture(for: scrollView) {
-                            unlockScrollView()
-                        }
-
-                        // Adjust a small gap of the scroll offset just before swiping down starts in the grabber area,
-                        if grabberAreaFrame.contains(location), grabberAreaFrame.contains(initialLocation) {
-                            scrollView.setContentOffset(initialScrollOffset, animated: false)
-                        }
-                    }
-                }
-            }
-        case panGestureRecognizer:
-            let translation = panGesture.translation(in: panGestureRecognizer.view!.superview)
-            let location = panGesture.location(in: panGesture.view)
-
-            log.debug("panel gesture(\(state):\(panGesture.state)) --",
-                "translation =  \(translation.y), location = \(location.y), velocity = \(velocity.y)")
-
-            if interactionInProgress == false, isDecelerating == false,
-                let vc = viewcontroller, vc.delegate?.floatingPanelShouldBeginDragging(vc) == false {
-                return
-            }
-
-            if let animator = self.animator {
-                guard surfaceView.presentationFrame.minY >= layoutAdapter.topMaxY else { return }
-                log.debug("panel animation(interruptible: \(animator.isInterruptible)) interrupted!!!")
-                if animator.isInterruptible {
-                    animator.stopAnimation(false)
-                    // A user can stop a panel at the nearest Y of a target position so this fine-tunes
-                    // the a small gap between the presentation layer frame and model layer frame
-                    // to unlock scroll view properly at finishAnimation(at:)
-                    if abs(surfaceView.frame.minY - layoutAdapter.topY) <= 1.0 {
-                        surfaceView.frame.origin.y = layoutAdapter.topY
-                    }
-                    animator.finishAnimation(at: .current)
-                } else {
-                    self.endAnimation(false) // Must call it manually
-                }
-            }
-
-            if panGesture.state == .began {
-                panningBegan(at: location)
-                return
-            }
-
-            if shouldScrollViewHandleTouch(scrollView, point: location, velocity: velocity) {
-                return
-            }
-
-            switch panGesture.state {
-            case .changed:
-                if interactionInProgress == false {
-                    startInteraction(with: translation, at: location)
-                }
-                panningChange(with: translation)
-            case .ended, .cancelled, .failed:
-                if interactionInProgress == false {
-                    startInteraction(with: translation, at: location)
-                    // Workaround: Prevent stopping the surface view b/w anchors if the pan gesture
-                    // doesn't pass through .changed state after an interruptible animator is interrupted.
-                    let dy = translation.y - .leastNonzeroMagnitude
-                    layoutAdapter.updateInteractiveTopConstraint(diff: dy,
-                                                                 allowsTopBuffer: true,
-                                                                 with: behavior)
-                }
-                panningEnd(with: translation, velocity: velocity)
-            default:
-                break
-            }
-        default:
-            return
-        }
-    }
-
-    private func shouldScrollViewHandleTouch(_ scrollView: UIScrollView?, point: CGPoint, velocity: CGPoint) -> Bool {
-        // When no scrollView, nothing to handle.
-        guard let scrollView = scrollView else { return false }
-
-        // For _UISwipeActionPanGestureRecognizer
-        if let scrollGestureRecognizers = scrollView.gestureRecognizers {
-            for gesture in scrollGestureRecognizers {
-                guard gesture.state == .began || gesture.state == .changed
-                else { continue }
-
-                if gesture !=  scrollView.panGestureRecognizer {
-                    return true
-                }
-            }
-        }
-
-        guard
-            state == layoutAdapter.topMostState,   // When not top most(i.e. .full), don't scroll.
-            interactionInProgress == false,        // When interaction already in progress, don't scroll.
-            surfaceView.frame.minY == layoutAdapter.topY
-        else {
-            return false
-        }
-
-        // When the current and initial point within grabber area, do scroll.
-        if grabberAreaFrame.contains(point), !grabberAreaFrame.contains(initialLocation) {
-            return true
-        }
-
-        let scrollViewFrame = scrollView.convert(scrollView.bounds, to: surfaceView)
-        guard
-            scrollViewFrame.contains(initialLocation), // When initialLocation not in scrollView, don't scroll.
-            !grabberAreaFrame.contains(point)           // When point within grabber area, don't scroll.
-        else {
-            return false
-        }
-
-        let offset = scrollView.contentOffset.y - contentOrigin(of: scrollView).y
-        // The zero offset must be excluded because the offset is usually zero
-        // after a panel moves from half/tip to full.
-        if  offset > 0.0 {
-            return true
-        }
-        if scrollView.isDecelerating {
-            return true
-        }
-        if velocity.y <= 0 {
-            return true
-        }
-
-        return false
-    }
-
-    private func panningBegan(at location: CGPoint) {
-        // A user interaction does not always start from Began state of the pan gesture
-        // because it can be recognized in scrolling a content in a content view controller.
-        // So here just preserve the current state if needed.
-        log.debug("panningBegan -- location = \(location.y)")
-        initialLocation = location
-
-        guard let scrollView = scrollView else { return }
-        if state == layoutAdapter.topMostState {
-            if grabberAreaFrame.contains(location) {
-                initialScrollOffset = scrollView.contentOffset
-            }
-        } else {
-            initialScrollOffset = scrollView.contentOffset
-        }
-    }
-
-    private func panningChange(with translation: CGPoint) {
-        log.debug("panningChange -- translation = \(translation.y)")
-        let preY = surfaceView.frame.minY
-        let dy = translation.y - initialTranslationY
-
-        layoutAdapter.updateInteractiveTopConstraint(diff: dy,
-                                                     allowsTopBuffer: allowsTopBuffer(for: dy),
-                                                     with: behavior)
-
-        let currentY = surfaceView.frame.minY
-        backdropView.alpha = getBackdropAlpha(at: currentY, with: translation)
-        preserveContentVCLayoutIfNeeded()
-
-        let didMove = (preY != currentY)
-        guard didMove else { return }
-
-        if let vc = viewcontroller {
-            vc.delegate?.floatingPanelDidMove(vc)
-        }
-    }
-
-    private func allowsTopBuffer(for translationY: CGFloat) -> Bool {
-        let preY = surfaceView.frame.minY
-        let nextY = initialFrame.offsetBy(dx: 0.0, dy: translationY).minY
-        if let scrollView = scrollView, scrollView.panGestureRecognizer.state == .changed,
-            preY > 0 && preY > nextY {
-            return false
-        } else {
-            return true
-        }
-    }
-
-    private var disabledBottomAutoLayout = false
-    private var disabledAutoLayoutItems: Set<NSLayoutConstraint> = []
-    // Prevent stretching a view having a constraint to SafeArea.bottom in an overflow
-    // from the full position because SafeArea is global in a screen.
-    private func preserveContentVCLayoutIfNeeded() {
-        guard let vc = viewcontroller else { return }
-        guard vc.contentMode != .fitToBounds else { return }
-
-        // Must include topY
-        if (surfaceView.frame.minY <= layoutAdapter.topY) {
-            if !disabledBottomAutoLayout {
-                disabledAutoLayoutItems.removeAll()
-                vc.contentViewController?.view?.constraints.forEach({ (const) in
-                    switch vc.contentViewController?.layoutGuide.bottomAnchor {
-                    case const.firstAnchor:
-                        (const.secondItem as? UIView)?.disableAutoLayout()
-                        const.isActive = false
-                        disabledAutoLayoutItems.insert(const)
-                    case const.secondAnchor:
-                        (const.firstItem as? UIView)?.disableAutoLayout()
-                        const.isActive = false
-                        disabledAutoLayoutItems.insert(const)
-                    default:
-                        break
-                    }
-                })
-            }
-            disabledBottomAutoLayout = true
-        } else {
-            if disabledBottomAutoLayout {
-                disabledAutoLayoutItems.forEach({ (const) in
-                    switch vc.contentViewController?.layoutGuide.bottomAnchor {
-                    case const.firstAnchor:
-                        (const.secondItem as? UIView)?.enableAutoLayout()
-                        const.isActive = true
-                    case const.secondAnchor:
-                        (const.firstItem as? UIView)?.enableAutoLayout()
-                        const.isActive = true
-                    default:
-                        break
-                    }
-                })
-                disabledAutoLayoutItems.removeAll()
-            }
-            disabledBottomAutoLayout = false
-        }
-    }
-
-    private func panningEnd(with translation: CGPoint, velocity: CGPoint) {
-        log.debug("panningEnd -- translation = \(translation.y), velocity = \(velocity.y)")
-
-        if state == .hidden {
-            log.debug("Already hidden")
-            return
-        }
-
-        stopScrollDeceleration = surfaceView.frame.minY > (layoutAdapter.topY + (1.0 / surfaceView.traitCollection.displayScale)) // Projecting the dragging to the scroll dragging or not
-        if stopScrollDeceleration {
-            DispatchQueue.main.async { [weak self] in
-                guard let `self` = self else { return }
-                self.stopScrollingWithDeceleration(at: self.initialScrollOffset)
-            }
-        }
-
-        let currentY = surfaceView.frame.minY
-        let targetPosition = self.targetPosition(from: currentY, with: velocity)
-        let distance = self.distance(to: targetPosition)
-
-        endInteraction(for: targetPosition)
-
-        if isRemovalInteractionEnabled {
-            let velocityVector: CGVector
-            if distance == 0 {
-                velocityVector = .zero
-            } else {
-                let dy = min(velocity.y / abs(distance), behavior.removalVelocity)
-                velocityVector = CGVector(dx: 0, dy: dy)
-            }
-            // `velocityVector` will be replaced by just a velocity(not vector) when FloatingPanelRemovalInteraction will be added.
-            if shouldStartRemovalAnimation(with: velocityVector), let vc = viewcontroller {
-                if behavior.shouldProjectMomentum(vc, for: targetPosition) || isBottomState {
-                    vc.delegate?.floatingPanelDidEndDraggingToRemove(vc, withVelocity: velocity)
-                    let animationVector = CGVector(dx: abs(velocityVector.dx), dy: abs(velocityVector.dy))
-                    startRemovalAnimation(vc, with: animationVector) { [weak self] in
-                        self?.finishRemovalAnimation()
-                    }
-                    return
-                }
-            }
-        }
-
-        if scrollView != nil, !stopScrollDeceleration,
-            surfaceView.frame.minY == layoutAdapter.topY,
-            targetPosition == layoutAdapter.topMostState {
-            self.state = targetPosition
-            self.updateLayout(to: targetPosition)
-            self.unlockScrollView()
-            if let vc = viewcontroller {
-                vc.delegate?.floatingPanelDidEndDragging(vc, withVelocity: .zero, targetPosition: targetPosition)
-            }
-            return
-        }
-
-        if let vc = viewcontroller {
-            vc.delegate?.floatingPanelDidEndDragging(vc, withVelocity: velocity, targetPosition: targetPosition)
-        }
-
-        // Workaround: Disable a tracking scroll to prevent bouncing a scroll content in a panel animating
-        let isScrollEnabled = scrollView?.isScrollEnabled
-        if let scrollView = scrollView, targetPosition != .full {
-            scrollView.isScrollEnabled = false
-        }
-
-        startAnimation(to: targetPosition, at: distance, with: velocity)
-
-        // Workaround: Reset `self.scrollView.isScrollEnabled`
-        if let scrollView = scrollView, targetPosition != .full,
-            let isScrollEnabled = isScrollEnabled {
-            scrollView.isScrollEnabled = isScrollEnabled
-        }
-    }
-
-    private func shouldStartRemovalAnimation(with velocityVector: CGVector) -> Bool {
-        let posY = layoutAdapter.positionY(for: state)
-        let currentY = surfaceView.frame.minY
-        let hiddenY = layoutAdapter.positionY(for: .hidden)
-        let vth = behavior.removalVelocity
-        let pth = max(min(behavior.removalProgress, 1.0), 0.0)
-
-        let num = (currentY - posY)
-        let den = (hiddenY - posY)
-
-        guard num >= 0, den != 0, (num / den >= pth || velocityVector.dy == vth)
-        else { return false }
-
-        return true
-    }
-
-    private func startRemovalAnimation(_ vc: FloatingPanelController, with velocityVector: CGVector, completion: (() -> Void)?) {
-        let animator = behavior.removalInteractionAnimator(vc, with: velocityVector)
-
-        animator.addAnimations { [weak self] in
-            self?.state = .hidden
-            self?.updateLayout(to: .hidden)
-        }
-        animator.addCompletion({ _ in
-            self.animator = nil
-            completion?()
-        })
-        self.animator = animator
-        animator.startAnimation()
-    }
-
-    private func finishRemovalAnimation() {
-        viewcontroller?.dismiss(animated: false) { [weak self] in
-            guard let vc = self?.viewcontroller else { return }
-            vc.delegate?.floatingPanelDidEndRemove(vc)
-        }
-    }
-
-    private func startInteraction(with translation: CGPoint, at location: CGPoint) {
-        /* Don't lock a scroll view to show a scroll indicator after hitting the top */
-        log.debug("startInteraction  -- translation = \(translation.y), location = \(location.y)")
-        guard interactionInProgress == false else { return }
-
-        var offset: CGPoint = .zero
-
-        initialFrame = surfaceView.frame
-        if state == layoutAdapter.topMostState, let scrollView = scrollView {
-            if grabberAreaFrame.contains(location) {
-                initialScrollOffset = scrollView.contentOffset
-            } else {
-                initialScrollOffset = contentOrigin(of: scrollView)
-                // Fit the surface bounds to a scroll offset content by startInteraction(at:offset:)
-                let scrollOffsetY = (scrollView.contentOffset.y - contentOrigin(of: scrollView).y)
-                if scrollOffsetY < 0 {
-                    offset = CGPoint(x: -scrollView.contentOffset.x, y: -scrollOffsetY)
-                }
-            }
-            log.debug("initial scroll offset --", initialScrollOffset)
-        }
-
-        initialTranslationY = translation.y
-
-        if let vc = viewcontroller {
-            vc.delegate?.floatingPanelWillBeginDragging(vc)
-        }
-
-        layoutAdapter.startInteraction(at: state, offset: offset)
-
-        interactionInProgress = true
-
-        lockScrollView()
-    }
-
-    private func endInteraction(for targetPosition: FloatingPanelPosition) {
-        log.debug("endInteraction to \(targetPosition)")
-
-        if let scrollView = scrollView {
-            log.debug("endInteraction -- scroll offset = \(scrollView.contentOffset)")
-        }
-
-        interactionInProgress = false
-
-        // Prevent to keep a scroll view indicator visible at the half/tip position
-        if targetPosition != layoutAdapter.topMostState {
-            lockScrollView()
-        }
-
-        layoutAdapter.endInteraction(at: targetPosition)
-    }
-
-    private func tearDownActiveInteraction() {
-        // Cancel the pan gesture so that panningEnd(with:velocity:) is called
-        panGestureRecognizer.isEnabled = false
-        panGestureRecognizer.isEnabled = true
-    }
-
-    private func startAnimation(to targetPosition: FloatingPanelPosition, at distance: CGFloat, with velocity: CGPoint) {
-        log.debug("startAnimation to \(targetPosition) -- distance = \(distance), velocity = \(velocity.y)")
-        guard let vc = viewcontroller else { return }
-
-        isDecelerating = true
-
-        vc.delegate?.floatingPanelWillBeginDecelerating(vc)
-
-        let velocityVector = (distance != 0) ? CGVector(dx: 0, dy: velocity.y / distance) : .zero
-        let animator = behavior.interactionAnimator(vc, to: targetPosition, with: velocityVector)
-        animator.addAnimations { [weak self] in
-            guard let `self` = self, let vc = self.viewcontroller else { return }
-            self.state = targetPosition
-            if animator.isInterruptible {
-                switch vc.contentMode {
-                case .fitToBounds:
-                    UIView.performWithLinear(startTime: 0.0, relativeDuration: 0.75) {
-                        self.layoutAdapter.activateFixedLayout()
-                        self.surfaceView.superview!.layoutIfNeeded()
-                    }
-                case .static:
-                    self.layoutAdapter.activateFixedLayout()
-                }
-            } else {
-                self.layoutAdapter.activateFixedLayout()
-            }
-            self.layoutAdapter.activateInteractiveLayout(of: targetPosition)
-        }
-        animator.addCompletion { [weak self] pos in
-            // Prevent calling `finishAnimation(at:)` by the old animator whose `isInterruptive` is false
-            // when a new animator has been started after the old one is interrupted.
-            guard let `self` = self, self.animator == animator else { return }
-            log.debug("finishAnimation to \(targetPosition)")
-            self.endAnimation(pos == .end)
-        }
-        self.animator = animator
-        animator.startAnimation()
-    }
-
-    private func endAnimation(_ finished: Bool) {
-        self.isDecelerating = false
-        self.animator = nil
-
-        if let vc = viewcontroller {
-            vc.delegate?.floatingPanelDidEndDecelerating(vc)
-        }
-
-        if let scrollView = scrollView {
-            log.debug("finishAnimation -- scroll offset = \(scrollView.contentOffset)")
-        }
-
-        stopScrollDeceleration = false
-
-        log.debug("finishAnimation -- state = \(state) surface.minY = \(surfaceView.presentationFrame.minY) topY = \(layoutAdapter.topY)")
-        if finished, state == layoutAdapter.topMostState, abs(surfaceView.presentationFrame.minY - layoutAdapter.topY) <= 1.0 {
-            unlockScrollView()
-        }
-    }
-
-    private func distance(to targetPosition: FloatingPanelPosition) -> CGFloat {
-        let currentY = surfaceView.frame.minY
-        let targetY = layoutAdapter.positionY(for: targetPosition)
-        return CGFloat(targetY - currentY)
-    }
-
-    // Distance travelled after decelerating to zero velocity at a constant rate.
-    // Refer to the slides p176 of [Designing Fluid Interfaces](https://developer.apple.com/videos/play/wwdc2018/803/)
-    private func project(initialVelocity: CGFloat, decelerationRate: CGFloat) -> CGFloat {
-        return (initialVelocity / 1000.0) * decelerationRate / (1.0 - decelerationRate)
-    }
-
-    func targetPosition(from currentY: CGFloat, with velocity: CGPoint) -> (FloatingPanelPosition) {
-        guard let vc = viewcontroller else { return state }
-        let supportedPositions = layoutAdapter.supportedPositions
-
-        guard supportedPositions.count > 1 else {
-            return state
-        }
-
-        let sortedPositions = Array(supportedPositions).sorted(by: { $0.rawValue < $1.rawValue })
-
-        // Projection
-        let decelerationRate = behavior.momentumProjectionRate(vc)
-        let baseY = abs(layoutAdapter.positionY(for: layoutAdapter.bottomMostState) - layoutAdapter.positionY(for: layoutAdapter.topMostState))
-        let vecY = velocity.y / baseY
-        var pY = project(initialVelocity: vecY, decelerationRate: decelerationRate) * baseY + currentY
-
-        let forwardY = velocity.y == 0 ? (currentY - layoutAdapter.positionY(for: state) > 0) : velocity.y > 0
-
-        let segment = layoutAdapter.segument(at: pY, forward: forwardY)
-
-        var fromPos: FloatingPanelPosition
-        var toPos: FloatingPanelPosition
-
-        let (lowerPos, upperPos) = (segment.lower ?? sortedPositions.first!, segment.upper ?? sortedPositions.last!)
-        (fromPos, toPos) = forwardY ? (lowerPos, upperPos) : (upperPos, lowerPos)
-
-        if behavior.shouldProjectMomentum(vc, for: toPos) == false {
-            let segment = layoutAdapter.segument(at: currentY, forward: forwardY)
-            var (lowerPos, upperPos) = (segment.lower ?? sortedPositions.first!, segment.upper ?? sortedPositions.last!)
-            // Equate the segment out of {top,bottom} most state to the {top,bottom} most segment
-            if lowerPos == upperPos {
-                if forwardY {
-                    upperPos = lowerPos.next(in: sortedPositions)
-                } else {
-                    lowerPos = upperPos.pre(in: sortedPositions)
-                }
-            }
-            (fromPos, toPos) = forwardY ? (lowerPos, upperPos) : (upperPos, lowerPos)
-            // Block a projection to a segment over the next from the current segment
-            // (= Trim pY with the current segment)
-            if forwardY {
-                pY = max(min(pY, layoutAdapter.positionY(for: toPos.next(in: sortedPositions))), layoutAdapter.positionY(for: fromPos))
-            } else {
-                pY = max(min(pY, layoutAdapter.positionY(for: fromPos)), layoutAdapter.positionY(for: toPos.pre(in: sortedPositions)))
-            }
-        }
-
-        // Redirection
-        let redirectionalProgress = max(min(behavior.redirectionalProgress(vc, from: fromPos, to: toPos), 1.0), 0.0)
-        let progress = abs(pY - layoutAdapter.positionY(for: fromPos)) / abs(layoutAdapter.positionY(for: fromPos) - layoutAdapter.positionY(for: toPos))
-        return progress > redirectionalProgress ? toPos : fromPos
-    }
-
-    // MARK: - ScrollView handling
-
-    private func lockScrollView() {
-        guard let scrollView = scrollView else { return }
-
-        if scrollView.isLocked {
-            log.debug("Already scroll locked.")
-            return
-        }
-        log.debug("lock scroll view")
-
-        scrollBouncable = scrollView.bounces
-        scrollIndictorVisible = scrollView.showsVerticalScrollIndicator
-
-        scrollView.isDirectionalLockEnabled = true
-        scrollView.bounces = false
-        scrollView.showsVerticalScrollIndicator = false
-    }
-
-    private func unlockScrollView() {
-        guard let scrollView = scrollView, scrollView.isLocked else { return }
-        log.debug("unlock scroll view")
-
-        scrollView.isDirectionalLockEnabled = false
-        scrollView.bounces = scrollBouncable
-        scrollView.showsVerticalScrollIndicator = scrollIndictorVisible
-    }
-
-    private func stopScrollingWithDeceleration(at contentOffset: CGPoint) {
-        // Must use setContentOffset(_:animated) to force-stop deceleration
-        scrollView?.setContentOffset(contentOffset, animated: false)
-    }
-
-    private func contentOrigin(of scrollView: UIScrollView) -> CGPoint {
-        if let vc = viewcontroller, let origin = vc.delegate?.floatingPanel(vc, contentOffsetForPinning: scrollView) {
-            return origin
-        }
-        return CGPoint(x: 0.0, y: 0.0 - scrollView.contentInset.top)
-    }
-
-    private func allowScrollPanGesture(for scrollView: UIScrollView) -> Bool {
-        let contentOffset = scrollView.contentOffset - contentOrigin(of: scrollView)
-        if state == layoutAdapter.topMostState {
-            return contentOffset.y <= -30.0 || contentOffset.y > 0
-        }
-        return false
-    }
-}
-
-class FloatingPanelPanGestureRecognizer: UIPanGestureRecognizer {
-    fileprivate weak var floatingPanel: FloatingPanelCore?
-    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
-        super.touchesBegan(touches, with: event)
-        if floatingPanel?.animator != nil {
-            self.state = .began
-        }
-    }
-    override weak var delegate: UIGestureRecognizerDelegate? {
-        get {
-            return super.delegate
-        }
-        set {
-            guard newValue is FloatingPanelCore else {
-                let exception = NSException(name: .invalidArgumentException,
-                                            reason: "FloatingPanelController's built-in pan gesture recognizer must have its controller as its delegate.",
-                                            userInfo: nil)
-                exception.raise()
-                return
-            }
-            super.delegate = newValue
-        }
-    }
-}

Framework/Sources/FloatingPanelLayout.swift

@@ -1,616 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2018/09/27.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
-
-import UIKit
-
-/// FloatingPanelFullScreenLayout
-///
-/// Use the layout protocol if you configure full, half and tip insets from the superview, not the safe area.
-/// It can't be used with FloatingPanelIntrinsicLayout.
-public protocol FloatingPanelFullScreenLayout: FloatingPanelLayout { }
-
-public extension FloatingPanelFullScreenLayout {
-    var positionReference: FloatingPanelLayoutReference {
-        return .fromSuperview
-    }
-}
-
-/// FloatingPanelIntrinsicLayout
-///
-/// Use the layout protocol if you want to layout a panel using the intrinsic height.
-/// It can't be used with `FloatingPanelFullScreenLayout`.
-///
-/// - Attention:
-///     `insetFor(position:)` must return `nil` for the full position. Because
-///     the inset is determined automatically by the intrinsic height.
-///     You can customize insets only for the half, tip and hidden positions.
-///
-/// - Note:
-///     By default, the `positionReference` is set to `.fromSafeArea`.
-public protocol FloatingPanelIntrinsicLayout: FloatingPanelLayout { }
-
-public extension FloatingPanelIntrinsicLayout {
-    var initialPosition: FloatingPanelPosition {
-        return .full
-    }
-
-    var supportedPositions: Set<FloatingPanelPosition> {
-        return [.full]
-    }
-
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        return nil
-    }
-
-    var positionReference: FloatingPanelLayoutReference {
-        return .fromSafeArea
-    }
-}
-
-public enum FloatingPanelLayoutReference: Int {
-    case fromSafeArea = 0
-    case fromSuperview = 1
-}
-
-public protocol FloatingPanelLayout: class {
-    /// Returns the initial position of a floating panel.
-    var initialPosition: FloatingPanelPosition { get }
-
-    /// Returns a set of FloatingPanelPosition objects to tell the applicable
-    /// positions of the floating panel controller.
-    ///
-    /// By default, it returns full, half and tip positions.
-    var supportedPositions: Set<FloatingPanelPosition> { get }
-
-    /// Return the interaction buffer to the top from the top position. Default is 6.0.
-    var topInteractionBuffer: CGFloat { get }
-
-    /// Return the interaction buffer to the bottom from the bottom position. Default is 6.0.
-    ///
-    /// - Important:
-    /// The specified buffer is ignored when `FloatingPanelController.isRemovalInteractionEnabled` is set to true.
-    var bottomInteractionBuffer: CGFloat { get }
-
-    /// Returns a CGFloat value to determine a Y coordinate of a floating panel for each position(full, half, tip and hidden).
-    ///
-    /// Its returning value indicates a different inset for each position.
-    /// For full position, a top inset from a safe area in `FloatingPanelController.view`.
-    /// For half or tip position, a bottom inset from the safe area.
-    /// For hidden position, a bottom inset from `FloatingPanelController.view`.
-    /// If a position isn't supported or the default value is used, return nil.
-    func insetFor(position: FloatingPanelPosition) -> CGFloat?
-
-    /// Returns X-axis and width layout constraints of the surface view of a floating panel.
-    /// You must not include any Y-axis and height layout constraints of the surface view
-    /// because their constraints will be configured by the floating panel controller.
-    /// By default, the width of a surface view fits a safe area.
-    func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint]
-
-    /// Returns a CGFloat value to determine the backdrop view's alpha for a position.
-    ///
-    /// Default is 0.3 at full position, otherwise 0.0.
-    func backdropAlphaFor(position: FloatingPanelPosition) -> CGFloat
-
-    var positionReference: FloatingPanelLayoutReference { get }
-
-}
-
-public extension FloatingPanelLayout {
-    var topInteractionBuffer: CGFloat { return 6.0 }
-    var bottomInteractionBuffer: CGFloat { return 6.0 }
-
-    var supportedPositions: Set<FloatingPanelPosition> {
-        return Set([.full, .half, .tip])
-    }
-
-    func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
-        return [
-            surfaceView.leftAnchor.constraint(equalTo: view.sideLayoutGuide.leftAnchor, constant: 0.0),
-            surfaceView.rightAnchor.constraint(equalTo: view.sideLayoutGuide.rightAnchor, constant: 0.0),
-        ]
-    }
-
-    func backdropAlphaFor(position: FloatingPanelPosition) -> CGFloat {
-        return position == .full ? 0.3 : 0.0
-    }
-
-    var positionReference: FloatingPanelLayoutReference {
-        return .fromSafeArea
-    }
-}
-
-public class FloatingPanelDefaultLayout: FloatingPanelLayout {
-    public init() { }
-
-    public var initialPosition: FloatingPanelPosition {
-        return .half
-    }
-
-    public func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return 18.0
-        case .half: return 262.0
-        case .tip: return 69.0
-        case .hidden: return nil
-        }
-    }
-}
-
-public class FloatingPanelDefaultLandscapeLayout: FloatingPanelLayout {
-    public init() { }
-
-    public var initialPosition: FloatingPanelPosition {
-        return .tip
-    }
-    public var supportedPositions: Set<FloatingPanelPosition> {
-        return [.full, .tip]
-    }
-
-    public func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return 16.0
-        case .tip: return 69.0
-        default: return nil
-        }
-    }
-}
-
-struct LayoutSegment {
-    let lower: FloatingPanelPosition?
-    let upper: FloatingPanelPosition?
-}
-
-class FloatingPanelLayoutAdapter {
-    weak var vc: FloatingPanelController!
-    private weak var surfaceView: FloatingPanelSurfaceView!
-    private weak var backdropView: FloatingPanelBackdropView!
-
-    var layout: FloatingPanelLayout {
-        didSet {
-            checkLayoutConsistance()
-        }
-    }
-
-    private var safeAreaInsets: UIEdgeInsets {
-        return vc?.layoutInsets ?? .zero
-    }
-
-    private var initialConst: CGFloat = 0.0
-
-    private var fixedConstraints: [NSLayoutConstraint] = []
-    private var fullConstraints: [NSLayoutConstraint] = []
-    private var halfConstraints: [NSLayoutConstraint] = []
-    private var tipConstraints: [NSLayoutConstraint] = []
-    private var offConstraints: [NSLayoutConstraint] = []
-    private var interactiveTopConstraint: NSLayoutConstraint?
-    private var bottomConstraint: NSLayoutConstraint?
-
-
-    private var heightConstraint: NSLayoutConstraint?
-
-    private var fullInset: CGFloat {
-        if layout is FloatingPanelIntrinsicLayout {
-            return intrinsicHeight
-        } else {
-            return layout.insetFor(position: .full) ?? 0.0
-        }
-    }
-    private var halfInset: CGFloat {
-        return layout.insetFor(position: .half) ?? 0.0
-    }
-    private var tipInset: CGFloat {
-        return layout.insetFor(position: .tip) ?? 0.0
-    }
-    private var hiddenInset: CGFloat {
-        return layout.insetFor(position: .hidden) ?? 0.0
-    }
-
-    var supportedPositions: Set<FloatingPanelPosition> {
-        return layout.supportedPositions
-    }
-
-    var validPositions: Set<FloatingPanelPosition> {
-        return supportedPositions.union([.hidden])
-    }
-
-    var topMostState: FloatingPanelPosition {
-        return supportedPositions.sorted(by: { $0.rawValue < $1.rawValue }).first ?? .hidden
-    }
-
-    var bottomMostState: FloatingPanelPosition {
-        return supportedPositions.sorted(by: { $0.rawValue < $1.rawValue }).last ?? .hidden
-    }
-
-    var topY: CGFloat {
-        return positionY(for: topMostState)
-    }
-
-    var bottomY: CGFloat {
-        return positionY(for: bottomMostState)
-    }
-
-    var topMaxY: CGFloat {
-        return topY - layout.topInteractionBuffer
-    }
-
-    var bottomMaxY: CGFloat {
-        return bottomY + layout.bottomInteractionBuffer
-    }
-
-    var adjustedContentInsets: UIEdgeInsets {
-        return UIEdgeInsets(top: 0.0,
-                            left: 0.0,
-                            bottom: safeAreaInsets.bottom,
-                            right: 0.0)
-    }
-
-    func positionY(for pos: FloatingPanelPosition) -> CGFloat {
-        switch pos {
-        case .full:
-            if layout is FloatingPanelIntrinsicLayout {
-                return surfaceView.superview!.bounds.height - surfaceView.bounds.height
-            }
-            switch layout.positionReference {
-            case .fromSafeArea:
-                return (safeAreaInsets.top + fullInset)
-            case .fromSuperview:
-                return fullInset
-            }
-        case .half:
-            switch layout.positionReference {
-            case .fromSafeArea:
-                return surfaceView.superview!.bounds.height - (safeAreaInsets.bottom + halfInset)
-            case .fromSuperview:
-                return surfaceView.superview!.bounds.height - halfInset
-            }
-        case .tip:
-            switch layout.positionReference {
-            case .fromSafeArea:
-                return surfaceView.superview!.bounds.height - (safeAreaInsets.bottom + tipInset)
-            case .fromSuperview:
-                return surfaceView.superview!.bounds.height - tipInset
-            }
-        case .hidden:
-            return surfaceView.superview!.bounds.height - hiddenInset
-        }
-    }
-
-    var intrinsicHeight: CGFloat = 0.0
-
-    init(surfaceView: FloatingPanelSurfaceView, backdropView: FloatingPanelBackdropView, layout: FloatingPanelLayout) {
-        self.layout = layout
-        self.surfaceView = surfaceView
-        self.backdropView = backdropView
-    }
-
-    func updateIntrinsicHeight() {
-        #if swift(>=4.2)
-        let fittingSize = UIView.layoutFittingCompressedSize
-        #else
-        let fittingSize = UILayoutFittingCompressedSize
-        #endif
-        var intrinsicHeight = surfaceView.contentView?.systemLayoutSizeFitting(fittingSize).height ?? 0.0
-        var safeAreaBottom: CGFloat = 0.0
-        if #available(iOS 11.0, *) {
-            safeAreaBottom = surfaceView.contentView?.safeAreaInsets.bottom ?? 0.0
-            if safeAreaBottom > 0 {
-                intrinsicHeight -= safeAreaInsets.bottom
-            }
-        }
-        self.intrinsicHeight = max(intrinsicHeight, 0.0)
-
-        log.debug("Update intrinsic height =", intrinsicHeight,
-                  ", surface(height) =", surfaceView.frame.height,
-                  ", content(height) =", surfaceView.contentView?.frame.height ?? 0.0,
-                  ", content safe area(bottom) =", safeAreaBottom)
-    }
-
-    func prepareLayout(in vc: FloatingPanelController) {
-        self.vc = vc
-
-        NSLayoutConstraint.deactivate(fixedConstraints + fullConstraints + halfConstraints + tipConstraints + offConstraints)
-        NSLayoutConstraint.deactivate(constraint: self.heightConstraint)
-        self.heightConstraint = nil
-        NSLayoutConstraint.deactivate(constraint: self.bottomConstraint)
-        self.bottomConstraint = nil
-
-        surfaceView.translatesAutoresizingMaskIntoConstraints = false
-        backdropView.translatesAutoresizingMaskIntoConstraints = false
-
-        // Fixed constraints of surface and backdrop views
-        let surfaceConstraints = layout.prepareLayout(surfaceView: surfaceView, in: vc.view!)
-        let backdropConstraints = [
-            backdropView.topAnchor.constraint(equalTo: vc.view.topAnchor, constant: 0.0),
-            backdropView.leftAnchor.constraint(equalTo: vc.view.leftAnchor,constant: 0.0),
-            backdropView.rightAnchor.constraint(equalTo: vc.view.rightAnchor, constant: 0.0),
-            backdropView.bottomAnchor.constraint(equalTo: vc.view.bottomAnchor, constant: 0.0),
-            ]
-
-        fixedConstraints = surfaceConstraints + backdropConstraints
-
-        if vc.contentMode == .fitToBounds {
-            bottomConstraint = surfaceView.bottomAnchor.constraint(equalTo: vc.view.bottomAnchor,
-                                                                   constant: 0.0)
-        }
-
-        // Flexible surface constraints for full, half, tip and off
-        let topAnchor: NSLayoutYAxisAnchor = {
-            if layout.positionReference == .fromSuperview {
-                return vc.view.topAnchor
-            } else {
-                return vc.layoutGuide.topAnchor
-            }
-        }()
-
-        switch layout {
-        case is FloatingPanelIntrinsicLayout:
-            // Set up on updateHeight()
-            break
-        default:
-            fullConstraints = [
-                surfaceView.topAnchor.constraint(equalTo: topAnchor,
-                                                 constant: fullInset),
-            ]
-        }
-
-        let bottomAnchor: NSLayoutYAxisAnchor = {
-            if layout.positionReference == .fromSuperview {
-                return vc.view.bottomAnchor
-            } else {
-                return vc.layoutGuide.bottomAnchor
-            }
-        }()
-
-        halfConstraints = [
-            surfaceView.topAnchor.constraint(equalTo: bottomAnchor,
-                                             constant: -halfInset),
-        ]
-        tipConstraints = [
-            surfaceView.topAnchor.constraint(equalTo: bottomAnchor,
-                                             constant: -tipInset),
-        ]
-
-        offConstraints = [
-            surfaceView.topAnchor.constraint(equalTo:vc.view.bottomAnchor,
-                                             constant: -hiddenInset),
-        ]
-    }
-
-    func startInteraction(at state: FloatingPanelPosition, offset: CGPoint = .zero) {
-        guard self.interactiveTopConstraint == nil else { return }
-        NSLayoutConstraint.deactivate(fullConstraints + halfConstraints + tipConstraints + offConstraints)
-
-        let interactiveTopConstraint: NSLayoutConstraint
-        switch layout.positionReference {
-        case .fromSafeArea:
-            initialConst = surfaceView.frame.minY - safeAreaInsets.top + offset.y
-            interactiveTopConstraint = surfaceView.topAnchor.constraint(equalTo: vc.layoutGuide.topAnchor,
-                                                                        constant: initialConst)
-        case .fromSuperview:
-            initialConst = surfaceView.frame.minY + offset.y
-            interactiveTopConstraint = surfaceView.topAnchor.constraint(equalTo: vc.view.topAnchor,
-                                                                        constant: initialConst)
-        }
-        NSLayoutConstraint.activate([interactiveTopConstraint])
-        self.interactiveTopConstraint = interactiveTopConstraint
-    }
-
-    func endInteraction(at state: FloatingPanelPosition) {
-        // Don't deactivate `interactiveTopConstraint` here because it leads to
-        // unsatisfiable constraints
-
-        if self.interactiveTopConstraint == nil {
-            // Activate `interactiveTopConstraint` for `fitToBounds` mode.
-            // It goes through this path when the pan gesture state jumps
-            // from .begin to .end.
-            startInteraction(at: state)
-        }
-    }
-
-    // The method is separated from prepareLayout(to:) for the rotation support
-    // It must be called in FloatingPanelController.traitCollectionDidChange(_:)
-    func updateHeight() {
-        guard let vc = vc else { return }
-        NSLayoutConstraint.deactivate(constraint: heightConstraint)
-        heightConstraint = nil
-
-        if layout is FloatingPanelIntrinsicLayout {
-            updateIntrinsicHeight()
-        }
-        defer {
-            if layout is FloatingPanelIntrinsicLayout {
-                NSLayoutConstraint.deactivate(fullConstraints)
-                fullConstraints = [
-                    surfaceView.topAnchor.constraint(equalTo: vc.layoutGuide.bottomAnchor,
-                                                     constant: -fullInset),
-                ]
-            }
-        }
-
-        guard vc.contentMode != .fitToBounds else { return }
-
-        switch layout {
-        case is FloatingPanelIntrinsicLayout:
-            heightConstraint = surfaceView.heightAnchor.constraint(equalToConstant: intrinsicHeight + safeAreaInsets.bottom)
-        default:
-            let const = -(positionY(for: topMostState))
-            heightConstraint =  surfaceView.heightAnchor.constraint(equalTo: vc.view.heightAnchor,
-                                                                    constant: const)
-        }
-        NSLayoutConstraint.activate(constraint: heightConstraint)
-
-        surfaceView.bottomOverflow = vc.view.bounds.height + layout.topInteractionBuffer
-    }
-
-    func updateInteractiveTopConstraint(diff: CGFloat, allowsTopBuffer: Bool, with behavior: FloatingPanelBehavior) {
-        defer {
-            layoutSurfaceIfNeeded() // MUST be called to update `surfaceView.frame`
-        }
-
-        let topMostConst: CGFloat = {
-            var ret: CGFloat = 0.0
-            switch layout.positionReference {
-            case .fromSafeArea:
-                ret = topY - safeAreaInsets.top
-            case .fromSuperview:
-                ret = topY
-            }
-            return ret
-        }()
-        let bottomMostConst: CGFloat = {
-            var ret: CGFloat = 0.0
-            let _bottomY = vc.isRemovalInteractionEnabled ? positionY(for: .hidden) : bottomY
-            switch layout.positionReference {
-            case .fromSafeArea:
-                ret = _bottomY - safeAreaInsets.top
-            case .fromSuperview:
-                ret = _bottomY
-            }
-            return ret
-        }()
-        let minConst = allowsTopBuffer ? topMostConst - layout.topInteractionBuffer : topMostConst
-        let maxConst = bottomMostConst + layout.bottomInteractionBuffer
-
-        var const = initialConst + diff
-
-        // Rubberbanding top buffer
-        if behavior.allowsRubberBanding(for: .top), const < topMostConst {
-            let buffer = topMostConst - const
-            const = topMostConst - rubberbandEffect(for: buffer, base: vc.view.bounds.height)
-        }
-
-        // Rubberbanding bottom buffer
-        if behavior.allowsRubberBanding(for: .bottom), const > bottomMostConst {
-            let buffer = const - bottomMostConst
-            const = bottomMostConst + rubberbandEffect(for: buffer, base: vc.view.bounds.height)
-        }
-
-        interactiveTopConstraint?.constant = max(minConst, min(maxConst, const))
-    }
-
-    // According to @chpwn's tweet: https://twitter.com/chpwn/status/285540192096497664
-    // x = distance from the edge
-    // c = constant value, UIScrollView uses 0.55
-    // d = dimension, either width or height
-    private func rubberbandEffect(for buffer: CGFloat, base: CGFloat) -> CGFloat {
-        return (1.0 - (1.0 / ((buffer * 0.55 / base) + 1.0))) * base
-    }
-
-    func activateFixedLayout() {
-        // Must deactivate `interactiveTopConstraint` here
-        NSLayoutConstraint.deactivate(constraint: self.interactiveTopConstraint)
-        self.interactiveTopConstraint = nil
-
-        NSLayoutConstraint.activate(fixedConstraints)
-
-        if vc.contentMode == .fitToBounds {
-            NSLayoutConstraint.activate(constraint: self.bottomConstraint)
-        }
-    }
-
-    func activateInteractiveLayout(of state: FloatingPanelPosition) {
-        defer {
-            layoutSurfaceIfNeeded()
-            log.debug("activateLayout -- surface.presentation = \(self.surfaceView.presentationFrame) surface.frame = \(self.surfaceView.frame)")
-        }
-
-        var state = state
-
-        setBackdropAlpha(of: state)
-
-        if validPositions.contains(state) == false {
-            state = layout.initialPosition
-        }
-
-        NSLayoutConstraint.deactivate(fullConstraints + halfConstraints + tipConstraints + offConstraints)
-        switch state {
-        case .full:
-            NSLayoutConstraint.activate(fullConstraints)
-        case .half:
-            NSLayoutConstraint.activate(halfConstraints)
-        case .tip:
-            NSLayoutConstraint.activate(tipConstraints)
-        case .hidden:
-            NSLayoutConstraint.activate(offConstraints)
-        }
-    }
-
-    func activateLayout(of state: FloatingPanelPosition) {
-        activateFixedLayout()
-        activateInteractiveLayout(of: state)
-    }
-
-    private func layoutSurfaceIfNeeded() {
-        #if !TEST
-        guard surfaceView.window != nil else { return }
-        #endif
-        surfaceView.superview?.layoutIfNeeded()
-    }
-
-    private func setBackdropAlpha(of target: FloatingPanelPosition) {
-        if target == .hidden {
-            self.backdropView.alpha = 0.0
-        } else {
-            self.backdropView.alpha = layout.backdropAlphaFor(position: target)
-        }
-    }
-
-    private func checkLayoutConsistance() {
-        // Verify layout configurations
-        assert(supportedPositions.count > 0)
-        assert(validPositions.contains(layout.initialPosition),
-               "Does not include an initial position (\(layout.initialPosition)) in (\(validPositions))")
-
-        if layout is FloatingPanelIntrinsicLayout {
-            assert(layout.insetFor(position: .full) == nil, "Return `nil` for full position on FloatingPanelIntrinsicLayout")
-        }
-
-        if halfInset > 0 {
-            assert(halfInset > tipInset, "Invalid half and tip insets")
-        }
-        // The verification isn't working on orientation change(portrait -> landscape)
-        // of a floating panel in tab bar. Because the `safeAreaInsets.bottom` is
-        // updated in delay so that it can be 83.0(not 53.0) even after the surface
-        // and the super view's frame is fit to landscape already.
-        /*if fullInset > 0 {
-            assert(middleY > topY, "Invalid insets { topY: \(topY), middleY: \(middleY) }")
-            assert(bottomY > topY, "Invalid insets { topY: \(topY), bottomY: \(bottomY) }")
-         }*/
-    }
-
-    func segument(at posY: CGFloat, forward: Bool) -> LayoutSegment {
-        /// ----------------------->Y
-        /// --> forward                <-- backward
-        /// |-------|===o===|-------|  |-------|-------|===o===|
-        /// |-------|-------x=======|  |-------|=======x-------|
-        /// |-------|-------|===o===|  |-------|===o===|-------|
-        /// pos: o/x, seguement: =
-        let sortedPositions = supportedPositions.sorted(by: { $0.rawValue < $1.rawValue })
-
-        let upperIndex: Int?
-        if forward {
-            #if swift(>=4.2)
-            upperIndex = sortedPositions.firstIndex(where: { posY < positionY(for: $0) })
-            #else
-            upperIndex = sortedPositions.index(where: { posY < positionY(for: $0) })
-            #endif
-        } else {
-            #if swift(>=4.2)
-            upperIndex = sortedPositions.firstIndex(where: { posY <= positionY(for: $0) })
-            #else
-            upperIndex = sortedPositions.index(where: { posY <= positionY(for: $0) })
-            #endif
-        }
-
-        switch upperIndex {
-        case 0:
-            return LayoutSegment(lower: nil, upper: sortedPositions.first)
-        case let upperIndex?:
-            return LayoutSegment(lower: sortedPositions[upperIndex - 1], upper: sortedPositions[upperIndex])
-        default:
-            return LayoutSegment(lower: sortedPositions[sortedPositions.endIndex - 1], upper: nil)
-        }
-    }
-}

Framework/Sources/FloatingPanelSurfaceView.swift

@@ -1,243 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2018/09/26.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
-
-import UIKit
-
-/// A view that presents a surface interface in a floating panel.
-public class FloatingPanelSurfaceView: UIView {
-
-    /// A GrabberHandleView object displayed at the top of the surface view.
-    ///
-    /// To use a custom grabber handle, hide this and then add the custom one
-    /// to the surface view at appropriate coordinates.
-    public let grabberHandle: GrabberHandleView = GrabberHandleView()
-
-    /// Offset of the grabber handle from the top
-    public var grabberTopPadding: CGFloat = 6.0 { didSet {
-        setNeedsUpdateConstraints()
-    } }
-
-    /// The height of the grabber bar area
-    public var topGrabberBarHeight: CGFloat {
-        return grabberTopPadding * 2 + grabberHandleHeight
-    }
-
-    /// Grabber view width and height
-    public var grabberHandleWidth: CGFloat = 36.0 { didSet {
-        setNeedsUpdateConstraints()
-    } }
-    public var grabberHandleHeight: CGFloat = 5.0 { didSet {
-        setNeedsUpdateConstraints()
-    } }
-
-    /// A root view of a content view controller
-    public weak var contentView: UIView!
-
-    /// The content insets specifying the insets around the content view.
-    public var contentInsets: UIEdgeInsets = .zero {
-        didSet {
-            // Needs update constraints
-            self.setNeedsUpdateConstraints()
-        }
-    }
-
-    private var color: UIColor? = .white { didSet { setNeedsLayout() } }
-    var bottomOverflow: CGFloat = 0.0 // Must not call setNeedsLayout()
-
-    public override var backgroundColor: UIColor? {
-        get { return color }
-        set { color = newValue }
-    }
-
-    /// The radius to use when drawing top rounded corners.
-    ///
-    /// `self.contentView` is masked with the top rounded corners automatically on iOS 11 and later.
-    /// On iOS 10, they are not automatically masked because of a UIVisualEffectView issue. See https://forums.developer.apple.com/thread/50854
-    public var cornerRadius: CGFloat {
-        set { containerView.layer.cornerRadius = newValue; setNeedsLayout() }
-        get { return containerView.layer.cornerRadius }
-    }
-
-    /// A Boolean indicating whether the surface shadow is displayed.
-    public var shadowHidden: Bool = false  { didSet { setNeedsLayout() } }
-
-    /// The color of the surface shadow.
-    public var shadowColor: UIColor = .black  { didSet { setNeedsLayout() } }
-
-    /// The offset (in points) of the surface shadow.
-    public var shadowOffset: CGSize = CGSize(width: 0.0, height: 1.0)  { didSet { setNeedsLayout() } }
-
-    /// The opacity of the surface shadow.
-    public var shadowOpacity: Float = 0.2 { didSet { setNeedsLayout() } }
-
-    /// The blur radius (in points) used to render the surface shadow.
-    public var shadowRadius: CGFloat = 3  { didSet { setNeedsLayout() } }
-
-    /// The width of the surface border.
-    public var borderColor: UIColor?  { didSet { setNeedsLayout() } }
-
-    /// The color of the surface border.
-    public var borderWidth: CGFloat = 0.0  { didSet { setNeedsLayout() } }
-
-    /// The margins to use when laying out the container view wrapping content.
-    public var containerMargins: UIEdgeInsets = .zero { didSet {
-        setNeedsUpdateConstraints()
-    } }
-
-    /// The view presents an actual surface shape.
-    ///
-    /// It renders the background color, border line and top rounded corners,
-    /// specified by other properties. The reason why they're not be applied to
-    /// a content view directly is because it avoids any side-effects to the
-    /// content view.
-    public let containerView: UIView = UIView()
-
-    @available(*, unavailable, renamed: "containerView")
-    public var backgroundView: UIView!
-
-    private lazy var containerViewTopConstraint = containerView.topAnchor.constraint(equalTo: topAnchor, constant: containerMargins.top)
-    private lazy var containerViewHeightConstraint = containerView.heightAnchor.constraint(equalTo: heightAnchor, multiplier: 1.0)
-    private lazy var containerViewLeftConstraint = containerView.leftAnchor.constraint(equalTo: leftAnchor, constant: 0.0)
-    private lazy var containerViewRightConstraint = containerView.rightAnchor.constraint(equalTo: rightAnchor, constant: 0.0)
-
-    /// The content view top constraint
-    private var contentViewTopConstraint: NSLayoutConstraint?
-    /// The content view left constraint
-    private var contentViewLeftConstraint: NSLayoutConstraint?
-    /// The content right constraint
-    private var contentViewRightConstraint: NSLayoutConstraint?
-    /// The content height constraint
-    private var contentViewHeightConstraint: NSLayoutConstraint?
-
-    private lazy var grabberHandleWidthConstraint = grabberHandle.widthAnchor.constraint(equalToConstant: grabberHandleWidth)
-    private lazy var grabberHandleHeightConstraint = grabberHandle.heightAnchor.constraint(equalToConstant: grabberHandleHeight)
-    private lazy var grabberHandleTopConstraint = grabberHandle.topAnchor.constraint(equalTo: topAnchor, constant: grabberTopPadding)
-
-    public override class var requiresConstraintBasedLayout: Bool { return true }
-
-    override init(frame: CGRect) {
-        super.init(frame: frame)
-        addSubViews()
-    }
-
-    required public init?(coder aDecoder: NSCoder) {
-        super.init(coder: aDecoder)
-        addSubViews()
-    }
-
-    private func addSubViews() {
-        super.backgroundColor = .clear
-        self.clipsToBounds = false
-
-        addSubview(containerView)
-        containerView.translatesAutoresizingMaskIntoConstraints = false
-        NSLayoutConstraint.activate([
-            containerViewTopConstraint,
-            containerViewLeftConstraint,
-            containerViewRightConstraint,
-            containerViewHeightConstraint,
-            ])
-
-        addSubview(grabberHandle)
-        grabberHandle.translatesAutoresizingMaskIntoConstraints = false
-        NSLayoutConstraint.activate([
-            grabberHandleWidthConstraint,
-            grabberHandleHeightConstraint,
-            grabberHandleTopConstraint,
-            grabberHandle.centerXAnchor.constraint(equalTo: centerXAnchor),
-            ])
-    }
-
-    public override func updateConstraints() {
-        containerViewTopConstraint.constant = containerMargins.top
-        containerViewLeftConstraint.constant = containerMargins.left
-        containerViewRightConstraint.constant = -containerMargins.right
-        containerViewHeightConstraint.constant = (containerMargins.bottom == 0) ? bottomOverflow : -(containerMargins.top + containerMargins.bottom)
-
-        contentViewTopConstraint?.constant = containerMargins.top + contentInsets.top
-        contentViewLeftConstraint?.constant = containerMargins.left + contentInsets.left
-        contentViewRightConstraint?.constant = containerMargins.right + contentInsets.right
-        contentViewHeightConstraint?.constant = -(containerMargins.top + containerMargins.bottom + contentInsets.top + contentInsets.bottom)
-
-        grabberHandleTopConstraint.constant = grabberTopPadding
-        grabberHandleWidthConstraint.constant = grabberHandleWidth
-        grabberHandleHeightConstraint.constant = grabberHandleHeight
-
-        super.updateConstraints()
-    }
-
-    public override func layoutSubviews() {
-        super.layoutSubviews()
-        log.debug("surface view frame = \(frame)")
-
-        containerView.backgroundColor = color
-
-        updateShadow()
-        updateCornerRadius()
-        updateBorder()
-    }
-
-    private func updateShadow() {
-        if shadowHidden == false {
-            if #available(iOS 11, *) {
-                // For clear background. See also, https://github.com/SCENEE/FloatingPanel/pull/51.
-                layer.shadowColor = shadowColor.cgColor
-                layer.shadowOffset = shadowOffset
-                layer.shadowOpacity = shadowOpacity
-                layer.shadowRadius = shadowRadius
-            } else {
-                // Can't update `layer.shadow*` directly because of a UIVisualEffectView issue in iOS 10, https://forums.developer.apple.com/thread/50854
-                // Instead, a user should display shadow appropriately.
-            }
-        }
-    }
-
-    private func updateCornerRadius() {
-        guard containerView.layer.cornerRadius != 0.0 else {
-            containerView.layer.masksToBounds = false
-            return
-        }
-        containerView.layer.masksToBounds = true
-        guard containerMargins.bottom == 0 else { return }
-        if #available(iOS 11, *) {
-            // Don't use `contentView.clipToBounds` because it prevents content view from expanding the height of a subview of it
-            // for the bottom overflow like Auto Layout settings of UIVisualEffectView in Main.storyboard of Example/Maps.
-            // Because the bottom of contentView must be fit to the bottom of a screen to work the `safeLayoutGuide` of a content VC.
-            containerView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
-        } else {
-            // Can't use `containerView.layer.mask` because of a UIVisualEffectView issue in iOS 10, https://forums.developer.apple.com/thread/50854
-            // Instead, a user should display rounding corners appropriately.
-        }
-    }
-
-    private func updateBorder() {
-        containerView.layer.borderColor = borderColor?.cgColor
-        containerView.layer.borderWidth = borderWidth
-    }
-
-    func add(contentView: UIView) {
-        containerView.addSubview(contentView)
-        self.contentView = contentView
-        /* contentView.frame = bounds */ // MUST NOT: Because the top safe area inset of a content VC will be incorrect.
-        contentView.translatesAutoresizingMaskIntoConstraints = false
-
-        let topConstraint = contentView.topAnchor.constraint(equalTo: topAnchor, constant: containerMargins.top + contentInsets.top)
-        let leftConstraint = contentView.leftAnchor.constraint(equalTo: leftAnchor, constant: containerMargins.left + contentInsets.left)
-        let rightConstraint = rightAnchor.constraint(equalTo: contentView.rightAnchor, constant: containerMargins.right + contentInsets.right)
-        let heightPadding = containerMargins.top + containerMargins.bottom + contentInsets.top + contentInsets.bottom
-        let heightConstraint = contentView.heightAnchor.constraint(equalTo: heightAnchor, constant: -heightPadding)
-        heightConstraint.priority = UILayoutPriority(999)
-        NSLayoutConstraint.activate([
-            topConstraint,
-            leftConstraint,
-            rightConstraint,
-            heightConstraint,
-            ])
-        self.contentViewTopConstraint = topConstraint
-        self.contentViewLeftConstraint = leftConstraint
-        self.contentViewRightConstraint = rightConstraint
-        self.contentViewHeightConstraint = heightConstraint
-    }
-}

Framework/Sources/UIExtensions.swift

@@ -1,158 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2018/09/18.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
-
-import UIKit
-
-protocol LayoutGuideProvider {
-    var topAnchor: NSLayoutYAxisAnchor { get }
-    var bottomAnchor: NSLayoutYAxisAnchor { get }
-}
-extension UILayoutGuide: LayoutGuideProvider {}
-
-class CustomLayoutGuide: LayoutGuideProvider {
-    let topAnchor: NSLayoutYAxisAnchor
-    let bottomAnchor: NSLayoutYAxisAnchor
-    init(topAnchor: NSLayoutYAxisAnchor, bottomAnchor: NSLayoutYAxisAnchor) {
-        self.topAnchor = topAnchor
-        self.bottomAnchor = bottomAnchor
-    }
-}
-
-extension UIViewController {
-    @objc var layoutInsets: UIEdgeInsets {
-        if #available(iOS 11.0, *) {
-            return view.safeAreaInsets
-        } else {
-            return UIEdgeInsets(top: topLayoutGuide.length,
-                                left: 0.0,
-                                bottom: bottomLayoutGuide.length,
-                                right: 0.0)
-        }
-    }
-
-    var layoutGuide: LayoutGuideProvider {
-        if #available(iOS 11.0, *) {
-            return view!.safeAreaLayoutGuide
-        } else {
-            return CustomLayoutGuide(topAnchor: topLayoutGuide.bottomAnchor,
-                                     bottomAnchor: bottomLayoutGuide.topAnchor)
-        }
-    }
-}
-
-protocol SideLayoutGuideProvider {
-    var leftAnchor: NSLayoutXAxisAnchor { get }
-    var rightAnchor: NSLayoutXAxisAnchor { get }
-}
-
-extension UIView: SideLayoutGuideProvider {}
-extension UILayoutGuide: SideLayoutGuideProvider {}
-
-// The reason why UIView has no extensions of safe area insets and top/bottom guides
-// is for iOS10 compat.
-extension UIView {
-    var sideLayoutGuide: SideLayoutGuideProvider {
-        if #available(iOS 11.0, *) {
-            return safeAreaLayoutGuide
-        } else {
-            return self
-        }
-    }
-
-    var presentationFrame: CGRect {
-        return layer.presentation()?.frame ?? frame
-    }
-}
-
-extension UIView {
-    func disableAutoLayout() {
-        let frame = self.frame
-        translatesAutoresizingMaskIntoConstraints = true
-        self.frame = frame
-    }
-    func enableAutoLayout() {
-        translatesAutoresizingMaskIntoConstraints = false
-    }
-
-    static func performWithLinear(startTime: Double = 0.0, relativeDuration: Double = 1.0, _ animations: @escaping (() -> Void)) {
-        UIView.animateKeyframes(withDuration: 0.0, delay: 0.0, options: [.calculationModeCubic], animations: {
-            UIView.addKeyframe(withRelativeStartTime: startTime, relativeDuration: relativeDuration, animations: animations)
-        }, completion: nil)
-    }
-}
-
-#if __FP_LOG
-#if swift(>=4.2)
-extension UIGestureRecognizer.State: CustomDebugStringConvertible {
-    public var debugDescription: String {
-        switch self {
-        case .began: return "began"
-        case .changed: return "changed"
-        case .failed: return "failed"
-        case .cancelled: return "cancelled"
-        case .ended: return "endeded"
-        case .possible: return "possible"
-        }
-    }
-}
-#else
-extension UIGestureRecognizerState: CustomDebugStringConvertible {
-    public var debugDescription: String {
-        switch self {
-        case .began: return "began"
-        case .changed: return "changed"
-        case .failed: return "failed"
-        case .cancelled: return "cancelled"
-        case .ended: return "endeded"
-        case .possible: return "possible"
-        }
-    }
-}
-#endif
-#endif
-
-extension UIScrollView {
-    var isLocked: Bool {
-        return !showsVerticalScrollIndicator && !bounces &&  isDirectionalLockEnabled
-    }
-}
-
-extension UISpringTimingParameters {
-    public convenience init(dampingRatio: CGFloat, frequencyResponse: CGFloat, initialVelocity: CGVector = .zero) {
-        let mass = 1 as CGFloat
-        let stiffness = pow(2 * .pi / frequencyResponse, 2) * mass
-        let damp = 4 * .pi * dampingRatio * mass / frequencyResponse
-        self.init(mass: mass, stiffness: stiffness, damping: damp, initialVelocity: initialVelocity)
-    }
-}
-
-extension CGPoint {
-    static var nan: CGPoint {
-        return CGPoint(x: CGFloat.nan, y: CGFloat.nan)
-    }
-    static func - (left: CGPoint, right: CGPoint) -> CGPoint {
-        return CGPoint(x: left.x - right.x, y: left.y - right.y)
-    }
-}
-
-extension UITraitCollection {
-    func shouldUpdateLayout(from previous: UITraitCollection) -> Bool {
-        return previous.horizontalSizeClass != horizontalSizeClass
-            || previous.verticalSizeClass != verticalSizeClass
-            || previous.preferredContentSizeCategory != preferredContentSizeCategory
-            || previous.layoutDirection != layoutDirection
-    }
-}
-
-extension NSLayoutConstraint {
-    static func activate(constraint: NSLayoutConstraint?) {
-        guard let constraint = constraint else { return }
-        self.activate([constraint])
-    }
-    static func deactivate(constraint: NSLayoutConstraint?) {
-        guard let constraint = constraint else { return }
-        self.deactivate([constraint])
-    }
-}

Framework/Tests/FloatingPanelControllerTests.swift

@@ -1,188 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2018/09/18.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
-
-import XCTest
-@testable import FloatingPanel
-
-class FloatingPanelControllerTests: XCTestCase {
-    override func setUp() {}
-    override func tearDown() {}
-
-    func test_warningRetainCycle() {
-        let myVC = MyZombieViewController(nibName: nil, bundle: nil)
-        let exp = expectation(description: "Warning retain cycle")
-        exp.expectedFulfillmentCount = 2 // For layout & behavior logs
-        log.hook = {(log, level) in
-            if log.contains("A memory leak will occur by a retain cycle because") {
-                XCTAssert(level == .warning)
-                exp.fulfill()
-            }
-        }
-        myVC.loadViewIfNeeded()
-        wait(for: [exp], timeout: 10)
-    }
-
-    func test_addPanel() {
-        guard let rootVC = UIApplication.shared.keyWindow?.rootViewController else { fatalError() }
-        let fpc = FloatingPanelController()
-        fpc.addPanel(toParent: rootVC)
-        XCTAssert(fpc.surfaceView.frame.minY ==  (fpc.view.bounds.height - fpc.layoutInsets.bottom) - fpc.layout.insetFor(position: .half)!)
-        fpc.move(to: .tip, animated: false)
-        XCTAssert(fpc.surfaceView.frame.minY == (fpc.view.bounds.height - fpc.layoutInsets.bottom) - fpc.layout.insetFor(position: .tip)!)
-    }
-
-    @available(iOS 12.0, *)
-    func test_updateLayout_willTransition() {
-        class MyDelegate: FloatingPanelControllerDelegate {
-            func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
-                if newCollection.userInterfaceStyle == .dark {
-                    XCTFail()
-                }
-                return nil
-            }
-        }
-        let myDelegate = MyDelegate()
-        let fpc = FloatingPanelController(delegate: myDelegate)
-        let traitCollection = UITraitCollection(traitsFrom: [fpc.traitCollection,
-                                                             UITraitCollection(userInterfaceStyle: .dark)])
-        XCTAssertEqual(traitCollection.userInterfaceStyle, .dark)
-        fpc.prepare(for: traitCollection)
-    }
-
-    func test_moveTo() {
-        let delegate = FloatingPanelTestDelegate()
-        let fpc = FloatingPanelController(delegate: delegate)
-        XCTAssertEqual(delegate.position, .hidden)
-        fpc.showForTest()
-        XCTAssertEqual(delegate.position, .half)
-
-        fpc.hide()
-        XCTAssertEqual(delegate.position, .hidden)
-        
-        fpc.move(to: .full, animated: false)
-        XCTAssertEqual(fpc.position, .full)
-        XCTAssertEqual(delegate.position, .full)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .full))
-
-        fpc.move(to: .half, animated: false)
-        XCTAssertEqual(fpc.position, .half)
-        XCTAssertEqual(delegate.position, .half)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .half))
-
-        fpc.move(to: .tip, animated: false)
-        XCTAssertEqual(fpc.position, .tip)
-        XCTAssertEqual(delegate.position, .tip)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .tip))
-
-        fpc.move(to: .hidden, animated: false)
-        XCTAssertEqual(fpc.position, .hidden)
-        XCTAssertEqual(delegate.position, .hidden)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .hidden))
-
-        fpc.move(to: .full, animated: true)
-        XCTAssertEqual(fpc.position, .full)
-        XCTAssertEqual(delegate.position, .full)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .full))
-
-        fpc.move(to: .half, animated: true)
-        XCTAssertEqual(fpc.position, .half)
-        XCTAssertEqual(delegate.position, .half)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .half))
-
-        fpc.move(to: .tip, animated: true)
-        XCTAssertEqual(fpc.position, .tip)
-        XCTAssertEqual(delegate.position, .tip)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .tip))
-
-        fpc.move(to: .hidden, animated: true)
-        XCTAssertEqual(fpc.position, .hidden)
-        XCTAssertEqual(delegate.position, .hidden)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .hidden))
-    }
-    
-    func test_moveWithNearbyPosition() {
-        let delegate = FloatingPanelTestDelegate()
-        let fpc = FloatingPanelController(delegate: delegate)
-        XCTAssertEqual(delegate.position, .hidden)
-        fpc.showForTest()
-        
-        XCTAssertEqual(fpc.nearbyPosition, .half)
-        
-        fpc.hide()
-        XCTAssertEqual(fpc.nearbyPosition, .tip)
-        
-        fpc.move(to: .full, animated: false)
-        XCTAssertEqual(fpc.nearbyPosition, .full)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .full))
-    }
-
-    func test_originSurfaceY() {
-        let fpc = FloatingPanelController(delegate: nil)
-        fpc.loadViewIfNeeded()
-        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
-        fpc.show(animated: false, completion: nil)
-
-        fpc.move(to: .full, animated: false)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .full))
-        fpc.move(to: .half, animated: false)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .half))
-        fpc.move(to: .tip, animated: false)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .tip))
-        fpc.move(to: .hidden, animated: false)
-        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.originYOfSurface(for: .hidden))
-    }
-
-    func test_contentMode() {
-        let fpc = FloatingPanelController(delegate: nil)
-        fpc.loadViewIfNeeded()
-        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
-        fpc.show(animated: false, completion: nil)
-
-        fpc.contentMode = .static
-
-        fpc.move(to: .full, animated: false)
-        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.originYOfSurface(for: .full))
-        fpc.move(to: .half, animated: false)
-        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.originYOfSurface(for: .full))
-        fpc.move(to: .tip, animated: false)
-        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.originYOfSurface(for: .full))
-
-        fpc.contentMode = .fitToBounds
-
-        fpc.move(to: .full, animated: false)
-        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.originYOfSurface(for: .full))
-        fpc.move(to: .half, animated: false)
-        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.originYOfSurface(for: .half))
-        fpc.move(to: .tip, animated: false)
-        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.originYOfSurface(for: .tip))
-    }
-}
-
-private class MyZombieViewController: UIViewController, FloatingPanelLayout, FloatingPanelBehavior, FloatingPanelControllerDelegate {
-    var fpc: FloatingPanelController?
-    override func viewDidLoad() {
-        fpc = FloatingPanelController(delegate: self)
-        fpc?.addPanel(toParent: self)
-    }
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
-        return self
-    }
-
-    func floatingPanel(_ vc: FloatingPanelController, behaviorFor newCollection: UITraitCollection) -> FloatingPanelBehavior? {
-        return self
-    }
-    var initialPosition: FloatingPanelPosition {
-        return .half
-    }
-
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return UIScreen.main.bounds.height == 667.0 ? 18.0 : 16.0
-        case .half: return 262.0
-        case .tip: return 69.0
-        case .hidden: return nil
-        }
-    }
-}

Framework/Tests/FloatingPanelLayoutTests.swift

@@ -1,291 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2019/06/27.
-//  Copyright © 2019 scenee. All rights reserved.
-//
-
-import XCTest
-@testable import FloatingPanel
-
-class FloatingPanelLayoutTests: XCTestCase {
-    var fpc: FloatingPanelController!
-    override func setUp() {
-        fpc = FloatingPanelController(delegate: nil)
-        fpc.loadViewIfNeeded()
-        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
-    }
-    override func tearDown() {}
-
-    func test_layoutAdapter_topAndBottomMostState() {
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.topMostState, .full)
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.bottomMostState, .tip)
-
-        class FloatingPanelLayoutWithHidden: FloatingPanelLayout {
-            func insetFor(position: FloatingPanelPosition) -> CGFloat? { return nil }
-            let initialPosition: FloatingPanelPosition = .hidden
-            let supportedPositions: Set<FloatingPanelPosition> = [.hidden, .half, .full]
-        }
-        class FloatingPanelLayout2Positions: FloatingPanelLayout {
-            func insetFor(position: FloatingPanelPosition) -> CGFloat? { return nil }
-            let initialPosition: FloatingPanelPosition = .tip
-            let supportedPositions: Set<FloatingPanelPosition> = [.tip, .half]
-        }
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayoutWithHidden()
-        fpc.delegate = delegate
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.topMostState, .full)
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.bottomMostState, .hidden)
-
-        delegate.layout = FloatingPanelLayout2Positions()
-        fpc.delegate = delegate
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.topMostState, .half)
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.bottomMostState, .tip)
-    }
-
-    func test_layoutSegment_3position() {
-        class FloatingPanelLayout3Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .half
-            let supportedPositions: Set<FloatingPanelPosition> = [.tip, .half, .full]
-        }
-
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout3Positions()
-        fpc.delegate = delegate
-
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let halfPos = fpc.originYOfSurface(for: .half)
-        let tipPos = fpc.originYOfSurface(for: .tip)
-
-        let minPos = CGFloat.leastNormalMagnitude
-        let maxPos = CGFloat.greatestFiniteMagnitude
-
-        assertLayoutSegment(fpc.floatingPanel, with: [
-            (#line, pos: minPos, forwardY: true, lower: nil, upper: .full),
-            (#line, pos: minPos, forwardY: false, lower: nil, upper: .full),
-            (#line, pos: fullPos, forwardY: true, lower: .full, upper: .half),
-            (#line, pos: fullPos, forwardY: false, lower: nil,  upper: .full),
-            (#line, pos: halfPos, forwardY: true, lower: .half, upper: .tip),
-            (#line, pos: halfPos, forwardY: false, lower: .full,  upper: .half),
-            (#line, pos: tipPos, forwardY: true, lower: .tip, upper: nil),
-            (#line, pos: tipPos, forwardY: false, lower: .half,  upper: .tip),
-            (#line, pos: maxPos, forwardY: true, lower: .tip, upper: nil),
-            (#line, pos: maxPos, forwardY: false, lower: .tip, upper: nil),
-            ])
-    }
-
-    func test_layoutSegment_2positions() {
-        class FloatingPanelLayout2Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .half
-            let supportedPositions: Set<FloatingPanelPosition> = [.half, .full]
-        }
-
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout2Positions()
-        fpc.delegate = delegate
-
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let halfPos = fpc.originYOfSurface(for: .half)
-
-        let minPos = CGFloat.leastNormalMagnitude
-        let maxPos = CGFloat.greatestFiniteMagnitude
-
-        assertLayoutSegment(fpc.floatingPanel, with: [
-            (#line, pos: minPos, forwardY: true, lower: nil, upper: .full),
-            (#line, pos: minPos, forwardY: false, lower: nil, upper: .full),
-            (#line, pos: fullPos, forwardY: true, lower: .full, upper: .half),
-            (#line, pos: fullPos, forwardY: false, lower: nil,  upper: .full),
-            (#line, pos: halfPos, forwardY: true, lower: .half, upper: nil),
-            (#line, pos: halfPos, forwardY: false, lower: .full,  upper: .half),
-            (#line, pos: maxPos, forwardY: true, lower: .half, upper: nil),
-            (#line, pos: maxPos, forwardY: false, lower: .half, upper: nil),
-            ])
-    }
-
-    func test_layoutSegment_1positions() {
-        class FloatingPanelLayout1Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .full
-            let supportedPositions: Set<FloatingPanelPosition> = [.full]
-        }
-
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout1Positions()
-        fpc.delegate = delegate
-
-        let fullPos = fpc.originYOfSurface(for: .full)
-
-        let minPos = CGFloat.leastNormalMagnitude
-        let maxPos = CGFloat.greatestFiniteMagnitude
-
-        assertLayoutSegment(fpc.floatingPanel, with: [
-            (#line, pos: minPos, forwardY: true, lower: nil, upper: .full),
-            (#line, pos: minPos, forwardY: false, lower: nil, upper: .full),
-            (#line, pos: fullPos, forwardY: true, lower: .full, upper: nil),
-            (#line, pos: fullPos, forwardY: false, lower: nil,  upper: .full),
-            (#line, pos: maxPos, forwardY: true, lower: .full, upper: nil),
-            (#line, pos: maxPos, forwardY: false, lower: .full, upper: nil),
-            ])
-    }
-
-    func test_updateInteractiveTopConstraint() {
-        fpc.showForTest()
-        fpc.move(to: .full, animated: false)
-
-        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.position)
-        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.position) // Should be ignore
-
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let tipPos = fpc.originYOfSurface(for: .tip)
-
-        var pre: CGFloat
-        var next: CGFloat
-        pre = fpc.surfaceView.frame.minY
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: -100.0, allowsTopBuffer: false, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, pre)
-
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: -100.0, allowsTopBuffer: true, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, fullPos - fpc.layout.topInteractionBuffer)
-
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: 100.0, allowsTopBuffer: true, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, fullPos + 100.0)
-
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: tipPos - fullPos, allowsTopBuffer: true, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, tipPos)
-
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: tipPos - fullPos + 100.0, allowsTopBuffer: true, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, tipPos + fpc.layout.bottomInteractionBuffer)
-
-        fpc.floatingPanel.layoutAdapter.endInteraction(at: fpc.position)
-    }
-
-    func test_updateInteractiveTopConstraintWithHidden() {
-        class FloatingPanelLayout2Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .hidden
-            let supportedPositions: Set<FloatingPanelPosition> = [.hidden, .full]
-        }
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout2Positions()
-        fpc.delegate = delegate
-        fpc.showForTest()
-        fpc.move(to: .full, animated: false)
-
-        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.position)
-
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let hiddenPos = fpc.originYOfSurface(for: .hidden)
-
-        var pre: CGFloat
-        var next: CGFloat
-        pre = fpc.surfaceView.frame.minY
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: -100.0, allowsTopBuffer: false, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, pre)
-
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: -100.0, allowsTopBuffer: true, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, fullPos - fpc.layout.topInteractionBuffer)
-
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: hiddenPos - fullPos + 100.0, allowsTopBuffer: true, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, hiddenPos + fpc.layout.bottomInteractionBuffer)
-
-        fpc.floatingPanel.layoutAdapter.endInteraction(at: fpc.position)
-    }
-
-    func test_updateInteractiveTopConstraintWithMinusInsets() {
-        class FloatingPanelLayoutMinusInsets: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .full
-            let supportedPositions: Set<FloatingPanelPosition> = [.tip, .full]
-            func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-                switch position {
-                case .full, .tip: return -200
-                default: return nil
-                }
-            }
-        }
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayoutMinusInsets()
-        fpc.delegate = delegate
-        fpc.showForTest()
-        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.position)
-
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let tipPos = fpc.originYOfSurface(for: .tip)
-        let current = fpc.surfaceView.frame.minY
-
-        var next: CGFloat
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: -100.0, allowsTopBuffer: false, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, current)
-
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: -100.0, allowsTopBuffer: true, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, fullPos - fpc.layout.topInteractionBuffer)
-
-        fpc.floatingPanel.layoutAdapter.updateInteractiveTopConstraint(diff: tipPos - fullPos + 100.0, allowsTopBuffer: true, with: fpc.behavior)
-        next = fpc.surfaceView.frame.minY
-        XCTAssertEqual(next, tipPos + fpc.layout.bottomInteractionBuffer)
-
-        fpc.floatingPanel.layoutAdapter.endInteraction(at: fpc.position)
-    }
-
-    func test_positionReference() {
-        fpc = CustomSafeAreaFloatingPanelController()
-        fpc.loadViewIfNeeded()
-        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
-
-        class MyFloatingPanelFullLayout: FloatingPanelTestLayout {
-            var initialPosition: FloatingPanelPosition = .half
-            var positionReference: FloatingPanelLayoutReference {
-                return .fromSuperview
-            }
-        }
-        class MyFloatingPanelSafeAreaLayout: FloatingPanelTestLayout {
-            var initialPosition: FloatingPanelPosition = .half
-            var positionReference: FloatingPanelLayoutReference {
-                return .fromSafeArea
-            }
-        }
-        let fullLayout = MyFloatingPanelFullLayout()
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = fullLayout
-        fpc.delegate = delegate
-        fpc.showForTest()
-
-        XCTAssertEqual(fpc.layout.positionReference, .fromSuperview)
-        XCTAssertEqual(fpc.originYOfSurface(for: .full), fullLayout.insetFor(position: .full))
-        XCTAssertEqual(fpc.originYOfSurface(for: .half), fpc.view!.frame.height - fullLayout.insetFor(position: .half)!)
-        XCTAssertEqual(fpc.originYOfSurface(for: .tip), fpc.view!.frame.height - fullLayout.insetFor(position: .tip)!)
-
-        let safeAreaLayout = MyFloatingPanelSafeAreaLayout()
-        delegate.layout = safeAreaLayout
-        fpc.delegate = delegate
-
-        XCTAssertEqual(fpc.layout.positionReference, .fromSafeArea)
-        XCTAssertEqual(fpc.originYOfSurface(for: .full),
-                       fullLayout.insetFor(position: .full)! + fpc.layoutInsets.top)
-        XCTAssertEqual(fpc.originYOfSurface(for: .half),
-                       fpc.view!.frame.height - (fullLayout.insetFor(position: .half)! +  fpc.layoutInsets.bottom))
-        XCTAssertEqual(fpc.originYOfSurface(for: .tip),
-                       fpc.view!.frame.height - (fullLayout.insetFor(position: .tip)! +  fpc.layoutInsets.bottom))
-    }
-}
-
-private typealias LayoutSegmentTestParameter = (UInt, pos: CGFloat, forwardY: Bool, lower: FloatingPanelPosition?, upper: FloatingPanelPosition?)
-private func assertLayoutSegment(_ floatingPanel: FloatingPanelCore, with params: [LayoutSegmentTestParameter]) {
-    params.forEach { (line, pos, forwardY, lowr, upper) in
-        let segument = floatingPanel.layoutAdapter.segument(at: pos, forward: forwardY)
-        XCTAssertEqual(segument.lower, lowr, line: line)
-        XCTAssertEqual(segument.upper, upper, line: line)
-    }
-}
-
-private class CustomSafeAreaFloatingPanelController: FloatingPanelController { }
-extension CustomSafeAreaFloatingPanelController {
-    override var layoutInsets: UIEdgeInsets {
-        return UIEdgeInsets(top: 64.0, left: 0.0, bottom: 0.0, right: 34.0)
-    }
-}

Framework/Tests/FloatingPanelPositionTests.swift

@@ -1,27 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2019/07/05.
-//  Copyright © 2019 scenee. All rights reserved.
-//
-
-import XCTest
-@testable import FloatingPanel
-
-class FloatingPanelPositionTests: XCTestCase {
-    override func setUp() { }
-    override func tearDown() { }
-
-    func test_nextAndPre() {
-        var positions: [FloatingPanelPosition]
-        positions = [.full, .half, .tip, .hidden]
-        XCTAssertEqual(FloatingPanelPosition.full.next(in: positions),  .half)
-        XCTAssertEqual(FloatingPanelPosition.full.pre(in: positions),  .full)
-        XCTAssertEqual(FloatingPanelPosition.hidden.next(in: positions), .hidden)
-        XCTAssertEqual(FloatingPanelPosition.hidden.pre(in: positions), .tip)
-
-        positions = [.full, .hidden]
-        XCTAssertEqual(FloatingPanelPosition.full.next(in: positions),  .hidden)
-        XCTAssertEqual(FloatingPanelPosition.full.pre(in: positions),  .full)
-        XCTAssertEqual(FloatingPanelPosition.hidden.next(in: positions), .hidden)
-        XCTAssertEqual(FloatingPanelPosition.hidden.pre(in: positions), .full)
-    }
-}

Framework/Tests/FloatingPanelSurfaceViewTests.swift

@@ -1,118 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2019/05/23.
-//  Copyright © 2019 Shin Yamamoto. All rights reserved.
-//
-
-import XCTest
-@testable import FloatingPanel
-
-class FloatingPanelSurfaceViewTests: XCTestCase {
-    override func setUp() {}
-    override func tearDown() {}
-
-    func test_surfaceView() {
-        let surface = FloatingPanelSurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
-        XCTAssertTrue(FloatingPanelSurfaceView.requiresConstraintBasedLayout)
-        XCTAssert(surface.contentView == nil)
-        surface.layoutIfNeeded()
-        XCTAssert(surface.grabberHandle.frame.minY == 6.0)
-        XCTAssert(surface.grabberHandle.frame.width == surface.grabberHandleWidth)
-        XCTAssert(surface.grabberHandle.frame.height == surface.grabberHandleHeight)
-        surface.backgroundColor = .red
-        surface.layoutIfNeeded()
-        XCTAssert(surface.backgroundColor == surface.containerView.backgroundColor)
-    }
-
-    func test_surfaceView_grabberHandle() {
-        let surface = FloatingPanelSurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
-        XCTAssert(surface.contentView == nil)
-        surface.layoutIfNeeded()
-        XCTAssert(surface.grabberHandle.frame.minY == 6.0)
-        XCTAssert(surface.grabberHandle.frame.width == surface.grabberHandleWidth)
-        XCTAssert(surface.grabberHandle.frame.height == surface.grabberHandleHeight)
-
-        surface.grabberHandleWidth = 44.0
-        surface.grabberHandleHeight = 12.0
-        surface.setNeedsLayout()
-        surface.layoutIfNeeded()
-        XCTAssert(surface.grabberHandle.frame.width == surface.grabberHandleWidth, "\(surface.grabberHandle.frame.width) == \(surface.grabberHandleWidth)")
-        XCTAssert(surface.grabberHandle.frame.height == surface.grabberHandleHeight, "\(surface.grabberHandle.frame.height) == \(surface.grabberHandleHeight)")
-    }
-
-    func test_surfaceView_containerMargins() {
-        let surface = FloatingPanelSurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
-        surface.layoutIfNeeded()
-        XCTAssertEqual(surface.containerView.frame, surface.bounds)
-        surface.containerMargins = UIEdgeInsets(top: 16.0, left: 16.0, bottom: 16.0, right: 16.0)
-        surface.setNeedsLayout()
-        surface.layoutIfNeeded()
-        XCTAssertEqual(surface.containerView.frame, surface.bounds.inset(by: surface.containerMargins))
-    }
-
-    func test_surfaceView_contentInsets() {
-        let surface = FloatingPanelSurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
-        let contentView = UIView()
-        surface.add(contentView: contentView)
-        surface.layoutIfNeeded()
-        XCTAssertEqual(surface.contentView.frame, surface.bounds)
-        surface.contentInsets = UIEdgeInsets(top: 16.0, left: 16.0, bottom: 16.0, right: 16.0)
-        surface.setNeedsLayout()
-        surface.layoutIfNeeded()
-        XCTAssertEqual(surface.contentView.frame, surface.bounds.inset(by: surface.contentInsets))
-    }
-
-    func test_surfaceView_containerMargins_and_contentInsets() {
-        let surface = FloatingPanelSurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
-        let contentView = UIView()
-        surface.add(contentView: contentView)
-        surface.layoutIfNeeded()
-        XCTAssertEqual(surface.contentView.frame, surface.bounds)
-        surface.containerMargins = UIEdgeInsets(top: 16.0, left: 16.0, bottom: 16.0, right: 16.0)
-        surface.contentInsets = UIEdgeInsets(top: 16.0, left: 16.0, bottom: 16.0, right: 16.0)
-        surface.setNeedsLayout()
-        surface.layoutIfNeeded()
-        XCTAssertEqual(surface.containerView.frame, surface.bounds.inset(by: surface.containerMargins))
-        XCTAssertEqual(surface.contentView.frame, surface.containerView.bounds.inset(by: surface.contentInsets))
-    }
-
-    func test_surfaceView_cornderRaduis() {
-        let surface = FloatingPanelSurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
-        XCTAssert(surface.cornerRadius == 0.0)
-        XCTAssert(surface.containerView.layer.masksToBounds == false)
-
-        surface.cornerRadius = 10.0
-        surface.layoutIfNeeded()
-        XCTAssert(surface.cornerRadius == 10.0)
-        XCTAssert(surface.containerView.layer.cornerRadius == 10.0)
-        XCTAssert(surface.containerView.layer.masksToBounds == true)
-
-        surface.containerView.layer.cornerRadius = 12.0
-        surface.layoutIfNeeded()
-        XCTAssert(surface.cornerRadius == 12.0)
-        XCTAssert(surface.containerView.layer.masksToBounds == true)
-
-        surface.cornerRadius = 0.0
-        surface.layoutIfNeeded()
-        XCTAssert(surface.cornerRadius == 0.0)
-        XCTAssert(surface.containerView.layer.cornerRadius == 0.0)
-        XCTAssert(surface.containerView.layer.masksToBounds == false)
-
-        surface.containerView.layer.cornerRadius = 12.0
-        surface.setNeedsLayout()
-        surface.layoutIfNeeded()
-        XCTAssert(surface.cornerRadius == 12.0)
-        XCTAssert(surface.containerView.layer.masksToBounds == true)
-    }
-
-    func test_surfaceView_border() {
-        let surface = FloatingPanelSurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
-        XCTAssert(surface.borderColor == nil)
-        XCTAssert(surface.borderWidth == 0.0)
-
-        surface.borderColor = .red
-        surface.borderWidth = 3.0
-        surface.layoutIfNeeded()
-        XCTAssert(surface.containerView.layer.borderColor == UIColor.red.cgColor)
-        XCTAssert(surface.containerView.layer.borderWidth == 3.0)
-    }
-}

Framework/Tests/Utils.swift

@@ -1,46 +0,0 @@
-//
-//  Created by Shin Yamamoto on 2019/06/27.
-//  Copyright © 2019 scenee. All rights reserved.
-//
-
-import Foundation
-@testable import FloatingPanel
-
-func waitRunLoop(secs: TimeInterval = 0) {
-    RunLoop.main.run(until: Date(timeIntervalSinceNow: secs))
-}
-
-extension FloatingPanelController {
-    func showForTest() {
-        loadViewIfNeeded()
-        view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
-        show(animated: false, completion: nil)
-    }
-}
-
-class FloatingPanelTestDelegate: FloatingPanelControllerDelegate {
-    var layout: FloatingPanelLayout?
-    var behavior: FloatingPanelBehavior?
-    var position: FloatingPanelPosition = .hidden
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
-        return layout
-    }
-    func floatingPanel(_ vc: FloatingPanelController, behaviorFor newCollection: UITraitCollection) -> FloatingPanelBehavior? {
-        return behavior
-    }
-    func floatingPanelDidChangePosition(_ vc: FloatingPanelController) {
-        position = vc.position
-    }
-}
-
-protocol FloatingPanelTestLayout: FloatingPanelFullScreenLayout {}
-extension FloatingPanelTestLayout {
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .full: return 20.0
-        case .half: return 250.0
-        case .tip: return 60.0
-        default: return nil
-        }
-    }
-}

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2018 Shin Yamamoto
+Copyright (c) 2018-Present Shin Yamamoto
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -18,4 +18,4 @@ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
+SOFTWARE.

Package.swift

@@ -21,7 +21,7 @@ let package = Package(
     targets: [
         // Targets are the basic building blocks of a package. A target can define a module or a test suite.
         // Targets can depend on other targets in this package, and on products in packages which this package depends on.
-        .target(name: "FloatingPanel", path: "Framework/Sources"),
+        .target(name: "FloatingPanel", path: "Sources"),
     ],
     swiftLanguageVersions: [.version("5")]
 )

README.md

@@ -2,10 +2,7 @@
 [![Version](https://img.shields.io/cocoapods/v/FloatingPanel.svg)](https://cocoapods.org/pods/FloatingPanel)
 [![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)
 [![Platform](https://img.shields.io/cocoapods/p/FloatingPanel.svg)](https://cocoapods.org/pods/FloatingPanel)
-[![Swift 4.1](https://img.shields.io/badge/Swift-4.1-orange.svg?style=flat)](https://swift.org/)
-[![Swift 4.2](https://img.shields.io/badge/Swift-4.2-orange.svg?style=flat)](https://swift.org/)
-[![Swift 5.0](https://img.shields.io/badge/Swift-5.0-orange.svg?style=flat)](https://swift.org/)
-[![Swift 5.1](https://img.shields.io/badge/Swift-5.1-orange.svg?style=flat)](https://swift.org/)
+[![Swift 5](https://img.shields.io/badge/Swift-5-orange.svg?style=flat)](https://swift.org/)
 
 # FloatingPanel
 
@@ -22,41 +19,45 @@ The new interface displays the related contents and utilities in parallel as a u
 - [Features](#features)
 - [Requirements](#requirements)
 - [Installation](#installation)
-  - [CocoaPods](#cocoapods)
-  - [Carthage](#carthage)
-  - [Swift Package Manager with Xcode 11](#swift-package-manager-with-xcode-11)
+    - [CocoaPods](#cocoapods)
+    - [Carthage](#carthage)
+    - [Swift Package Manager](#swift-package-manager)
 - [Getting Started](#getting-started)
-  - [Add a floating panel as a child view controller](#add-a-floating-panel-as-a-child-view-controller)
-  - [Present a floating panel as a modality](#present-a-floating-panel-as-a-modality)
+    - [Add a floating panel as a child view controller](#add-a-floating-panel-as-a-child-view-controller)
+    - [Present a floating panel as a modality](#present-a-floating-panel-as-a-modality)
 - [View hierarchy](#view-hierarchy)
 - [Usage](#usage)
-  - [Show/Hide a floating panel in a view with your view hierarchy](#showhide-a-floating-panel-in-a-view-with-your-view-hierarchy)
-  - [Scale the content view when the surface position changes](#scale-the-content-view-when-the-surface-position-changes)
-  - [Customize the layout with `FloatingPanelLayout` protocol](#customize-the-layout-with-floatingpanellayout-protocol)
-    - [Change the initial position and height](#change-the-initial-position-and-height)
-    - [Support your landscape layout](#support-your-landscape-layout)
-    - [Use Intrinsic height layout](#use-intrinsic-height-layout)
-    - [Specify position insets from the frame of `FloatingPanelController.view`, not the SafeArea](#specify-position-insets-from-the-frame-of-floatingpanelcontrollerview-not-the-safearea)
-  - [Customize the behavior with `FloatingPanelBehavior` protocol](#customize-the-behavior-with-floatingpanelbehavior-protocol)
-    - [Modify your floating panel's interaction](#modify-your-floating-panels-interaction)
-    - [Activate the rubber-band effect on the top/bottom edges](#activate-the-rubber-band-effect-on-the-topbottom-edges)
-    - [Manage the projection of a pan gesture momentum](#manage-the-projection-of-a-pan-gesture-momentum)
-  - [Customize the surface design](#customize-the-surface-design)
-    - [Use a custom grabber handle](#use-a-custom-grabber-handle)
-    - [Customize layout of the grabber handle](#customize-layout-of-the-grabber-handle)
-    - [Customize content padding from surface edges](#customize-content-padding-from-surface-edges)
-    - [Customize margins of the surface edges](#customize-margins-of-the-surface-edges)
-  - [Customize gestures](#customize-gestures)
-    - [Suppress the panel interaction](#suppress-the-panel-interaction)
-    - [Add tap gestures to the surface or backdrop views](#add-tap-gestures-to-the-surface-or-backdrop-views)
-  - [Create an additional floating panel for a detail](#create-an-additional-floating-panel-for-a-detail)
-  - [Move a position with an animation](#move-a-position-with-an-animation)
-  - [Work your contents together with a floating panel behavior](#work-your-contents-together-with-a-floating-panel-behavior)
+    - [Show/Hide a floating panel in a view with your view hierarchy](#showhide-a-floating-panel-in-a-view-with-your-view-hierarchy)
+    - [Scale the content view when the surface position changes](#scale-the-content-view-when-the-surface-position-changes)
+    - [Customize the layout with `FloatingPanelLayout` protocol](#customize-the-layout-with-floatingpanellayout-protocol)
+        - [Change the initial layout](#change-the-initial-layout)
+    - [Update your panel layout](#update-your-panel-layout)
+        - [Support your landscape layout](#support-your-landscape-layout)
+        - [Use the intrinsic size of a content in your panel layout](#use-the-intrinsic-size-of-a-content-in-your-panel-layout)
+        - [Specify an anchor for each state by an inset of the `FloatingPanelController.view` frame](#specify-an-anchor-for-each-state-by-an-inset-of-the-floatingpanelcontrollerview-frame)
+    - [Customize the behavior with `FloatingPanelBehavior` protocol](#customize-the-behavior-with-floatingpanelbehavior-protocol)
+        - [Modify your floating panel's interaction](#modify-your-floating-panels-interaction)
+        - [Activate the rubber-band effect on panel edges](#activate-the-rubber-band-effect-on-panel-edges)
+        - [Manage the projection of a pan gesture momentum](#manage-the-projection-of-a-pan-gesture-momentum)
+    - [Specify the panel move's boundary](#specify-the-panel-moves-boundary)
+    - [Customize the surface design](#customize-the-surface-design)
+        - [Modify your surface appearance](#modify-your-surface-appearance)
+        - [Use a custom grabber handle](#use-a-custom-grabber-handle)
+        - [Customize layout of the grabber handle](#customize-layout-of-the-grabber-handle)
+        - [Customize content padding from surface edges](#customize-content-padding-from-surface-edges)
+        - [Customize margins of the surface edges](#customize-margins-of-the-surface-edges)
+    - [Customize gestures](#customize-gestures)
+        - [Suppress the panel interaction](#suppress-the-panel-interaction)
+        - [Add tap gestures to the surface view](#add-tap-gestures-to-the-surface-view)
+        - [Interrupt the delegate methods of `FloatingPanelController.panGestureRecognizer`](#interrupt-the-delegate-methods-of-floatingpanelcontrollerpangesturerecognizer)
+    - [Create an additional floating panel for a detail](#create-an-additional-floating-panel-for-a-detail)
+    - [Move a position with an animation](#move-a-position-with-an-animation)
+    - [Work your contents together with a floating panel behavior](#work-your-contents-together-with-a-floating-panel-behavior)
 - [Notes](#notes)
-  - ['Show' or 'Show Detail' Segues from `FloatingPanelController`'s content view controller](#show-or-show-detail-segues-from-floatingpanelcontrollers-content-view-controller)
-  - [UISearchController issue](#uisearchcontroller-issue)
-  - [FloatingPanelSurfaceView's issue on iOS 10](#floatingpanelsurfaceviews-issue-on-ios-10)
-- [Author](#author)
+    - ['Show' or 'Show Detail' Segues from `FloatingPanelController`'s content view controller](#show-or-show-detail-segues-from-floatingpanelcontrollers-content-view-controller)
+    - [UISearchController issue](#uisearchcontroller-issue)
+    - [FloatingPanelSurfaceView's issue on iOS 10](#floatingpanelsurfaceviews-issue-on-ios-10)
+- [Maintainer](#maintainer)
 - [License](#license)
 
 <!-- /TOC -->
@@ -64,25 +65,32 @@ The new interface displays the related contents and utilities in parallel as a u
 ## Features
 
 - [x] Simple container view controller
-- [x] Fluid animation and gesture handling
+- [x] Fluid behavior using numeric springing
 - [x] Scroll view tracking
-- [x] Common UI elements: Grabber handle, Backdrop and Surface rounding corners
-- [x] 1~3 anchor positions(full, half, tip)
-- [x] Layout customization for all trait environments(i.e. Landscape orientation support)
-- [x] Behavior customization
-- [x] Free from common issues of Auto Layout and gesture handling
+- [x] Removal interaction
+- [x] Multi panel support
 - [x] Modal presentation
+- [x] 4 positioning support(top, left, bottom, right)
+- [x] 1~3 magnetic anchors(full, half, tip)
+- [x] Layout support for all trait environments(i.e. Landscape orientation)
+- [x] Common UI elements: surface, backdrop and grabber handle
+- [x] Free from common issues of Auto Layout and gesture handling
+- [x] Compatible with Objective-C
 
 Examples are here.
 
 - [Examples/Maps](https://github.com/SCENEE/FloatingPanel/tree/master/Examples/Maps) like Apple Maps.app.
 - [Examples/Stocks](https://github.com/SCENEE/FloatingPanel/tree/master/Examples/Stocks) like Apple Stocks.app.
+- [Examples/Samples](https://github.com/SCENEE/FloatingPanel/tree/master/Examples/Samples)
+- [Examples/SamplesObjC](https://github.com/SCENEE/FloatingPanel/tree/master/Examples/SamplesObjC)
 
 ## Requirements
 
-FloatingPanel is written in Swift 4.0+. It can be built by Xcode 9.4.1 or later. Compatible with iOS 10.0+.
+FloatingPanel is written in Swift 5.0+. Compatible with iOS 11.0+.
 
-✏️ The default Swift version is 4.0 because it avoids build errors with Carthage on each Xcode version from the source compatibility between Swift 4.0, 4.2 and 5.0.
+The deployment is still iOS 10, but it is recommended to use this library on iOS 11+.
+
+:pencil2: You would like to use Swift 4.0. Please use FloatingPanel v1. 
 
 ## Installation
 
@@ -95,7 +103,7 @@ it, simply add the following line to your Podfile:
 pod 'FloatingPanel'
 ```
 
-✏️FloatingPanel v1.7.0 or later requires CocoaPods v1.7.0+ for `swift_versions` support.
+:pencil2: FloatingPanel v1.7.0 or later requires CocoaPods v1.7.0+ for `swift_versions` support.
 
 ### Carthage
 
@@ -105,7 +113,7 @@ For [Carthage](https://github.com/Carthage/Carthage), add the following to your
 github "scenee/FloatingPanel"
 ```
 
-### Swift Package Manager with Xcode 11
+### Swift Package Manager
 
 Follow [this doc](https://developer.apple.com/documentation/swift_packages/adding_package_dependencies_to_your_app).
 
@@ -155,7 +163,7 @@ self.present(fpc, animated: true, completion: nil)
 
 You can show a floating panel over UINavigationController from the container view controllers as a modality of `.overCurrentContext` style.
 
-✏️ FloatingPanelController has the custom presentation controller. If you would like to customize the presentation/dismissal, please see [FloatingPanelTransitioning](https://github.com/SCENEE/FloatingPanel/blob/master/Framework/Sources/FloatingPanelTransitioning.swift).
+:pencil2: FloatingPanelController has the custom presentation controller. If you would like to customize the presentation/dismissal, please see [FloatingPanelTransitioning](https://github.com/SCENEE/FloatingPanel/blob/master/Framework/Sources/FloatingPanelTransitioning.swift).
 
 ## View hierarchy
 
@@ -167,7 +175,7 @@ FloatingPanelController.view (FloatingPanelPassThroughView)
  └─ .surfaceView (FloatingPanelSurfaceView)
     ├─ .containerView (UIView)
     │  └─ .contentView (FloatingPanelController.contentViewController.view)
-    └─ .grabberHandle (GrabberHandleView)
+    └─ .grabber (FloatingPanelGrabberView)
 ```
 
 ## Usage
@@ -239,33 +247,57 @@ fpc.contentMode = .fitToBounds
 
 Otherwise, `FloatingPanelController` fixes the content by the height of the top most position.
 
-✏️ In `.fitToBounds` mode, the surface height changes as following a user interaction so that you have a responsibility to configure Auto Layout constrains not to break the layout of a content view by the elastic surface height.
+:pencil2: In `.fitToBounds` mode, the surface height changes as following a user interaction so that you have a responsibility to configure Auto Layout constrains not to break the layout of a content view by the elastic surface height.
 
 ### Customize the layout with `FloatingPanelLayout` protocol
 
-#### Change the initial position and height
+#### Change the initial layout
 
 ```swift
 class ViewController: UIViewController, FloatingPanelControllerDelegate {
-    ...
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
-        return MyFloatingPanelLayout()
+    ... {
+        fpc = FloatingPanelController(delegate: self)
+        fpc.layout = MyFloatingPanelLayout()
     }
 }
 
 class MyFloatingPanelLayout: FloatingPanelLayout {
-    public var initialPosition: FloatingPanelPosition {
-        return .tip
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .tip
+    var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .bottom, referenceGuide: .safeArea),
+        ]
+    }
+}
+```
+
+### Update your panel layout
+
+There are 2 ways to update the panel layout.
+
+1. Manually set `FloatingPanelController.layout` to the new layout object directly.
+
+```swift
+fpc.layout = MyPanelLayout()
+fpc.invalidateLayout() // If needed
+```
+
+2. Returns an appropriate layout object in one of 2 `floatingPanel(_:layoutFor:)` delegates.
+
+```swift
+class ViewController: UIViewController, FloatingPanelControllerDelegate {
+    ...
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+        return MyFloatingPanelLayout()
     }
 
-    public func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-            case .full: return 16.0 // A top inset from safe area
-            case .half: return 216.0 // A bottom inset from the safe area
-            case .tip: return 44.0 // A bottom inset from the safe area
-            default: return nil // Or `case .hidden: return nil`
-        }
-    }
+    // OR
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor size: CGSize) -> FloatingPanelLayout {
+        return MyFloatingPanelLayout()
+    } 
 }
 ```
 
@@ -274,28 +306,21 @@ class MyFloatingPanelLayout: FloatingPanelLayout {
 ```swift
 class ViewController: UIViewController, FloatingPanelControllerDelegate {
     ...
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
-        return (newCollection.verticalSizeClass == .compact) ? FloatingPanelLandscapeLayout() : nil // Returning nil indicates to use the default layout
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+        return (newCollection.verticalSizeClass == .compact) ? LandscapePanelLayout() : FloatingPanelBottomLayout()
     }
 }
 
-class FloatingPanelLandscapeLayout: FloatingPanelLayout {
-    public var initialPosition: FloatingPanelPosition {
-        return .tip
+class LandscapePanelLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .tip
+    var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 69.0, edge: .bottom, referenceGuide: .safeArea),
+        ]
     }
-    public var supportedPositions: Set<FloatingPanelPosition> {
-        return [.full, .tip]
-    }
-
-    public func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-            case .full: return 16.0
-            case .tip: return 69.0
-            default: return nil
-        }
-    }
-
-    public func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
+    func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
         return [
             surfaceView.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 8.0),
             surfaceView.widthAnchor.constraint(equalToConstant: 291),
@@ -304,53 +329,46 @@ class FloatingPanelLandscapeLayout: FloatingPanelLayout {
 }
 ```
 
-#### Use Intrinsic height layout
+#### Use the intrinsic size of a content in your panel layout
 
 1. Lay out your content View with the intrinsic height size. For example, see "Detail View Controller scene"/"Intrinsic View Controller scene" of [Main.storyboard](https://github.com/SCENEE/FloatingPanel/blob/master/Examples/Samples/Sources/Base.lproj/Main.storyboard). The 'Stack View.bottom' constraint determines the intrinsic height.
-2. Create a layout that adopts and conforms to `FloatingPanelIntrinsicLayout` and use it.
+2. Specify layout anchors using `FloatingPanelIntrinsicLayoutAnchor`.
 
 ```swift
-class ViewController: UIViewController, FloatingPanelControllerDelegate {
-    ...
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
-        return RemovablePanelLayout()
-    }
-}
-
-class RemovablePanelLayout: FloatingPanelIntrinsicLayout {
-    var supportedPositions: Set<FloatingPanelPosition> {
-        return [.full, .half]
-    }
-    func insetFor(position: FloatingPanelPosition) -> CGFloat? {
-        switch position {
-        case .half: return 130.0
-        default: return nil  // Must return nil for .full
-        }
+class IntrinsicPanelLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .full
+    var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 0, referenceGuide: .safeArea),
+            .half: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.5, referenceGuide: .safeArea),
+        ]
     }
     ...
 }
 ```
 
-#### Specify position insets from the frame of `FloatingPanelController.view`, not the SafeArea
+:pencil2: `FloatingPanelIntrinsicLayout` is deprecated on v1.
 
-There are 2 ways. One is returning `.fromSuperview` for `FloatingPanelLayout.positionReference` in your layout.
+#### Specify an anchor for each state by an inset of the `FloatingPanelController.view` frame
+
+Use `.superview` reference guide in your anchors.
 
 ```swift
 class MyFullScreenLayout: FloatingPanelLayout {
     ...
-    var positionReference: FloatingPanelLayoutReference {
-        return .fromSuperview
+    var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .superview),
+            .half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .superview),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .bottom, referenceGuide: .superview),
+        ]
+
     }
 }
 ```
 
-Another is using `FloatingPanelFullScreenLayout` protocol.
-
-```swift
-class MyFullScreenLayout: FloatingPanelFullScreenLayout {
-    ...
-}
-```
+:pencil2: `FloatingPanelFullScreenLayout` is deprecated on v1.
 
 ### Customize the behavior with `FloatingPanelBehavior` protocol
 
@@ -359,25 +377,27 @@ class MyFullScreenLayout: FloatingPanelFullScreenLayout {
 ```swift
 class ViewController: UIViewController, FloatingPanelControllerDelegate {
     ...
-    func floatingPanel(_ vc: FloatingPanelController, behaviorFor newCollection: UITraitCollection) -> FloatingPanelBehavior? {
-        return FloatingPanelStocksBehavior()
+    func viewDidLoad() {
+        ...
+        fpc.behavior =  CustomPanelBehavior()
     }
 }
 
-class FloatingPanelStocksBehavior: FloatingPanelBehavior {
-    ...
-    func interactionAnimator(_ fpc: FloatingPanelController, to targetPosition: FloatingPanelPosition, with velocity: CGVector) -> UIViewPropertyAnimator {
-        let damping = self.damping(with: velocity)
-        let springTiming = UISpringTimingParameters(dampingRatio: damping, initialVelocity: velocity)
-        return UIViewPropertyAnimator(duration: 0.5, timingParameters: springTiming)
+class CustomPanelBehavior: FloatingPanelBehavior {
+    let springDecelerationRate = UIScrollView.DecelerationRate.fast.rawValue + 0.02
+    let springResponseTime = 0.4
+    func shouldProjectMomentum(_ fpc: FloatingPanelController, to proposedTargetPosition: FloatingPanelState) -> Bool {
+        return true
     }
 }
 ```
 
-#### Activate the rubber-band effect on the top/bottom edges
+:pencil2: `floatingPanel(_ vc:behaviorFor:)` is deprecated on v1.
+
+#### Activate the rubber-band effect on panel edges
 
 ```swift
-class FloatingPanelBehavior: FloatingPanelBehavior {
+class MyPanelBehavior: FloatingPanelBehavior {
     ...
     func allowsRubberBanding(for edge: UIRectEdge) -> Bool {
         return true
@@ -390,16 +410,56 @@ class FloatingPanelBehavior: FloatingPanelBehavior {
 This allows full projectional panel behavior. For example, a user can swipe up a panel from tip to full nearby the tip position.
 
 ```swift
-class FloatingPanelBehavior: FloatingPanelBehavior {
+class MyPanelBehavior: FloatingPanelBehavior {
     ...
-    func shouldProjectMomentum(_ fpc: FloatingPanelController, for proposedTargetPosition: FloatingPanelPosition) -> Bool {
+    func shouldProjectMomentum(_ fpc: FloatingPanelController, to proposedTargetPosition: FloatingPanelPosition) -> Bool {
         return true
     }
 }
 ```
 
+### Specify the panel move's boundary
+
+`FloatingPanelController.surfaceLocation` in `floatingPanelDidMove(_:)` delegate method behaves like `UIScrollView.contentOffset` in `scrollViewDidScroll(_:)`.
+As a result, you can specify the boundary of a panel move as below.
+
+```swift
+func floatingPanelDidMove(_ vc: FloatingPanelController) {
+    if vc.isAttracting == false {
+        let loc = vc.surfaceLocation
+        let minY = vc.surfaceLocation(for: .full).y - 6.0
+        let maxY = vc.surfaceLocation(for: .tip).y + 6.0
+        vc.surfaceLocation = CGPoint(x: loc.x, y: min(max(loc.y, minY), maxY))
+    }
+}
+```
+
+:pencil2: `{top,bottom}InteractionBuffer` property is removed from `FloatingPanelLayout` since v2.
+
 ### Customize the surface design
 
+#### Modify your surface appearance
+
+```swift
+// Create a new appearance.
+let appearance = SurfaceAppearance()
+
+// Define shadows
+let shadow = SurfaceAppearance.Shadow()
+shadow.color = UIColor.black
+shadow.offset = CGSize(width: 0, height: 16)
+shadow.radius = 16
+shadow.spread = 8
+appearance.shadows = [shadow]
+
+// Define corner radius and background color
+appearance.cornerRadius = 8.0
+appearance.backgroundColor = .clear
+
+// Set the new appearance
+fpc.surfaceView.appearance = appearance
+````
+
 #### Use a custom grabber handle
 
 ```swift
@@ -411,15 +471,16 @@ fpc.surfaceView.addSubview(myGrabberHandleView)
 #### Customize layout of the grabber handle
 
 ```swift
-fpc.surfaceView.grabberTopPadding = 10.0
-fpc.surfaceView.grabberHandleWidth = 44.0
-fpc.surfaceView.grabberHandleHeight = 12.0
+fpc.surfaceView.grabberHandlePadding = 10.0
+fpc.surfaceView.grabberHandleSize = .init(width: 44.0, height: 12.0)
 ```
 
+:pencil2: Note that `grabberHandleSize` width and height are reversed in the left/right position.
+
 #### Customize content padding from surface edges
 
 ```swift
-fpc.surfaceView.contentInsets = .init(top: 20, left: 20, bottom: 20, right: 20)
+fpc.surfaceView.contentPadding = .init(top: 20, left: 20, bottom: 20, right: 20)
 ```
 
 #### Customize margins of the surface edges
@@ -451,17 +512,13 @@ func floatingPanelShouldBeginDragging(_ vc: FloatingPanelController) -> Bool {
 }
 ```
 
-#### Add tap gestures to the surface or backdrop views
+#### Add tap gestures to the surface view
 
 ```swift
 override func viewDidLoad() {
     ...
-    surfaceTapGesture = UITapGestureRecognizer(target: self, action: #selector(handleSurface(tapGesture:)))
+    let surfaceTapGesture = UITapGestureRecognizer(target: self, action: #selector(handleSurface(tapGesture:)))
     fpc.surfaceView.addGestureRecognizer(surfaceTapGesture)
-
-    backdropTapGesture = UITapGestureRecognizer(target: self, action: #selector(handleBackdrop(tapGesture:)))
-    fpc.backdropView.addGestureRecognizer(backdropTapGesture)
-
     surfaceTapGesture.isEnabled = (fpc.position == .tip)
 }
 
@@ -471,6 +528,26 @@ func floatingPanelDidChangePosition(_ vc: FloatingPanelController) {
 }
 ```
 
+#### Interrupt the delegate methods of `FloatingPanelController.panGestureRecognizer`
+
+If you are set `FloatingPanelController.panGestureRecognizer.delegateProxy` to an object adopting `UIGestureRecognizerDelegate`, it overrides delegate methods of the pan gesture recognizer.
+
+```swift
+class MyGestureRecognizerDelegate: UIGestureRecognizerDelegate {
+    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+        return false
+    }
+}
+
+class ViewController: UIViewController {
+    let myGestureDelegate = MyGestureRecognizerDelegate()
+
+    func setUpFpc() {
+        ....
+        fpc.panGestureRecognizer.delegateProxy = myGestureDelegate
+    }
+```
+
 ### Create an additional floating panel for a detail
 
 ```swift
@@ -511,6 +588,14 @@ func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
 }
 ```
 
+You can also use a view animation to move a panel.
+
+```swift
+UIView.animate(withDuration: 0.25) {
+    self.fpc.move(to: .half, animated: false)
+}
+```
+
 ### Work your contents together with a floating panel behavior
 
 ```swift
@@ -523,8 +608,8 @@ class ViewController: UIViewController, FloatingPanelControllerDelegate {
         }
     }
 
-    func floatingPanelDidEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetPosition: FloatingPanelPosition) {
-        if targetPosition != .full {
+    func floatingPanelWillEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetState: UnsafeMutablePointer<FloatingPanelState>) {
+        if targetState.pointee != .full {
             searchVC.hideHeader()
         }
     }
@@ -586,7 +671,7 @@ override func viewDidLayoutSubviews() {
 ```
 * If you sets clear color to `FloatingPanelSurfaceView.backgroundColor`, please note the bottom overflow of your content on bouncing at full position. To prevent it, you need to expand your content. For example, See Example/Maps App's Auto Layout settings of `UIVisualEffectView` in Main.storyboard.
 
-## Author
+## Maintainer
 
 Shin Yamamoto <shin@scenee.com> | [@scenee](https://twitter.com/scenee)
 

Sources/BackdropView.swift

@@ -0,0 +1,11 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+
+/// A view that presents a backdrop interface behind a panel.
+@objc(FloatingPanelBackdropView)
+public class BackdropView: UIView {
+
+    /// The gesture recognizer for tap gestures to dismiss a panel.
+    public var dismissalTapGestureRecognizer: UITapGestureRecognizer!
+}

Sources/Behavior.swift

@@ -0,0 +1,125 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+
+/// An interface for generating behavior information to fine-tune the behavior of a panel.
+@objc
+public protocol FloatingPanelBehavior {
+    /// A floating-point value that determines the rate of oscillation magnitude reduction after the user lifts their finger.
+    ///
+    /// The oscillation magnitude to attract a panel to an anchor can be adjusted this value between 0.979 and 1.0
+    /// in increments of 0.001. When this value is around 0.979, the attraction uses a critically damped spring system.
+    /// When this value is between 0.978 and 1.0, it uses a underdamped spring system with a damping ratio computed by
+    /// this value. You shouldn't return less than 0.979 because the system is overdamped. If the pan gesture's velocity
+    /// is less than 300, this value is ignored and a panel applies a critically damped system.
+    @objc optional
+    var springDecelerationRate: CGFloat { get }
+
+    /// A floating-point value that determines the approximate time until a panel stops to an anchor after the user lifts their finger.
+    @objc optional
+    var springResponseTime: CGFloat { get }
+
+    /// Returns a deceleration rate to calculate a target position projected a dragging momentum.
+    ///
+    /// The default implementation of this method returns the normal deceleration rate of UIScrollView.
+    @objc optional
+    var momentumProjectionRate: CGFloat { get }
+
+    /// Asks the behavior if a panel should project a momentum of a user interaction to move the proposed position.
+    ///
+    /// The default implementation of this method returns true. This method is called for a layout to support all positions(tip, half and full).
+    /// Therefore, `proposedTargetPosition` can only be `FloatingPanelState.tip` or `FloatingPanelState.full`.
+    @objc optional
+    func shouldProjectMomentum(_ fpc: FloatingPanelController, to proposedTargetPosition: FloatingPanelState) -> Bool
+
+    /// Returns the progress to redirect to the previous position.
+    ///
+    /// The progress is represented by a floating-point value between 0.0 and 1.0, inclusive, where 1.0 indicates a panel is impossible to move to the next position. The default value is 0.5. Values less than 0.0 and greater than 1.0 are pinned to those limits.
+    @objc optional
+    func redirectionalProgress(_ fpc: FloatingPanelController, from: FloatingPanelState, to: FloatingPanelState) -> CGFloat
+
+    /// Asks the behavior whether the rubber band effect is enabled in moving over a given edge of the surface view.
+    ///
+    /// This method allows a panel to activate the rubber band effect to a given edge of the surface view. By default, the effect is disabled.
+    @objc optional
+    func allowsRubberBanding(for edge: UIRectEdge) -> Bool
+}
+
+/// The default behavior object for a panel
+///
+/// This behavior object is fine-tuned to behave as a search panel(card) in Apple Maps on iPhone portrait orientation.
+public class FloatingPanelDefaultBehavior: FloatingPanelBehavior {
+    public var springDecelerationRate: CGFloat {
+        return UIScrollView.DecelerationRate.fast.rawValue + 0.001
+    }
+
+    public var springResponseTime: CGFloat {
+        return 0.4
+    }
+
+    public var momentumProjectionRate: CGFloat {
+        return UIScrollView.DecelerationRate.normal.rawValue
+    }
+
+    public func redirectionalProgress(_ fpc: FloatingPanelController, from: FloatingPanelState, to: FloatingPanelState) -> CGFloat {
+        return 0.5
+    }
+
+    func addPanelAnimator(_ fpc: FloatingPanelController, to: FloatingPanelState) -> UIViewPropertyAnimator {
+        return UIViewPropertyAnimator(duration: 0.0,
+                                      timingParameters: UISpringTimingParameters(decelerationRate: UIScrollView.DecelerationRate.fast.rawValue,
+                                                                                 frequencyResponse: 0.25))
+    }
+
+    func removePanelAnimator(_ fpc: FloatingPanelController, from: FloatingPanelState, with velocity: CGVector) -> UIViewPropertyAnimator {
+        return UIViewPropertyAnimator(duration: 0.0,
+                                      timingParameters: UISpringTimingParameters(decelerationRate: UIScrollView.DecelerationRate.fast.rawValue,
+                                                                                 frequencyResponse: 0.25,
+                                                                                 initialVelocity: velocity))
+    }
+
+    public func allowsRubberBanding(for edge: UIRectEdge) -> Bool {
+        return false
+    }
+}
+
+class BehaviorAdapter {
+    unowned let vc: FloatingPanelController
+    fileprivate var behavior: FloatingPanelBehavior
+
+    init(vc: FloatingPanelController, behavior: FloatingPanelBehavior) {
+        self.vc = vc
+        self.behavior = behavior
+    }
+
+    var springDecelerationRate: CGFloat {
+        behavior.springDecelerationRate ?? FloatingPanelDefaultBehavior().springDecelerationRate
+    }
+
+    var springResponseTime: CGFloat {
+        behavior.springResponseTime ?? FloatingPanelDefaultBehavior().springResponseTime
+    }
+
+    var momentumProjectionRate: CGFloat {
+        behavior.momentumProjectionRate ?? FloatingPanelDefaultBehavior().momentumProjectionRate
+    }
+
+    func redirectionalProgress(from: FloatingPanelState, to: FloatingPanelState) -> CGFloat {
+        behavior.redirectionalProgress?(vc, from: from, to: to) ?? FloatingPanelDefaultBehavior().redirectionalProgress(vc,from: from, to: to)
+    }
+
+    func shouldProjectMomentum(to: FloatingPanelState) -> Bool {
+        behavior.shouldProjectMomentum?(vc, to: to) ?? false
+    }
+
+    func allowsRubberBanding(for edge: UIRectEdge) -> Bool {
+        behavior.allowsRubberBanding?(for: edge) ?? false
+    }
+}
+
+extension FloatingPanelController {
+    var _behavior: FloatingPanelBehavior {
+        get { floatingPanel.behaviorAdapter.behavior }
+        set { floatingPanel.behaviorAdapter.behavior = newValue}
+    }
+}

Sources/Controller.swift

@@ -1,134 +1,109 @@
-//
-//  Created by Shin Yamamoto on 2018/09/18.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
-public protocol FloatingPanelControllerDelegate: class {
-    // if it returns nil, FloatingPanelController uses the default layout
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout?
+/// A set of methods implemented by the delegate of a panel controller allows the adopting delegate to respond to
+/// messages from the FloatingPanelController class and thus respond to, and in some affect, operations such as
+/// dragging, attracting a panel, layout of a panel and the content, and transition animations.
+@objc public protocol FloatingPanelControllerDelegate: class {
+    /// Returns a FloatingPanelLayout object. If you use the default one, you can use a `FloatingPanelBottomLayout` object.
+    @objc(floatingPanel:layoutForTraitCollection:) optional
+    func floatingPanel(_ fpc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout
 
-    // if it returns nil, FloatingPanelController uses the default behavior
-    func floatingPanel(_ vc: FloatingPanelController, behaviorFor newCollection: UITraitCollection) -> FloatingPanelBehavior?
+    /// Returns a FloatingPanelLayout object. If you use the default one, you can use a `FloatingPanelBottomLayout` object.
+    @objc(floatingPanel:layoutForSize:) optional
+    func floatingPanel(_ fpc: FloatingPanelController, layoutFor size: CGSize) -> FloatingPanelLayout
 
-    /// Called when the floating panel has changed to a new position. Can be called inside an animation block, so any
-    /// view properties set inside this function will be automatically animated alongside the panel.
-    func floatingPanelDidChangePosition(_ vc: FloatingPanelController)
+    /// Returns a UIViewPropertyAnimator object to add/present the  panel to a position.
+    ///
+    /// Default is the spring animation with 0.25 secs.
+    @objc(floatingPanel:animatorForPresentingToState:) optional
+    func floatingPanel(_ fpc: FloatingPanelController, animatorForPresentingTo state: FloatingPanelState) -> UIViewPropertyAnimator
+
+    /// Returns a UIViewPropertyAnimator object to remove/dismiss a panel from a position.
+    ///
+    /// Default is the spring animator with 0.25 secs.
+    @objc(floatingPanel:animatorForDismissingWithVelocity:) optional
+    func floatingPanel(_ fpc: FloatingPanelController, animatorForDismissingWith velocity: CGVector) -> UIViewPropertyAnimator
+
+    /// Called when a panel has changed to a new position. Can be called inside an animation block, so any
+    /// view properties set inside this function will be automatically animated alongside a panel.
+    @objc optional
+    func floatingPanelDidChangePosition(_ fpc: FloatingPanelController)
 
     /// Asks the delegate if dragging should begin by the pan gesture recognizer.
-    func floatingPanelShouldBeginDragging(_ vc: FloatingPanelController) -> Bool
+    @objc optional
+    func floatingPanelShouldBeginDragging(_ fpc: FloatingPanelController) -> Bool
 
-    func floatingPanelDidMove(_ vc: FloatingPanelController) // any surface frame changes in dragging
+    /// Called when the user drags the surface or the surface is attracted to a state anchor.
+    @objc optional
+    func floatingPanelDidMove(_ fpc: FloatingPanelController) // any surface frame changes in dragging
 
-    // called on start of dragging (may require some time and or distance to move)
-    func floatingPanelWillBeginDragging(_ vc: FloatingPanelController)
-    // called on finger up if the user dragged. velocity is in points/second.
-    func floatingPanelDidEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetPosition: FloatingPanelPosition)
-    func floatingPanelWillBeginDecelerating(_ vc: FloatingPanelController) // called on finger up as we are moving
-    func floatingPanelDidEndDecelerating(_ vc: FloatingPanelController) // called when scroll view grinds to a halt
+    /// Called on start of dragging (may require some time and or distance to move)
+    @objc optional
+    func floatingPanelWillBeginDragging(_ fpc: FloatingPanelController)
 
-    // called on start of dragging to remove its views from a parent view controller
-    func floatingPanelDidEndDraggingToRemove(_ vc: FloatingPanelController, withVelocity velocity: CGPoint)
-    // called when its views are removed from a parent view controller
-    func floatingPanelDidEndRemove(_ vc: FloatingPanelController)
+    /// Called on finger up if the user dragged. velocity is in points/second.
+    @objc optional
+    func floatingPanelWillEndDragging(_ fpc: FloatingPanelController, withVelocity velocity: CGPoint, targetState: UnsafeMutablePointer<FloatingPanelState>)
 
-    /// Asks the delegate if the other gesture recognizer should be allowed to recognize the gesture in parallel.
+    /// Called on finger up if the user dragged.
     ///
-    /// By default, any tap and long gesture recognizers are allowed to recognize gestures simultaneously.
-    func floatingPanel(_ vc: FloatingPanelController, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool
+    /// If `attract` is true, it will continue moving afterwards to a nearby state anchor.
+    @objc optional
+    func floatingPanelDidEndDragging(_ fpc: FloatingPanelController, willAttract attract: Bool)
 
-    /// Asks the delegate for a content offset of the tracked scroll view to be pinned when a floating panel moves
+    /// Called when it is about to be attracted to a state anchor.
+    @objc optional
+    func floatingPanelWillBeginAttracting(_ fpc: FloatingPanelController, to state: FloatingPanelState) // called on finger up as a panel are moving
+
+    /// Called when attracting it is completed.
+    @objc optional
+    func floatingPanelDidEndAttracting(_ fpc: FloatingPanelController) // called when a panel stops
+
+    /// Asks the delegate whether a panel should be removed when dragging ended at the specified location
+    ///
+    /// This delegate method is called only where `FloatingPanelController.isRemovalInteractionEnabled` is `true`.
+    /// The velocity vector is calculated from the distance to a point of the hidden state and the pan gesture's velocity.
+    @objc(floatingPanel:shouldRemoveAtLocation:withVelocity:)
+    optional
+    func floatingPanel(_ fpc: FloatingPanelController, shouldRemoveAt location: CGPoint, with velocity: CGVector) -> Bool
+
+    /// Called on start to remove its view controller from the parent view controller.
+    @objc(floatingPanelWillRemove:)
+    optional
+    func floatingPanelWillRemove(_ fpc: FloatingPanelController)
+
+    /// Called when a panel is removed from the parent view controller.
+    @objc optional
+    func floatingPanelDidRemove(_ fpc: FloatingPanelController)
+
+    /// Asks the delegate for a content offset of the tracking scroll view to be pinned when a panel moves
     ///
     /// If you do not implement this method, the controller uses a value of the content offset plus the content insets
     /// of the tracked scroll view. Your implementation of this method can return a value for a navigation bar with a large
     /// title, for example.
     ///
     /// This method will not be called if the controller doesn't track any scroll view.
-    func floatingPanel(_ vc: FloatingPanelController, contentOffsetForPinning trackedScrollView: UIScrollView) -> CGPoint
-}
-
-public extension FloatingPanelControllerDelegate {
-    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout? {
-        return nil
-    }
-    func floatingPanel(_ vc: FloatingPanelController, behaviorFor newCollection: UITraitCollection) -> FloatingPanelBehavior? {
-        return nil
-    }
-    func floatingPanelDidChangePosition(_ vc: FloatingPanelController) {}
-    func floatingPanelShouldBeginDragging(_ vc: FloatingPanelController) -> Bool {
-        return true
-    }
-    func floatingPanelDidMove(_ vc: FloatingPanelController) {}
-    func floatingPanelWillBeginDragging(_ vc: FloatingPanelController) {}
-    func floatingPanelDidEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetPosition: FloatingPanelPosition) {}
-    func floatingPanelWillBeginDecelerating(_ vc: FloatingPanelController) {}
-    func floatingPanelDidEndDecelerating(_ vc: FloatingPanelController) {}
-
-    func floatingPanelDidEndDraggingToRemove(_ vc: FloatingPanelController, withVelocity velocity: CGPoint) {}
-    func floatingPanelDidEndRemove(_ vc: FloatingPanelController) {}
-
-    func floatingPanel(_ vc: FloatingPanelController, shouldRecognizeSimultaneouslyWith gestureRecognizer: UIGestureRecognizer) -> Bool {
-        return false
-    }
-    func floatingPanel(_ vc: FloatingPanelController, contentOffsetForPinning trackedScrollView: UIScrollView) -> CGPoint {
-        return CGPoint(x: 0.0, y: 0.0 - trackedScrollView.contentInset.top)
-    }
-}
-
-
-public enum FloatingPanelPosition: Int {
-    case full
-    case half
-    case tip
-    case hidden
-
-    static var allCases: [FloatingPanelPosition] {
-        return [.full, .half, .tip, .hidden]
-    }
-
-    func next(in positions: [FloatingPanelPosition]) -> FloatingPanelPosition {
-        #if swift(>=4.2)
-        guard
-            let index = positions.firstIndex(of: self),
-            positions.indices.contains(index + 1)
-            else { return self }
-        #else
-        guard
-            let index = positions.index(of: self),
-            positions.indices.contains(index + 1)
-            else { return self }
-        #endif
-        return positions[index + 1]
-    }
-
-    func pre(in positions: [FloatingPanelPosition]) -> FloatingPanelPosition {
-        #if swift(>=4.2)
-        guard
-            let index = positions.firstIndex(of: self),
-            positions.indices.contains(index - 1)
-            else { return self }
-        #else
-        guard
-            let index = positions.index(of: self),
-            positions.indices.contains(index - 1)
-            else { return self }
-        #endif
-        return positions[index - 1]
-    }
+    @objc(floatingPanel:contentOffsetForPinningScrollView:)
+    optional
+    func floatingPanel(_ fpc: FloatingPanelController, contentOffsetForPinning trackingScrollView: UIScrollView) -> CGPoint
 }
 
 ///
-/// A container view controller to display a floating panel to present contents in parallel as a user wants.
+/// A container view controller to display a panel to present contents in parallel as a user wants.
 ///
+@objc
 open class FloatingPanelController: UIViewController {
     /// Constants indicating how safe area insets are added to the adjusted content inset.
+    @objc
     public enum ContentInsetAdjustmentBehavior: Int {
         case always
         case never
     }
 
     /// A flag used to determine how the controller object lays out the content view when the surface position changes.
+    @objc
     public enum ContentMode: Int {
         /// The option to fix the content to keep the height of the top most position.
         case `static`
@@ -136,7 +111,8 @@ open class FloatingPanelController: UIViewController {
         case fitToBounds
     }
 
-    /// The delegate of the floating panel controller object.
+    /// The delegate of a panel controller object.
+    @objc 
     public weak var delegate: FloatingPanelControllerDelegate?{
         didSet{
             didUpdateDelegate()
@@ -144,41 +120,67 @@ open class FloatingPanelController: UIViewController {
     }
 
     /// Returns the surface view managed by the controller object. It's the same as `self.view`.
-    public var surfaceView: FloatingPanelSurfaceView! {
+    @objc
+    public var surfaceView: SurfaceView! {
         return floatingPanel.surfaceView
     }
 
     /// Returns the backdrop view managed by the controller object.
-    public var backdropView: FloatingPanelBackdropView! {
+    @objc
+    public var backdropView: BackdropView! {
         return floatingPanel.backdropView
     }
 
     /// Returns the scroll view that the controller tracks.
-    public weak var scrollView: UIScrollView? {
+    @objc
+    public weak var trackingScrollView: UIScrollView? {
         return floatingPanel.scrollView
     }
 
     // The underlying gesture recognizer for pan gestures
-    public var panGestureRecognizer: UIPanGestureRecognizer {
+    @objc
+    public var panGestureRecognizer: FloatingPanelPanGestureRecognizer {
         return floatingPanel.panGestureRecognizer
     }
 
-    /// The current position of the floating panel controller's contents.
-    public var position: FloatingPanelPosition {
+    /// The current position of a panel controller's contents.
+    @objc
+    public var state: FloatingPanelState {
         return floatingPanel.state
     }
 
+    /// A Boolean value indicating whether a panel controller is attracting the surface to a state anchor.
+    @objc
+    public var isAttracting: Bool {
+        return floatingPanel.isAttracting
+    }
+
     /// The layout object managed by the controller
+    @objc
     public var layout: FloatingPanelLayout {
-        return floatingPanel.layoutAdapter.layout
+        get { _layout }
+        set {
+            _layout = newValue
+            if let parent = parent, let layout = newValue as? UIViewController, layout == parent {
+                log.warning("A memory leak will occur by a retain cycle because \(self) owns the parent view controller(\(parent)) as the layout object. Don't let the parent adopt FloatingPanelLayout.")
+            }
+        }
     }
 
     /// The behavior object managed by the controller
+    @objc
     public var behavior: FloatingPanelBehavior {
-        return floatingPanel.behavior
+        get { _behavior }
+        set {
+            _behavior = newValue
+            if let parent = parent, let behavior = newValue as? UIViewController, behavior == parent {
+                log.warning("A memory leak will occur by a retain cycle because \(self) owns the parent view controller(\(parent)) as the behavior object. Don't let the parent adopt FloatingPanelBehavior.")
+            }
+        }
     }
 
     /// The content insets of the tracking scroll view derived from this safe area
+    @objc
     public var adjustedContentInsets: UIEdgeInsets {
         return floatingPanel.layoutAdapter.adjustedContentInsets
     }
@@ -186,46 +188,57 @@ open class FloatingPanelController: UIViewController {
     /// The behavior for determining the adjusted content offsets.
     ///
     /// This property specifies how the content area of the tracking scroll view is modified using `adjustedContentInsets`. The default value of this property is FloatingPanelController.ContentInsetAdjustmentBehavior.always.
+    @objc 
     public var contentInsetAdjustmentBehavior: ContentInsetAdjustmentBehavior = .always
 
     /// A Boolean value that determines whether the removal interaction is enabled.
+    @objc
     public var isRemovalInteractionEnabled: Bool {
-        set { floatingPanel.isRemovalInteractionEnabled = newValue }
-        get { return floatingPanel.isRemovalInteractionEnabled }
+        @objc(setRemovalInteractionEnabled:) set { floatingPanel.isRemovalInteractionEnabled = newValue }
+        @objc(isRemovalInteractionEnabled) get { return floatingPanel.isRemovalInteractionEnabled }
     }
 
-    /// The view controller responsible for the content portion of the floating panel.
+    /// The view controller responsible for the content portion of a panel.
+    @objc
     public var contentViewController: UIViewController? {
         set { set(contentViewController: newValue) }
         get { return _contentViewController }
     }
-    
-    /// The NearbyPosition determines that finger's nearby position.
-    public var nearbyPosition: FloatingPanelPosition {
-        let currentY = surfaceView.frame.minY
+
+    /// The NearbyState determines that finger's nearby state.
+    public var nearbyState: FloatingPanelState {
+        let currentY = surfaceLocation.y
         return floatingPanel.targetPosition(from: currentY, with: .zero)
     }
-    
+
+    /// Constants that define how a panel content fills in the surface.
+    @objc
     public var contentMode: ContentMode = .static {
         didSet {
-            guard position != .hidden else { return }
-            activateLayout()
+            guard state != .hidden else { return }
+            activateLayout(forceLayout: false)
         }
     }
 
     private var _contentViewController: UIViewController?
 
-    private(set) var floatingPanel: FloatingPanelCore!
+    private(set) var floatingPanel: Core!
     private var preSafeAreaInsets: UIEdgeInsets = .zero // Capture the latest one
     private var safeAreaInsetsObservation: NSKeyValueObservation?
-    private let modalTransition = FloatingPanelModalTransition()
+    private let modalTransition = ModalTransition()
 
     required public init?(coder aDecoder: NSCoder) {
         super.init(coder: aDecoder)
         setUp()
     }
 
-    /// Initialize a newly created floating panel controller.
+    override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?) {
+        super.init(nibName: nil, bundle: nil)
+        setUp()
+    }
+
+    /// Initialize a newly created panel controller.
+    @objc
     public init(delegate: FloatingPanelControllerDelegate? = nil) {
         super.init(nibName: nil, bundle: nil)
         self.delegate = delegate
@@ -238,14 +251,21 @@ open class FloatingPanelController: UIViewController {
         modalPresentationStyle = .custom
         transitioningDelegate = modalTransition
 
-        floatingPanel = FloatingPanelCore(self,
-                                      layout: fetchLayout(for: self.traitCollection),
-                                      behavior: fetchBehavior(for: self.traitCollection))
+        let initialLayout: FloatingPanelLayout
+        if let layout = delegate?.floatingPanel?(self, layoutFor: traitCollection) {
+            initialLayout = layout
+        } else {
+            initialLayout = FloatingPanelBottomLayout()
+        }
+        let initialBehavior = FloatingPanelDefaultBehavior()
+
+        floatingPanel = Core(self, layout: initialLayout, behavior: initialBehavior)
     }
 
     private func didUpdateDelegate(){
-        floatingPanel.layoutAdapter.layout = fetchLayout(for: traitCollection)
-        floatingPanel.behavior = fetchBehavior(for: self.traitCollection)
+        if let layout = delegate?.floatingPanel?(self, layoutFor: traitCollection) {
+            _layout = layout
+        }
     }
 
     // MARK:- Overrides
@@ -254,7 +274,7 @@ open class FloatingPanelController: UIViewController {
     open override func loadView() {
         assert(self.storyboard == nil, "Storyboard isn't supported")
 
-        let view = FloatingPanelPassThroughView()
+        let view = PassThroughView()
         view.backgroundColor = .clear
 
         backdropView.frame = view.bounds
@@ -268,12 +288,15 @@ open class FloatingPanelController: UIViewController {
 
     open override func viewDidLayoutSubviews() {
         super.viewDidLayoutSubviews()
-        if #available(iOS 11.0, *) {}
-        else {
+        if #available(iOS 11.0, *) {
+            // Ensure to update the static constraint of a panel after rotating a device in static mode
+            if contentMode == .static {
+                floatingPanel.layoutAdapter.updateStaticConstraint()
+            }
+        } else {
             // Because {top,bottom}LayoutGuide is managed as a view
-            if preSafeAreaInsets != layoutInsets,
-                floatingPanel.isDecelerating == false {
-                self.update(safeAreaInsets: layoutInsets)
+            if floatingPanel.isAttracting == false {
+                self.update(safeAreaInsets: fp_safeAreaInsets)
             }
         }
     }
@@ -281,6 +304,16 @@ open class FloatingPanelController: UIViewController {
     open override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
         super.viewWillTransition(to: size, with: coordinator)
 
+        if self.view.bounds.size == size {
+            return
+        }
+
+        // Change a layout for the new view size
+        if let newLayout = self.delegate?.floatingPanel?(self, layoutFor: size) {
+            layout = newLayout
+            activateLayout(forceLayout: false)
+        }
+
         if view.translatesAutoresizingMaskIntoConstraints {
             view.frame.size = size
             view.layoutIfNeeded()
@@ -289,7 +322,16 @@ open class FloatingPanelController: UIViewController {
 
     open override func willTransition(to newCollection: UITraitCollection, with coordinator: UIViewControllerTransitionCoordinator) {
         super.willTransition(to: newCollection, with: coordinator)
-        self.prepare(for: newCollection)
+
+        if shouldUpdateLayout(from: traitCollection, to: newCollection) == false {
+            return
+        }
+
+        // Change a layout for the new trait collection
+        if let newLayout = self.delegate?.floatingPanel?(self, layoutFor: newCollection) {
+            self.layout = newLayout
+            activateLayout(forceLayout: false)
+        }
     }
 
     open override func viewWillDisappear(_ animated: Bool) {
@@ -298,7 +340,6 @@ open class FloatingPanelController: UIViewController {
     }
 
     // MARK:- Child view controller to consult
-    #if swift(>=4.2)
     open override var childForStatusBarStyle: UIViewController? {
         return contentViewController
     }
@@ -314,46 +355,14 @@ open class FloatingPanelController: UIViewController {
     open override var childForHomeIndicatorAutoHidden: UIViewController? {
         return contentViewController
     }
-    #else
-    open override var childViewControllerForStatusBarStyle: UIViewController? {
-        return contentViewController
-    }
-
-    open override var childViewControllerForStatusBarHidden: UIViewController? {
-        return contentViewController
-    }
-
-    open override func childViewControllerForScreenEdgesDeferringSystemGestures() -> UIViewController? {
-        return contentViewController
-    }
-
-    open override func childViewControllerForHomeIndicatorAutoHidden() -> UIViewController? {
-        return contentViewController
-    }
-    #endif
-
-    // MARK:- Internals
-    func prepare(for newCollection: UITraitCollection) {
-        guard newCollection.shouldUpdateLayout(from: traitCollection) else { return }
-        // Change a layout & behavior for a new trait collection
-        reloadLayout(for: newCollection)
-        activateLayout()
-        floatingPanel.behavior = fetchBehavior(for: newCollection)
-    }
 
     // MARK:- Privates
 
-    private func fetchLayout(for traitCollection: UITraitCollection) -> FloatingPanelLayout {
-        switch traitCollection.verticalSizeClass {
-        case .compact:
-            return self.delegate?.floatingPanel(self, layoutFor: traitCollection) ?? FloatingPanelDefaultLandscapeLayout()
-        default:
-            return self.delegate?.floatingPanel(self, layoutFor: traitCollection) ?? FloatingPanelDefaultLayout()
-        }
-    }
-
-    private func fetchBehavior(for traitCollection: UITraitCollection) -> FloatingPanelBehavior {
-        return self.delegate?.floatingPanel(self, behaviorFor: traitCollection) ?? FloatingPanelDefaultBehavior()
+    private func shouldUpdateLayout(from previous: UITraitCollection, to new: UITraitCollection) -> Bool {
+        return previous.horizontalSizeClass != new.horizontalSizeClass
+            || previous.verticalSizeClass != new.verticalSizeClass
+            || previous.preferredContentSizeCategory != new.preferredContentSizeCategory
+            || previous.layoutDirection != new.layoutDirection
     }
 
     private func update(safeAreaInsets: UIEdgeInsets) {
@@ -366,53 +375,62 @@ open class FloatingPanelController: UIViewController {
         // Prevent an infinite loop on iOS 10: setUpLayout() -> viewDidLayoutSubviews() -> setUpLayout()
         preSafeAreaInsets = safeAreaInsets
 
-        activateLayout()
+        // preserve the current content offset if contentInsetAdjustmentBehavior is `.always`
+        var contentOffset: CGPoint?
+        if contentInsetAdjustmentBehavior == .always {
+            contentOffset = trackingScrollView?.contentOffset
+        }
+
+        floatingPanel.layoutAdapter.updateStaticConstraint()
+
+        if let contentOffset = contentOffset {
+            trackingScrollView?.contentOffset = contentOffset
+        }
 
         switch contentInsetAdjustmentBehavior {
         case .always:
-            scrollView?.contentInset = adjustedContentInsets
+            trackingScrollView?.contentInset = adjustedContentInsets
         default:
             break
         }
     }
 
-    private func reloadLayout(for traitCollection: UITraitCollection) {
-        floatingPanel.layoutAdapter.layout = fetchLayout(for: traitCollection)
-
-        if let parent = self.parent {
-            if let layout = layout as? UIViewController, layout == parent {
-                log.warning("A memory leak will occur by a retain cycle because \(self) owns the parent view controller(\(parent)) as the layout object. Don't let the parent adopt FloatingPanelLayout.")
-            }
-            if let behavior = behavior as? UIViewController, behavior == parent {
-                log.warning("A memory leak will occur by a retain cycle because \(self) owns the parent view controller(\(parent)) as the behavior object. Don't let the parent adopt FloatingPanelBehavior.")
-            }
-        }
-    }
-
-    private func activateLayout() {
-        floatingPanel.layoutAdapter.prepareLayout(in: self)
+    private func activateLayout(forceLayout: Bool = false) {
+        floatingPanel.layoutAdapter.prepareLayout()
 
         // preserve the current content offset if contentInsetAdjustmentBehavior is `.always`
         var contentOffset: CGPoint?
         if contentInsetAdjustmentBehavior == .always {
-            contentOffset = scrollView?.contentOffset
+            contentOffset = trackingScrollView?.contentOffset
         }
 
-        floatingPanel.layoutAdapter.updateHeight()
-        floatingPanel.layoutAdapter.activateLayout(of: floatingPanel.state)
+        floatingPanel.layoutAdapter.updateStaticConstraint()
+        floatingPanel.layoutAdapter.activateLayout(for: floatingPanel.state, forceLayout: forceLayout)
 
         if let contentOffset = contentOffset {
-            scrollView?.contentOffset = contentOffset
+            trackingScrollView?.contentOffset = contentOffset
+        }
+    }
+
+    func remove() {
+        if presentingViewController != nil, parent == nil {
+            delegate?.floatingPanelWillRemove?(self)
+            dismiss(animated: true) { [weak self] in
+                guard let self = self else { return }
+                self.delegate?.floatingPanelDidRemove?(self)
+            }
+        } else {
+            removePanelFromParent(animated: true)
         }
     }
 
     // MARK: - Container view controller interface
 
     /// Shows the surface view at the initial position defined by the current layout
+    @objc(show:completion:)
     public func show(animated: Bool = false, completion: (() -> Void)? = nil) {
         // Must apply the current layout here
-        reloadLayout(for: traitCollection)
-        activateLayout()
+        activateLayout(forceLayout: true)
 
         if #available(iOS 11.0, *) {
             // Must track the safeAreaInsets of `self.view` to update the layout.
@@ -422,9 +440,9 @@ open class FloatingPanelController: UIViewController {
             // 2. The safe area top inset can be variable on the large title navigation bar(iOS11+).
             // That's why it needs the observation to keep `adjustedContentInsets` correct.
             safeAreaInsetsObservation = self.view.observe(\.safeAreaInsets, options: [.initial, .new, .old]) { [weak self] (_, change) in
-                // Use `self.view.safeAreaInsets` becauese `change.newValue` can be nil in particular case when
+                // Use `self.view.safeAreaInsets` because `change.newValue` can be nil in particular case when
                 // is reported in https://github.com/SCENEE/FloatingPanel/issues/330
-                guard let `self` = self, change.oldValue != self.view.safeAreaInsets else { return }
+                guard let self = self, change.oldValue != self.view.safeAreaInsets else { return }
                 self.update(safeAreaInsets: self.view.safeAreaInsets)
             }
         } else {
@@ -432,12 +450,13 @@ open class FloatingPanelController: UIViewController {
             // Instead, update(safeAreaInsets:) is called at `viewDidLayoutSubviews()`
         }
 
-        move(to: floatingPanel.layoutAdapter.layout.initialPosition,
+        move(to: floatingPanel.layoutAdapter.initialState,
              animated: animated,
              completion: completion)
     }
 
     /// Hides the surface view to the hidden position
+    @objc(hide:completion:)
     public func hide(animated: Bool = false, completion: (() -> Void)? = nil) {
         move(to: .hidden,
              animated: animated,
@@ -447,30 +466,27 @@ open class FloatingPanelController: UIViewController {
     /// Adds the view managed by the controller as a child of the specified view controller.
     /// - Parameters:
     ///     - parent: A parent view controller object that displays FloatingPanelController's view. A container view controller object isn't applicable.
-    ///     - belowView: Insert the surface view managed by the controller below the specified view. By default, the surface view will be added to the end of the parent list of subviews.
+    ///     - viewIndex: Insert the surface view managed by the controller below the specified view index. By default, the surface view will be added to the end of the parent list of subviews.
     ///     - animated: Pass true to animate the presentation; otherwise, pass false.
-    public func addPanel(toParent parent: UIViewController, belowView: UIView? = nil, animated: Bool = false) {
+    @objc(addPanelToParent:at:animated:)
+    public func addPanel(toParent parent: UIViewController, at viewIndex: Int = -1, animated: Bool = false) {
         guard self.parent == nil else {
             log.warning("Already added to a parent(\(parent))")
             return
         }
-        precondition((parent is UINavigationController) == false, "UINavigationController displays only one child view controller at a time.")
-        precondition((parent is UITabBarController) == false, "UITabBarController displays child view controllers with a radio-style selection interface")
-        precondition((parent is UISplitViewController) == false, "UISplitViewController manages two child view controllers in a master-detail interface")
-        precondition((parent is UITableViewController) == false, "UITableViewController should not be the parent because the view is a table view so that a floating panel doens't work well")
-        precondition((parent is UICollectionViewController) == false, "UICollectionViewController should not be the parent because the view is a collection view so that a floating panel doens't work well")
+        assert((parent is UINavigationController) == false, "UINavigationController displays only one child view controller at a time.")
+        assert((parent is UITabBarController) == false, "UITabBarController displays child view controllers with a radio-style selection interface")
+        assert((parent is UISplitViewController) == false, "UISplitViewController manages two child view controllers in a master-detail interface")
+        assert((parent is UITableViewController) == false, "UITableViewController should not be the parent because the view is a table view so that a panel doesn't work well")
+        assert((parent is UICollectionViewController) == false, "UICollectionViewController should not be the parent because the view is a collection view so that a panel doesn't work well")
 
-        if let belowView = belowView {
-            parent.view.insertSubview(self.view, belowSubview: belowView)
-        } else {
+        if viewIndex < 0 {
             parent.view.addSubview(self.view)
+        } else {
+            parent.view.insertSubview(self.view, at: viewIndex)
         }
 
-        #if swift(>=4.2)
         parent.addChild(self)
-        #else
-        parent.addChildViewController(self)
-        #endif
 
         view.frame = parent.view.bounds // Needed for a correct safe area configuration
         view.translatesAutoresizingMaskIntoConstraints = false
@@ -483,11 +499,7 @@ open class FloatingPanelController: UIViewController {
 
         show(animated: animated) { [weak self] in
             guard let `self` = self else { return }
-            #if swift(>=4.2)
             self.didMove(toParent: parent)
-            #else
-            self.didMove(toParentViewController: parent)
-            #endif
         }
     }
 
@@ -495,28 +507,25 @@ open class FloatingPanelController: UIViewController {
     /// - Parameters:
     ///     - animated: Pass true to animate the presentation; otherwise, pass false.
     ///     - completion: The block to execute after the view controller is dismissed. This block has no return value and takes no parameters. You may specify nil for this parameter.
+    @objc(removePanelFromParent:completion:)
     public func removePanelFromParent(animated: Bool, completion: (() -> Void)? = nil) {
         guard self.parent != nil else {
             completion?()
             return
         }
 
+        delegate?.floatingPanelWillRemove?(self)
+
         hide(animated: animated) { [weak self] in
             guard let `self` = self else { return }
-            #if swift(>=4.2)
+
             self.willMove(toParent: nil)
-            #else
-            self.willMove(toParentViewController: nil)
-            #endif
 
             self.view.removeFromSuperview()
 
-            #if swift(>=4.2)
             self.removeFromParent()
-            #else
-            self.removeFromParentViewController()
-            #endif
 
+            self.delegate?.floatingPanelDidRemove?(self)
             completion?()
         }
     }
@@ -526,73 +535,42 @@ open class FloatingPanelController: UIViewController {
     ///     - to: Pass a FloatingPanelPosition value to move the surface view to the position.
     ///     - animated: Pass true to animate the presentation; otherwise, pass false.
     ///     - completion: The block to execute after the view controller has finished moving. This block has no return value and takes no parameters. You may specify nil for this parameter.
-    public func move(to: FloatingPanelPosition, animated: Bool, completion: (() -> Void)? = nil) {
-        precondition(floatingPanel.layoutAdapter.vc != nil, "Use show(animated:completion)")
+    @objc(moveToState:animated:completion:)
+    public func move(to: FloatingPanelState, animated: Bool, completion: (() -> Void)? = nil) {
+        assert(floatingPanel.layoutAdapter.vc != nil, "Use show(animated:completion)")
         floatingPanel.move(to: to, animated: animated, completion: completion)
     }
 
-    /// Sets the view controller responsible for the content portion of the floating panel.
+    /// Sets the view controller responsible for the content portion of a panel.
     public func set(contentViewController: UIViewController?) {
         if let vc = _contentViewController {
-            #if swift(>=4.2)
             vc.willMove(toParent: nil)
-            #else
-            vc.willMove(toParentViewController: nil)
-            #endif
-
             vc.view.removeFromSuperview()
-
-            #if swift(>=4.2)
             vc.removeFromParent()
-            #else
-            vc.removeFromParentViewController()
-            #endif
         }
 
         if let vc = contentViewController {
-            #if swift(>=4.2)
             addChild(vc)
-            #else
-            addChildViewController(vc)
-            #endif
 
             let surfaceView = floatingPanel.surfaceView
-            surfaceView.add(contentView: vc.view)
+            surfaceView.set(contentView: vc.view)
 
-            #if swift(>=4.2)
             vc.didMove(toParent: self)
-            #else
-            vc.didMove(toParentViewController: self)
-            #endif
         }
 
         _contentViewController = contentViewController
     }
 
-    @available(*, unavailable, renamed: "set(contentViewController:)")
-    open  override func show(_ vc: UIViewController, sender: Any?) {
-        if let target = self.parent?.targetViewController(forAction: #selector(UIViewController.show(_:sender:)), sender: sender) {
-            target.show(vc, sender: sender)
-        }
-    }
-
-    @available(*, unavailable, renamed: "set(contentViewController:)")
-    open  override func showDetailViewController(_ vc: UIViewController, sender: Any?) {
-        if let target = self.parent?.targetViewController(forAction: #selector(UIViewController.showDetailViewController(_:sender:)), sender: sender) {
-            target.showDetailViewController(vc, sender: sender)
-        }
-    }
-
     // MARK: - Scroll view tracking
 
     /// Tracks the specified scroll view to correspond with the scroll.
     ///
     /// - Parameters:
-    ///     - scrollView: Specify a scroll view to continuously and seamlessly work in concert with interactions of the surface view or nil to cancel it.
-    public func track(scrollView: UIScrollView?) {
-        guard let scrollView = scrollView else {
-            floatingPanel.scrollView = nil
-            return
+    ///     - scrollView: Specify a scroll view to continuously and seamlessly work in concert with interactions of the surface view
+    @objc(trackScrollView:)
+    public func track(scrollView: UIScrollView) {
+        if let scrollView = floatingPanel.scrollView {
+            untrack(scrollView: scrollView)
         }
 
         floatingPanel.scrollView = scrollView
@@ -602,21 +580,24 @@ open class FloatingPanelController: UIViewController {
             if #available(iOS 11.0, *) {
                 scrollView.contentInsetAdjustmentBehavior = .never
             } else {
-                #if swift(>=4.2)
                 children.forEach { (vc) in
                     vc.automaticallyAdjustsScrollViewInsets = false
                 }
-                #else
-                childViewControllers.forEach { (vc) in
-                    vc.automaticallyAdjustsScrollViewInsets = false
-                }
-                #endif
             }
         default:
             break
         }
     }
 
+    /// Cancel tracking the specify scroll view.
+    ///
+    @objc(untrackScrollView:)
+    public func untrack(scrollView: UIScrollView) {
+        if floatingPanel.scrollView == scrollView {
+            floatingPanel.scrollView = nil
+        }
+    }
+
     // MARK: - Utilities
 
     /// Updates the layout object from the delegate and lays out the views managed
@@ -624,16 +605,41 @@ open class FloatingPanelController: UIViewController {
     ///
     /// This method updates the `FloatingPanelLayout` object from the delegate and
     /// then it calls `layoutIfNeeded()` of the root view to force the view
-    /// to update the floating panel's layout immediately. It can be called in an
+    /// to update the layout immediately. It can be called in an
     /// animation block.
-    public func updateLayout() {
-        reloadLayout(for: traitCollection)
-        activateLayout()
+    @objc
+    public func invalidateLayout() {
+        activateLayout(forceLayout: true)
     }
 
-    /// Returns the y-coordinate of the point at the origin of the surface view.
-    public func originYOfSurface(for pos: FloatingPanelPosition) -> CGFloat {
-        return floatingPanel.layoutAdapter.positionY(for: pos)
+    /// Returns the surface's position in a panel controller's view for the specified state.
+    ///
+    /// If a panel is top positioned, this returns a point of the bottom-left corner of the surface. If it is left positioned
+    /// this returns a point of top-right corner of the surface. If it is bottom or right positioned, this returns a point
+    /// of the top-left corner of the surface.
+    @objc
+    public func surfaceLocation(for state: FloatingPanelState) -> CGPoint {
+        return floatingPanel.layoutAdapter.surfaceLocation(for: state)
+    }
+
+    /// The surface's position in a panel controller's view.
+    ///
+    /// If a panel is top positioned, this returns a point of the bottom-left corner of the surface. If it is left positioned
+    /// this returns a point of top-right corner of the surface. If it is bottom or right positioned, this returns a point
+    /// of the top-left corner of the surface.
+    @objc
+    public var surfaceLocation: CGPoint {
+        get { floatingPanel.layoutAdapter.surfaceLocation }
+        set { floatingPanel.layoutAdapter.surfaceLocation = newValue }
+    }
+}
+
+extension FloatingPanelController {
+    func notifyDidMove() {
+        #if !TEST
+        guard self.view.window != nil else { return }
+        #endif
+        delegate?.floatingPanelDidMove?(self)
     }
 }
 

Sources/FloatingPanel.h

@@ -0,0 +1,11 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+#ifndef FloatingPanel_h
+#define FloatingPanel_h
+
+#import <UIKit/UIKit.h>
+
+FOUNDATION_EXPORT double FloatingPanelVersionNumber;
+FOUNDATION_EXPORT const unsigned char FloatingPanelVersionString[];
+
+#endif /* FloatingPanel_h */

Sources/GrabberView.swift

@@ -1,11 +1,10 @@
-//
-//  Created by Shin Yamamoto on 2018/09/19.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
-public class GrabberHandleView: UIView {
+/// A view that presents a grabber handle in the surface of a panel.
+@objc(FloatingPanelGrabberView)
+public class GrabberView: UIView {
 
     public var barColor = UIColor(displayP3Red: 0.76, green: 0.77, blue: 0.76, alpha: 1.0) { didSet { backgroundColor = barColor } }
 
@@ -30,6 +29,5 @@ public class GrabberHandleView: UIView {
 
     private func render() {
         self.layer.masksToBounds = true
-        self.layer.cornerRadius = frame.size.height * 0.5
     }
 }

Sources/Info.plist

@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>1.7.6</string>
+	<string>2.0.1</string>
 	<key>CFBundleVersion</key>
 	<string>$(CURRENT_PROJECT_VERSION)</string>
 </dict>

Sources/Layout.swift

@@ -0,0 +1,829 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+
+/// An interface for generating layout information for a panel.
+@objc public protocol FloatingPanelLayout {
+    /// Returns the position of a panel in a `FloatingPanelController` view .
+    @objc var position: FloatingPanelPosition { get }
+
+    /// Returns the initial state when a panel is presented.
+    @objc var initialState: FloatingPanelState { get }
+
+    /// Returns the layout anchors to specify the snapping locations for each state.
+    @objc var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] { get }
+
+    /// Returns layout constraints to determine the cross dimension of a panel.
+    @objc optional func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint]
+
+    /// Returns the alpha value of the backdrop of a panel for each state.
+    @objc optional func backdropAlpha(for state: FloatingPanelState) -> CGFloat
+}
+
+/// A layout object that lays out a panel in bottom sheet style.
+@objcMembers
+open class FloatingPanelBottomLayout: NSObject, FloatingPanelLayout {
+    public override init() {
+        super.init()
+    }
+    open var initialState: FloatingPanelState {
+        return .half
+    }
+
+    open var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring]  {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 18.0, edge: .top, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 69.0, edge: .bottom, referenceGuide: .safeArea),
+        ]
+    }
+
+    open var position: FloatingPanelPosition {
+        return .bottom
+    }
+
+    open func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
+        return [
+            surfaceView.leftAnchor.constraint(equalTo: view.fp_safeAreaLayoutGuide.leftAnchor, constant: 0.0),
+            surfaceView.rightAnchor.constraint(equalTo: view.fp_safeAreaLayoutGuide.rightAnchor, constant: 0.0),
+        ]
+    }
+
+    open func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return state == .full ? 0.3 : 0.0
+    }
+}
+
+struct LayoutSegment {
+    let lower: FloatingPanelState?
+    let upper: FloatingPanelState?
+}
+
+class LayoutAdapter {
+    weak var vc: FloatingPanelController!
+    private weak var surfaceView: SurfaceView!
+    private weak var backdropView: BackdropView!
+    private let defaultLayout = FloatingPanelBottomLayout()
+
+    fileprivate var layout: FloatingPanelLayout {
+        didSet {
+            surfaceView.position = position
+        }
+    }
+
+    private var safeAreaInsets: UIEdgeInsets {
+        return vc?.fp_safeAreaInsets ?? .zero
+    }
+
+    private var initialConst: CGFloat = 0.0
+
+    private var fixedConstraints: [NSLayoutConstraint] = []
+    private var fullConstraints: [NSLayoutConstraint] = []
+    private var halfConstraints: [NSLayoutConstraint] = []
+    private var tipConstraints: [NSLayoutConstraint] = []
+    private var offConstraints: [NSLayoutConstraint] = []
+    private var fitToBoundsConstraint: NSLayoutConstraint?
+
+    private(set) var interactionConstraint: NSLayoutConstraint?
+    private(set) var attractionConstraint: NSLayoutConstraint?
+
+    private var staticConstraint: NSLayoutConstraint?
+
+    private var activeStates: Set<FloatingPanelState> {
+        return Set(layout.anchors.keys)
+    }
+
+    var initialState: FloatingPanelState {
+        layout.initialState
+    }
+
+    var position: FloatingPanelPosition {
+        layout.position
+    }
+
+    var orderedStates: [FloatingPanelState] {
+        return activeStates.sorted(by: {
+            return $0.order < $1.order
+        })
+    }
+
+    var validStates: Set<FloatingPanelState> {
+        return activeStates.union([.hidden])
+    }
+
+    var sortedDirectionalStates: [FloatingPanelState] {
+        return activeStates.sorted(by: {
+            switch position {
+            case .top, .left:
+                return $0.order < $1.order
+            case .bottom, .right:
+                return $0.order > $1.order
+            }
+        })
+    }
+
+    private var directionalLeastState: FloatingPanelState {
+        return sortedDirectionalStates.first ?? .hidden
+    }
+
+    private var directionalMostState: FloatingPanelState {
+        return sortedDirectionalStates.last ?? .hidden
+    }
+
+    var edgeLeastState: FloatingPanelState {
+        if orderedStates.count == 1 {
+            return .hidden
+        }
+        return orderedStates.first ?? .hidden
+    }
+
+    var edgeMostState: FloatingPanelState {
+        if orderedStates.count == 1 {
+            return orderedStates[0]
+        }
+        return orderedStates.last ?? .hidden
+    }
+
+    var edgeMostY: CGFloat {
+        return position(for: edgeMostState)
+    }
+
+    var adjustedContentInsets: UIEdgeInsets {
+        switch position {
+        case .top:
+            return UIEdgeInsets(top: safeAreaInsets.top,
+                                left: 0.0,
+                                bottom: 0.0,
+                                right: 0.0)
+        case .left:
+            return UIEdgeInsets(top: 0.0,
+                                left: safeAreaInsets.left,
+                                bottom: 0.0,
+                                right: 0.0)
+        case .bottom:
+            return UIEdgeInsets(top: 0.0,
+                                left: 0.0,
+                                bottom: safeAreaInsets.bottom,
+                                right: 0.0)
+        case .right:
+            return UIEdgeInsets(top: 0.0,
+                                left: 0.0,
+                                bottom: 0.0,
+                                right: safeAreaInsets.right)
+        }
+    }
+
+    /*
+    Returns a constraint based value in the interaction and animation.
+
+    So that it doesn't need to call `surfaceView.layoutIfNeeded()`
+    after every interaction and animation update. It has an effect on
+    the smooth interaction because the content view doesn't need to update
+    its layout frequently.
+    */
+    var surfaceLocation: CGPoint {
+        get {
+            var pos: CGFloat
+            if let constraint = interactionConstraint {
+                pos = constraint.constant
+            } else if let animationConstraint = attractionConstraint, let anchor = layout.anchors[vc.state] {
+                switch position {
+                case .top, .bottom:
+                    switch referenceEdge(of: anchor) {
+                    case .top:
+                        pos = animationConstraint.constant
+                        if anchor.referenceGuide == .safeArea {
+                            pos += safeAreaInsets.top
+                        }
+                    case .bottom:
+                        pos = vc.view.bounds.height + animationConstraint.constant
+                        if anchor.referenceGuide == .safeArea {
+                            pos -= safeAreaInsets.bottom
+                        }
+                    default:
+                        fatalError("Unsupported reference edges")
+                    }
+                case .left, .right:
+                    switch referenceEdge(of: anchor) {
+                    case .left:
+                        pos = animationConstraint.constant
+                        if anchor.referenceGuide == .safeArea {
+                            pos += safeAreaInsets.left
+                        }
+                    case .right:
+                        pos = vc.view.bounds.width + animationConstraint.constant
+                        if anchor.referenceGuide == .safeArea {
+                            pos -= safeAreaInsets.right
+                        }
+                    default:
+                        fatalError("Unsupported reference edges")
+                    }
+                }
+            } else {
+                pos = displayTrunc(edgePosition(surfaceView.frame), by: surfaceView.fp_displayScale)
+            }
+            switch position {
+            case .top, .bottom:
+                return CGPoint(x: 0.0, y: pos)
+            case .left, .right:
+                return CGPoint(x: pos, y: 0.0)
+            }
+        }
+        set {
+            let pos = position.mainLocation(newValue)
+            if let constraint = interactionConstraint {
+                constraint.constant = pos
+            } else if let animationConstraint = attractionConstraint, let anchor = layout.anchors[vc.state] {
+                let refEdge = referenceEdge(of: anchor)
+                switch refEdge {
+                case .top, .left:
+                    animationConstraint.constant = pos
+                    if anchor.referenceGuide == .safeArea {
+                        animationConstraint.constant -= refEdge.inset(of: safeAreaInsets)
+                    }
+                case .bottom, .right:
+                    animationConstraint.constant = pos - position.mainDimension(vc.view.bounds.size)
+                    if anchor.referenceGuide == .safeArea {
+                        animationConstraint.constant += refEdge.inset(of: safeAreaInsets)
+                    }
+                }
+            } else {
+                switch position {
+                case .top:
+                    return surfaceView.frame.origin.y = pos - surfaceView.bounds.height
+                case .left:
+                    return surfaceView.frame.origin.x = pos - surfaceView.bounds.width
+                case .bottom:
+                    return surfaceView.frame.origin.y = pos
+                case .right:
+                    return surfaceView.frame.origin.x = pos
+                }
+            }
+        }
+    }
+
+    var offsetFromEdgeMost: CGFloat {
+        switch position {
+        case .top, .left:
+            return edgePosition(surfaceView.presentationFrame) - position(for: directionalMostState)
+        case .bottom, .right:
+            return position(for: directionalLeastState) - edgePosition(surfaceView.presentationFrame)
+        }
+    }
+
+    private var hiddenAnchor: FloatingPanelLayoutAnchoring {
+        switch position {
+        case .top:
+            return FloatingPanelLayoutAnchor(absoluteInset: -100, edge: .top, referenceGuide: .superview)
+        case .left:
+            return FloatingPanelLayoutAnchor(absoluteInset: -100, edge: .left, referenceGuide: .superview)
+        case .bottom:
+            return FloatingPanelLayoutAnchor(absoluteInset: -100, edge: .bottom, referenceGuide: .superview)
+        case .right:
+            return FloatingPanelLayoutAnchor(absoluteInset: -100, edge: .right, referenceGuide: .superview)
+        }
+    }
+
+    init(vc: FloatingPanelController,
+         surfaceView: SurfaceView,
+         backdropView: BackdropView,
+         layout: FloatingPanelLayout) {
+        self.vc = vc
+        self.layout = layout
+        self.surfaceView = surfaceView
+        self.backdropView = backdropView
+    }
+
+    func surfaceLocation(for state: FloatingPanelState) -> CGPoint {
+        let pos = displayTrunc(position(for: state), by: surfaceView.fp_displayScale)
+        switch layout.position {
+        case .top, .bottom:
+            return CGPoint(x: 0.0, y: pos)
+        case .left, .right:
+            return CGPoint(x: pos, y: 0.0)
+        }
+    }
+
+    func position(for state: FloatingPanelState) -> CGFloat {
+        let bounds = vc.view.bounds
+        let anchor = layout.anchors[state] ?? self.hiddenAnchor
+
+        switch anchor {
+        case let anchor as FloatingPanelIntrinsicLayoutAnchor:
+            let intrinsicLength = position.mainDimension(surfaceView.intrinsicContentSize)
+            let diff = anchor.isAbsolute ? anchor.offset : intrinsicLength * anchor.offset
+
+            switch position {
+            case .top, .left:
+                var base: CGFloat = 0.0
+                if anchor.referenceGuide == .safeArea {
+                    base += position.inset(safeAreaInsets)
+                }
+                return base + intrinsicLength - diff
+            case .bottom, .right:
+                var base = position.mainDimension(bounds.size)
+                if anchor.referenceGuide == .safeArea {
+                    base -= position.inset(safeAreaInsets)
+                }
+                return base - intrinsicLength + diff
+            }
+        case let anchor as FloatingPanelLayoutAnchor:
+            let referenceBounds = anchor.referenceGuide == .safeArea ? bounds.inset(by: safeAreaInsets) : bounds
+            let diff = anchor.isAbsolute ? anchor.inset : position.mainDimension(referenceBounds.size) * anchor.inset
+            switch anchor.referenceEdge {
+            case .top:
+                return referenceBounds.minY + diff
+            case .left:
+                return referenceBounds.minX + diff
+            case .bottom:
+                return referenceBounds.maxY - diff
+            case .right:
+                return referenceBounds.maxX - diff
+            }
+        default:
+            fatalError("Unsupported a FloatingPanelLayoutAnchoring object")
+        }
+    }
+
+    func isIntrinsicAnchor(state: FloatingPanelState) -> Bool {
+        return layout.anchors[state] is FloatingPanelIntrinsicLayoutAnchor
+    }
+
+    private func edgePosition(_ frame: CGRect) -> CGFloat {
+        switch position {
+        case .top:
+            return frame.maxY
+        case .left:
+            return frame.maxX
+        case .bottom:
+            return frame.minY
+        case .right:
+            return frame.minX
+        }
+    }
+
+    private func referenceEdge(of anchor: FloatingPanelLayoutAnchoring) -> FloatingPanelReferenceEdge {
+        switch anchor {
+        case is FloatingPanelIntrinsicLayoutAnchor:
+            switch position {
+            case .top: return .top
+            case .left: return .left
+            case .bottom: return .bottom
+            case .right: return .right
+            }
+        case let anchor as FloatingPanelLayoutAnchor:
+            return anchor.referenceEdge
+        default:
+            fatalError("Unsupported a FloatingPanelLayoutAnchoring object")
+        }
+    }
+
+    func prepareLayout() {
+        NSLayoutConstraint.deactivate(fixedConstraints)
+
+        surfaceView.translatesAutoresizingMaskIntoConstraints = false
+        backdropView.translatesAutoresizingMaskIntoConstraints = false
+
+        // Fixed constraints of surface and backdrop views
+        let surfaceConstraints: [NSLayoutConstraint]
+        if let constraints = layout.prepareLayout?(surfaceView: surfaceView, in: vc.view) {
+            surfaceConstraints = constraints
+        } else {
+            switch position {
+            case .top, .bottom:
+                surfaceConstraints = [
+                    surfaceView.leftAnchor.constraint(equalTo: vc.fp_safeAreaLayoutGuide.leftAnchor, constant: 0.0),
+                    surfaceView.rightAnchor.constraint(equalTo: vc.fp_safeAreaLayoutGuide.rightAnchor, constant: 0.0),
+                ]
+            case .left, .right:
+                surfaceConstraints = [
+                    surfaceView.topAnchor.constraint(equalTo: vc.fp_safeAreaLayoutGuide.topAnchor, constant: 0.0),
+                    surfaceView.bottomAnchor.constraint(equalTo: vc.fp_safeAreaLayoutGuide.bottomAnchor, constant: 0.0),
+                ]
+            }
+        }
+        let backdropConstraints = [
+            backdropView.topAnchor.constraint(equalTo: vc.view.topAnchor, constant: 0.0),
+            backdropView.leftAnchor.constraint(equalTo: vc.view.leftAnchor,constant: 0.0),
+            backdropView.rightAnchor.constraint(equalTo: vc.view.rightAnchor, constant: 0.0),
+            backdropView.bottomAnchor.constraint(equalTo: vc.view.bottomAnchor, constant: 0.0),
+            ]
+
+        fixedConstraints = surfaceConstraints + backdropConstraints
+
+        NSLayoutConstraint.deactivate(constraint: self.fitToBoundsConstraint)
+        self.fitToBoundsConstraint = nil
+
+        if vc.contentMode == .fitToBounds {
+            switch position {
+            case .top:
+                fitToBoundsConstraint = surfaceView.topAnchor.constraint(equalTo: vc.view.topAnchor, constant: 0.0)
+                fitToBoundsConstraint?.identifier = "FloatingPanel-fit-to-top"
+            case .left:
+                fitToBoundsConstraint = surfaceView.leftAnchor.constraint(equalTo: vc.view.leftAnchor, constant: 0.0)
+                fitToBoundsConstraint?.identifier = "FloatingPanel-fit-to-left"
+            case .bottom:
+                fitToBoundsConstraint = surfaceView.bottomAnchor.constraint(equalTo: vc.view.bottomAnchor, constant: 0.0)
+                fitToBoundsConstraint?.identifier = "FloatingPanel-fit-to-bottom"
+            case .right:
+                fitToBoundsConstraint = surfaceView.rightAnchor.constraint(equalTo: vc.view.rightAnchor, constant: 0.0)
+                fitToBoundsConstraint?.identifier = "FloatingPanel-fit-to-right"
+            }
+            fitToBoundsConstraint?.priority = .defaultHigh
+        }
+
+        updateStateConstraints()
+    }
+
+    private func updateStateConstraints() {
+        NSLayoutConstraint.deactivate(fullConstraints + halfConstraints + tipConstraints + offConstraints)
+
+        if let fullAnchor = layout.anchors[.full] {
+            fullConstraints = fullAnchor.layoutConstraints(vc, for: position)
+            fullConstraints.forEach {
+                $0.identifier = "FloatingPanel-full-constraint"
+            }
+        }
+        if let halfAnchor = layout.anchors[.half] {
+            halfConstraints = halfAnchor.layoutConstraints(vc, for: position)
+            halfConstraints.forEach {
+                $0.identifier = "FloatingPanel-half-constraint"
+            }
+        }
+        if let tipAnchors = layout.anchors[.tip] {
+            tipConstraints = tipAnchors.layoutConstraints(vc, for: position)
+            tipConstraints.forEach {
+                $0.identifier = "FloatingPanel-tip-constraint"
+            }
+        }
+        let hiddenAnchor = layout.anchors[.hidden] ?? self.hiddenAnchor
+        offConstraints = hiddenAnchor.layoutConstraints(vc, for: position)
+        offConstraints.forEach {
+            $0.identifier = "FloatingPanel-hidden-constraint"
+        }
+    }
+
+    func startInteraction(at state: FloatingPanelState, offset: CGPoint = .zero) {
+        if let constraint = interactionConstraint {
+            initialConst = constraint.constant
+            return
+        }
+
+        tearDownAttraction()
+
+        NSLayoutConstraint.deactivate(fullConstraints + halfConstraints + tipConstraints + offConstraints)
+
+        initialConst = edgePosition(surfaceView.frame) + offset.y
+
+        let constraint: NSLayoutConstraint
+        switch position {
+        case .top:
+            constraint = surfaceView.bottomAnchor.constraint(equalTo: vc.view.topAnchor, constant: initialConst)
+        case .left:
+            constraint = surfaceView.rightAnchor.constraint(equalTo: vc.view.leftAnchor, constant: initialConst)
+        case .bottom:
+            constraint = surfaceView.topAnchor.constraint(equalTo: vc.view.topAnchor, constant: initialConst)
+        case .right:
+            constraint = surfaceView.leftAnchor.constraint(equalTo: vc.view.leftAnchor, constant: initialConst)
+        }
+
+        constraint.priority = .defaultHigh
+        constraint.identifier = "FloatingPanel-interaction"
+
+        NSLayoutConstraint.activate([constraint])
+        self.interactionConstraint = constraint
+    }
+
+    func endInteraction(at state: FloatingPanelState) {
+        // Don't deactivate `interactiveTopConstraint` here because it leads to
+        // unsatisfiable constraints
+
+        if self.interactionConstraint == nil {
+            // Activate `interactiveTopConstraint` for `fitToBounds` mode.
+            // It goes through this path when the pan gesture state jumps
+            // from .begin to .end.
+            startInteraction(at: state)
+        }
+    }
+
+    func setUpAttraction(to state: FloatingPanelState) -> (NSLayoutConstraint, CGFloat) {
+        NSLayoutConstraint.deactivate(constraint: attractionConstraint)
+
+        let anchor = layout.anchors[state] ?? self.hiddenAnchor
+
+        NSLayoutConstraint.deactivate(fullConstraints + halfConstraints + tipConstraints + offConstraints)
+        NSLayoutConstraint.deactivate(constraint: interactionConstraint)
+        interactionConstraint = nil
+
+        let layoutGuideProvider: LayoutGuideProvider
+        switch anchor.referenceGuide {
+        case .safeArea:
+            layoutGuideProvider = vc.fp_safeAreaLayoutGuide
+        case .superview:
+            layoutGuideProvider = vc.view
+        }
+        let currentY = position.mainLocation(surfaceLocation)
+        let baseHeight = position.mainDimension(vc.view.bounds.size)
+
+        let animationConstraint: NSLayoutConstraint
+        var targetY = position(for: state)
+
+        switch position {
+        case .top:
+            switch referenceEdge(of: anchor) {
+            case .top:
+                animationConstraint = surfaceView.bottomAnchor.constraint(equalTo: layoutGuideProvider.topAnchor,
+                                                                          constant: currentY)
+                if anchor.referenceGuide == .safeArea {
+                    animationConstraint.constant -= safeAreaInsets.top
+                    targetY -= safeAreaInsets.top
+                }
+            case .bottom:
+                let baseHeight = vc.view.bounds.height
+                targetY = -(baseHeight - targetY)
+                animationConstraint = surfaceView.bottomAnchor.constraint(equalTo: layoutGuideProvider.bottomAnchor,
+                                                                          constant: -(baseHeight - currentY))
+                if anchor.referenceGuide == .safeArea {
+                    animationConstraint.constant += safeAreaInsets.bottom
+                    targetY += safeAreaInsets.bottom
+
+                }
+            default:
+                fatalError("Unsupported reference edges")
+            }
+        case .left:
+            switch referenceEdge(of: anchor) {
+            case .left:
+                animationConstraint = surfaceView.rightAnchor.constraint(equalTo: layoutGuideProvider.leftAnchor,
+                                                                          constant: currentY)
+                if anchor.referenceGuide == .safeArea {
+                    animationConstraint.constant -= safeAreaInsets.right
+                    targetY -= safeAreaInsets.right
+                }
+            case .right:
+                targetY = -(baseHeight - targetY)
+                animationConstraint = surfaceView.rightAnchor.constraint(equalTo: layoutGuideProvider.rightAnchor,
+                                                                          constant: -(baseHeight - currentY))
+                if anchor.referenceGuide == .safeArea {
+                    animationConstraint.constant += safeAreaInsets.left
+                    targetY += safeAreaInsets.left
+                }
+            default:
+                fatalError("Unsupported reference edges")
+            }
+        case .bottom:
+            switch referenceEdge(of: anchor) {
+            case .top:
+                animationConstraint = surfaceView.topAnchor.constraint(equalTo: layoutGuideProvider.topAnchor,
+                                                                       constant: currentY)
+                if anchor.referenceGuide == .safeArea {
+                    animationConstraint.constant -= safeAreaInsets.top
+                    targetY -= safeAreaInsets.top
+                }
+            case .bottom:
+                targetY = -(baseHeight - targetY)
+                animationConstraint = surfaceView.topAnchor.constraint(equalTo: layoutGuideProvider.bottomAnchor,
+                                                                       constant: -(baseHeight - currentY))
+                if anchor.referenceGuide == .safeArea {
+                    animationConstraint.constant += safeAreaInsets.bottom
+                    targetY += safeAreaInsets.bottom
+
+                }
+            default:
+                fatalError("Unsupported reference edges")
+            }
+        case .right:
+            switch referenceEdge(of: anchor) {
+            case .left:
+                animationConstraint = surfaceView.leftAnchor.constraint(equalTo: layoutGuideProvider.leftAnchor,
+                                                                         constant: currentY)
+                if anchor.referenceGuide == .safeArea {
+                    animationConstraint.constant -= safeAreaInsets.left
+                    targetY -= safeAreaInsets.left
+                }
+            case .right:
+                targetY = -(baseHeight - targetY)
+                animationConstraint = surfaceView.leftAnchor.constraint(equalTo: layoutGuideProvider.rightAnchor,
+                                                                         constant: -(baseHeight - currentY))
+                if anchor.referenceGuide == .safeArea {
+                    animationConstraint.constant += safeAreaInsets.right
+                    targetY += safeAreaInsets.right
+                }
+            default:
+                fatalError("Unsupported reference edges")
+            }
+        }
+
+        animationConstraint.priority = .defaultHigh
+        animationConstraint.identifier = "FloatingPanel-attraction"
+
+        NSLayoutConstraint.activate([animationConstraint])
+        self.attractionConstraint = animationConstraint
+        return (animationConstraint, targetY)
+    }
+
+    private func tearDownAttraction() {
+        NSLayoutConstraint.deactivate(constraint: attractionConstraint)
+        attractionConstraint = nil
+    }
+
+    // The method is separated from prepareLayout(to:) for the rotation support
+    // It must be called in FloatingPanelController.traitCollectionDidChange(_:)
+    func updateStaticConstraint() {
+        guard let vc = vc else { return }
+        NSLayoutConstraint.deactivate(constraint: staticConstraint)
+        staticConstraint = nil
+
+        if vc.contentMode == .fitToBounds {
+            surfaceView.containerOverflow = 0
+            return
+        }
+
+        let anchor = layout.anchors[self.edgeMostState]!
+        if anchor is FloatingPanelIntrinsicLayoutAnchor {
+            var constant = layout.position.mainDimension(surfaceView.intrinsicContentSize)
+            if anchor.referenceGuide == .safeArea {
+                constant += position.inset(safeAreaInsets)
+            }
+            staticConstraint = position.mainDimensionAnchor(surfaceView).constraint(equalToConstant: constant)
+        } else {
+            switch position {
+            case .top, .left:
+                staticConstraint = position.mainDimensionAnchor(surfaceView).constraint(equalToConstant: position(for: self.directionalMostState))
+            case .bottom, .right:
+                staticConstraint = position.mainDimensionAnchor(vc.view).constraint(equalTo: position.mainDimensionAnchor(surfaceView),
+                                                                                    constant: position(for: self.directionalLeastState))
+            }
+        }
+
+        switch position {
+        case .top, .bottom:
+            staticConstraint?.identifier = "FloatingPanel-static-height"
+        case .left, .right:
+            staticConstraint?.identifier = "FloatingPanel-static-width"
+        }
+
+        NSLayoutConstraint.activate(constraint: staticConstraint)
+
+        surfaceView.containerOverflow = position.mainDimension(vc.view.bounds.size)
+    }
+
+    func updateInteractiveEdgeConstraint(diff: CGFloat, overflow: Bool, allowsRubberBanding: (UIRectEdge) -> Bool) {
+        defer {
+            log.debug("update surface location = \(surfaceLocation)")
+        }
+
+        let minConst: CGFloat = position(for: directionalLeastState)
+        let maxConst: CGFloat = position(for: directionalMostState)
+
+        var const = initialConst + diff
+
+        let base = position.mainDimension(vc.view.bounds.size)
+        // Rubber-banding top buffer
+        if allowsRubberBanding(.top), const < minConst {
+            let buffer = minConst - const
+            const = minConst - rubberBandEffect(for: buffer, base: base)
+        }
+
+        // Rubber-banding bottom buffer
+        if allowsRubberBanding(.bottom), const > maxConst {
+            let buffer = const - maxConst
+            const = maxConst + rubberBandEffect(for: buffer, base: base)
+        }
+
+        if overflow == false {
+            const = min(max(const, minConst), maxConst)
+        }
+
+        interactionConstraint?.constant = const
+    }
+
+    // According to @chpwn's tweet: https://twitter.com/chpwn/status/285540192096497664
+    // x = distance from the edge
+    // c = constant value, UIScrollView uses 0.55
+    // d = dimension, either width or height
+    private func rubberBandEffect(for buffer: CGFloat, base: CGFloat) -> CGFloat {
+        return (1.0 - (1.0 / ((buffer * 0.55 / base) + 1.0))) * base
+    }
+
+    func activateLayout(for state: FloatingPanelState, forceLayout: Bool = false) {
+        defer {
+            if forceLayout {
+                layoutSurfaceIfNeeded()
+                log.debug("activateLayout for \(state) -- surface.presentation = \(self.surfaceView.presentationFrame) surface.frame = \(self.surfaceView.frame)")
+            } else {
+                log.debug("activateLayout for \(state)")
+            }
+        }
+
+        // Must deactivate `interactiveTopConstraint` here
+        NSLayoutConstraint.deactivate(constraint: self.interactionConstraint)
+        self.interactionConstraint = nil
+
+        tearDownAttraction()
+
+        NSLayoutConstraint.activate(fixedConstraints)
+
+        if vc.contentMode == .fitToBounds {
+            NSLayoutConstraint.activate(constraint: self.fitToBoundsConstraint)
+        }
+
+        var state = state
+
+        setBackdropAlpha(of: state)
+
+        if validStates.contains(state) == false {
+            state = layout.initialState
+        }
+
+        // Recalculate the intrinsic size of a content view. This is because
+        // UIView.systemLayoutSizeFitting() returns a different size between an
+        // on-screen and off-screen view which includes
+        // UIStackView(i.e. Settings view in Samples.app)
+        updateStateConstraints()
+        switch state {
+        case .full:
+            NSLayoutConstraint.activate(fullConstraints)
+        case .half:
+            NSLayoutConstraint.activate(halfConstraints)
+        case .tip:
+            NSLayoutConstraint.activate(tipConstraints)
+        case .hidden:
+            NSLayoutConstraint.activate(offConstraints)
+        default:
+            break
+        }
+    }
+
+    private func layoutSurfaceIfNeeded() {
+        #if !TEST
+        guard surfaceView.window != nil else { return }
+        #endif
+        surfaceView.superview?.layoutIfNeeded()
+    }
+
+    private func setBackdropAlpha(of target: FloatingPanelState) {
+        if target == .hidden {
+            self.backdropView.alpha = 0.0
+        } else {
+            self.backdropView.alpha = backdropAlpha(for: target)
+        }
+    }
+
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return layout.backdropAlpha?(for: state) ?? defaultLayout.backdropAlpha(for: state)
+    }
+
+    fileprivate func checkLayout() {
+        // Verify layout configurations
+        assert(activeStates.count > 0)
+        assert(validStates.contains(layout.initialState),
+               "Does not include an initial state (\(layout.initialState)) in (\(validStates))")
+        /* This assertion does not work in a device rotating
+         let statePosOrder = activeStates.sorted(by: { position(for: $0) < position(for: $1) })
+         assert(sortedDirectionalStates == statePosOrder,
+               "Check your layout anchors because the state order(\(statePosOrder)) must be (\(sortedDirectionalStates))).")
+         */
+    }
+}
+
+extension LayoutAdapter {
+    func segment(at pos: CGFloat, forward: Bool) -> LayoutSegment {
+        /// ----------------------->Y
+        /// --> forward                <-- backward
+        /// |-------|===o===|-------|  |-------|-------|===o===|
+        /// |-------|-------x=======|  |-------|=======x-------|
+        /// |-------|-------|===o===|  |-------|===o===|-------|
+        /// pos: o/x, segment: =
+
+        let sortedStates = sortedDirectionalStates
+
+        let upperIndex: Int?
+        if forward {
+            upperIndex = sortedStates.firstIndex(where: { pos < position(for: $0) })
+        } else {
+            upperIndex = sortedStates.firstIndex(where: { pos <= position(for: $0) })
+        }
+
+        switch upperIndex {
+        case 0:
+            return LayoutSegment(lower: nil, upper: sortedStates.first)
+        case let upperIndex?:
+            return LayoutSegment(lower: sortedStates[upperIndex - 1], upper: sortedStates[upperIndex])
+        default:
+            return LayoutSegment(lower: sortedStates[sortedStates.endIndex - 1], upper: nil)
+        }
+    }
+}
+
+extension FloatingPanelController {
+    var _layout: FloatingPanelLayout {
+        get {
+            floatingPanel.layoutAdapter.layout
+        }
+        set {
+            floatingPanel.layoutAdapter.layout = newValue
+            floatingPanel.layoutAdapter.checkLayout()
+        }
+    }
+}

Sources/LayoutAnchoring.swift

@@ -0,0 +1,138 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+
+/// An interface for implementing custom layout anchor objects.
+@objc public protocol FloatingPanelLayoutAnchoring {
+    var referenceGuide: FloatingPanelLayoutReferenceGuide { get }
+    func layoutConstraints(_ fpc: FloatingPanelController, for position: FloatingPanelPosition) -> [NSLayoutConstraint]
+}
+
+/// A layout anchor object that anchors a panel in a state.
+@objc final public class FloatingPanelLayoutAnchor: NSObject, FloatingPanelLayoutAnchoring /*, NSCopying */ {
+    /// Initializes and returns a layout anchor object to specify an absolute inset value for the position of a panel.
+    ///
+    /// The inset is a distance from the edge of the specified layout guide.
+    @objc public init(absoluteInset: CGFloat, edge: FloatingPanelReferenceEdge, referenceGuide: FloatingPanelLayoutReferenceGuide) {
+        self.inset = absoluteInset
+        self.referenceGuide = referenceGuide
+        self.referenceEdge = edge
+        self.isAbsolute = true
+    }
+    /// Initializes and returns a layout anchor object to specify a fractional inset value for the position of a panel.
+    ///
+    /// The inset is a distance from the edge of the specified layout guide. The value is a floating-point number
+    /// in the range 0.0 to 1.0, where 0.0 represents zero distance from the edge and 1.0 represents a distance
+    /// to the opposite edge.
+    @objc public init(fractionalInset: CGFloat, edge: FloatingPanelReferenceEdge, referenceGuide: FloatingPanelLayoutReferenceGuide) {
+        self.inset = fractionalInset
+        self.referenceGuide = referenceGuide
+        self.referenceEdge = edge
+        self.isAbsolute = false
+    }
+    let inset: CGFloat
+    let isAbsolute: Bool
+    /// The reference rectangle area for the inset.
+    @objc public let referenceGuide: FloatingPanelLayoutReferenceGuide
+    @objc let referenceEdge: FloatingPanelReferenceEdge
+}
+
+public extension FloatingPanelLayoutAnchor {
+    func layoutConstraints(_ vc: FloatingPanelController, for position: FloatingPanelPosition) -> [NSLayoutConstraint] {
+        let layoutGuide = referenceGuide.layoutGuide(vc: vc)
+        switch position {
+        case .top:
+            return layoutConstraints(layoutGuide, for: vc.surfaceView.bottomAnchor)
+        case .left:
+            return layoutConstraints(layoutGuide, for: vc.surfaceView.rightAnchor)
+        case .bottom:
+            return layoutConstraints(layoutGuide, for:  vc.surfaceView.topAnchor)
+        case .right:
+            return layoutConstraints(layoutGuide, for: vc.surfaceView.leftAnchor)
+        }
+    }
+
+    private func layoutConstraints(_ layoutGuide: LayoutGuideProvider, for edgeAnchor: NSLayoutYAxisAnchor) -> [NSLayoutConstraint] {
+        switch referenceEdge {
+        case .top:
+            if isAbsolute {
+                return [edgeAnchor.constraint(equalTo: layoutGuide.topAnchor, constant: inset)]
+            }
+            let offsetAnchor = layoutGuide.topAnchor.anchorWithOffset(to: edgeAnchor)
+            return [offsetAnchor.constraint(equalTo:layoutGuide.heightAnchor, multiplier: inset)]
+        case .bottom:
+            if isAbsolute {
+                return [layoutGuide.bottomAnchor.constraint(equalTo: edgeAnchor, constant: inset)]
+            }
+            let offsetAnchor = edgeAnchor.anchorWithOffset(to: layoutGuide.bottomAnchor)
+            return [offsetAnchor.constraint(equalTo: layoutGuide.heightAnchor, multiplier: inset)]
+        default:
+            fatalError("Unsupported reference edges")
+        }
+    }
+
+    private func layoutConstraints(_ layoutGuide: LayoutGuideProvider, for edgeAnchor: NSLayoutXAxisAnchor) -> [NSLayoutConstraint] {
+        switch referenceEdge {
+        case .left:
+            if isAbsolute {
+                return [edgeAnchor.constraint(equalTo: layoutGuide.leftAnchor, constant: inset)]
+            }
+            let offsetAnchor = layoutGuide.leftAnchor.anchorWithOffset(to: edgeAnchor)
+            return [offsetAnchor.constraint(equalTo: layoutGuide.widthAnchor, multiplier: inset)]
+        case .right:
+            if isAbsolute {
+                return [layoutGuide.rightAnchor.constraint(equalTo: edgeAnchor, constant: inset)]
+            }
+            let offsetAnchor = edgeAnchor.anchorWithOffset(to: layoutGuide.rightAnchor)
+            return [offsetAnchor.constraint(equalTo: layoutGuide.widthAnchor, multiplier: inset)]
+        default:
+            fatalError("Unsupported reference edges")
+        }
+    }
+}
+
+
+/// A layout anchor object that anchors a panel in a state using the intrinsic size for a content.
+@objc final public class FloatingPanelIntrinsicLayoutAnchor: NSObject, FloatingPanelLayoutAnchoring /*, NSCopying */ {
+    /// Initializes and returns a layout anchor object to specify an absolute offset value for the position of a panel.
+    ///
+    /// The offset is a distance from a position at which a panel displays the entire content.
+    @objc public init(absoluteOffset offset: CGFloat, referenceGuide: FloatingPanelLayoutReferenceGuide = .safeArea) {
+        self.offset = offset
+        self.referenceGuide = referenceGuide
+        self.isAbsolute = true
+    }
+
+    /// Initializes and returns a layout anchor object to specify a fractional offset value for the position of a panel.
+    ///
+    /// The offset value is a floating-point number in the range 0.0 to 1.0, where 0.0 represents the full content
+    /// is displayed and 0.5 represents the half of content is displayed.
+    @objc public init(fractionalOffset offset: CGFloat, referenceGuide: FloatingPanelLayoutReferenceGuide = .safeArea) {
+        self.offset = offset
+        self.referenceGuide = referenceGuide
+        self.isAbsolute = false
+    }
+    let offset: CGFloat
+    let isAbsolute: Bool
+
+    /// The reference rectangle area for the offset
+    @objc public let referenceGuide: FloatingPanelLayoutReferenceGuide
+}
+
+public extension FloatingPanelIntrinsicLayoutAnchor {
+    func layoutConstraints(_ vc: FloatingPanelController, for position: FloatingPanelPosition) -> [NSLayoutConstraint] {
+        let surfaceIntrinsicLength = position.mainDimension(vc.surfaceView.intrinsicContentSize)
+        let constant = isAbsolute ? surfaceIntrinsicLength - offset : surfaceIntrinsicLength * (1 - offset)
+        let layoutGuide = referenceGuide.layoutGuide(vc: vc)
+        switch position {
+        case .top:
+            return [vc.surfaceView.bottomAnchor.constraint(equalTo: layoutGuide.topAnchor, constant: constant)]
+        case .left:
+            return [vc.surfaceView.rightAnchor.constraint(equalTo: layoutGuide.leftAnchor, constant: constant)]
+        case .bottom:
+            return [vc.surfaceView.topAnchor.constraint(equalTo: layoutGuide.bottomAnchor, constant: -constant)]
+        case .right:
+            return [vc.surfaceView.leftAnchor.constraint(equalTo: layoutGuide.rightAnchor, constant: -constant)]
+        }
+    }
+}

Sources/LayoutReferences.swift

@@ -0,0 +1,45 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+
+/// Constants that specify the edge of the container of a panel.
+@objc public enum FloatingPanelReferenceEdge: Int {
+    case top
+    case left
+    case bottom
+    case right
+}
+
+extension FloatingPanelReferenceEdge {
+    func inset(of insets: UIEdgeInsets) -> CGFloat {
+        switch self {
+        case .top: return insets.top
+        case .left: return insets.left
+        case .bottom: return insets.bottom
+        case .right: return insets.right
+        }
+    }
+    func mainDimension(_ size: CGSize) -> CGFloat {
+        switch self {
+        case .top, .bottom: return size.height
+        case .left, .right: return size.width
+        }
+    }
+}
+
+/// Constants that specify a layout guide to lay out a panel.
+@objc public enum FloatingPanelLayoutReferenceGuide: Int {
+    case superview = 0
+    case safeArea = 1
+}
+
+extension FloatingPanelLayoutReferenceGuide {
+    func layoutGuide(vc: UIViewController) -> LayoutGuideProvider {
+        switch self {
+        case .safeArea:
+            return vc.fp_safeAreaLayoutGuide
+        case .superview:
+            return vc.view
+        }
+    }
+}

Sources/Logger.swift

@@ -1,7 +1,4 @@
-//
-//  Created by Shin Yamamoto on 2018/10/09.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import Foundation
 import os.log
@@ -23,9 +20,9 @@ struct Logger {
         var displayName: String {
             switch self {
             case .debug:
-                return "D/"
+                return "Debug:"
             case .info:
-                return "I/"
+                return "Info:"
             case .warning:
                 return "Warning:"
             case .error:
@@ -54,17 +51,18 @@ struct Logger {
         osLog = OSLog(subsystem: "com.scenee.FloatingPanel", category: "FloatingPanel")
     }
 
-    private func log(_ level: Level, _ message: Any, _ arguments: [Any], function: String, line: UInt) {
+    private func log(_ level: Level, _ message: Any, _ arguments: [Any], tag: String, function: String, line: UInt) {
         _ = s.wait(timeout: .now() + 0.033)
         defer { s.signal() }
 
         let extraMessage: String = arguments.map({ String(describing: $0) }).joined(separator: " ")
+        let _tag = tag.isEmpty ? "" : "\(tag):"
         let log: String = {
             switch level {
             case .debug:
-                return "\(level.displayName) \(message) \(extraMessage) (\(function):\(line))"
+                return "\(level.displayName)\(_tag) \(message) \(extraMessage) (\(function):\(line))"
             default:
-                return "\(level.displayName) \(message) \(extraMessage)"
+                return "\(level.displayName)\(_tag) \(message) \(extraMessage)"
             }
         }()
 
@@ -81,21 +79,21 @@ struct Logger {
         }
     }
 
-    func debug(_ log: Any, _ arguments: Any..., function: String = #function, file: String  = #file, line: UInt = #line) {
+    func debug(_ log: Any, _ arguments: Any..., tag: String = "", function: String = #function, file: String  = #file, line: UInt = #line) {
         #if __FP_LOG
-        self.log(.debug, log, arguments, function: getPrettyFunction(function, file), line: line)
+        self.log(.debug, log, arguments, tag: tag, function: getPrettyFunction(function, file), line: line)
         #endif
     }
 
-    func info(_ log: Any, _ arguments: Any..., function: String = #function, file: String  = #file, line: UInt = #line) {
-        self.log(.info, log, arguments, function: getPrettyFunction(function, file), line: line)
+    func info(_ log: Any, _ arguments: Any..., tag: String = "",  function: String = #function, file: String  = #file, line: UInt = #line) {
+        self.log(.info, log, arguments, tag: tag, function: getPrettyFunction(function, file), line: line)
     }
 
     func warning(_ log: Any, _ arguments: Any..., function: String = #function, file: String  = #file, line: UInt = #line) {
-        self.log(.warning, log, arguments, function: getPrettyFunction(function, file), line: line)
+        self.log(.warning, log, arguments, tag: "", function: getPrettyFunction(function, file), line: line)
     }
 
     func error(_ log: Any, _ arguments: Any..., function: String = #function, file: String  = #file, line: UInt = #line) {
-        self.log(.error, log, arguments, function: getPrettyFunction(function, file), line: line)
+        self.log(.error, log, arguments, tag: "", function: getPrettyFunction(function, file), line: line)
     }
 }

Sources/PassThroughView.swift

@@ -1,11 +1,9 @@
-//
-//  Created by Shin Yamamoto on 2018/11/21.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
-class FloatingPanelPassThroughView: UIView {
+@objc(FloatingPanelPassThroughView)
+class PassThroughView: UIView {
     public weak var eventForwardingView: UIView?
     public override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
         let hitView = super.hitTest(point, with: event)

Sources/Position.swift

@@ -0,0 +1,50 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+
+/// Constants describing the position of a panel in a screen
+@objc public enum FloatingPanelPosition: Int {
+    case top
+    case left
+    case bottom
+    case right
+}
+
+extension FloatingPanelPosition {
+    func mainLocation(_ point: CGPoint) -> CGFloat {
+        switch self {
+        case .top, .bottom: return point.y
+        case .left, .right: return point.x
+        }
+    }
+
+    func mainDimension(_ size: CGSize) -> CGFloat {
+        switch self {
+        case .top, .bottom: return size.height
+        case .left, .right: return size.width
+        }
+    }
+
+    func mainDimensionAnchor(_ layoutGuide: LayoutGuideProvider) -> NSLayoutDimension {
+        switch self {
+        case .top, .bottom: return layoutGuide.heightAnchor
+        case .left, .right: return layoutGuide.widthAnchor
+        }
+    }
+
+    func crossDimension(_ size: CGSize) -> CGFloat {
+        switch self {
+        case .top, .bottom: return size.width
+        case .left, .right: return size.height
+        }
+    }
+
+    func inset(_ insets: UIEdgeInsets) -> CGFloat {
+        switch self {
+        case .top: return insets.top
+        case .left: return insets.left
+        case .bottom: return insets.bottom
+        case .right: return insets.right
+        }
+    }
+}

Sources/State.swift

@@ -0,0 +1,63 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import Foundation
+
+/// An object that represents the display state of a panel in a screen.
+@objc
+public class FloatingPanelState: NSObject, NSCopying, RawRepresentable {
+    public typealias RawValue = String
+
+    required public init?(rawValue: RawValue) {
+        self.order = 0
+        self.rawValue = rawValue
+        super.init()
+    }
+
+    public init(rawValue: RawValue, order: Int) {
+        self.rawValue = rawValue
+        self.order = order
+        super.init()
+    }
+
+    /// The corresponding value of the raw type.
+    public let rawValue: RawValue
+    /// The sorting order for states
+    public let order: Int
+
+    public func copy(with zone: NSZone? = nil) -> Any {
+        return self
+    }
+
+    public override var description: String {
+        return rawValue
+    }
+
+    public override var debugDescription: String {
+        return description
+    }
+
+    /// A panel state indicates the entire panel is shown.
+    @objc(Full) public static let full: FloatingPanelState = FloatingPanelState(rawValue: "full", order: 1000)
+    /// A panel state indicates the half of a panel is shown.
+    @objc(Half) public static let half: FloatingPanelState = FloatingPanelState(rawValue: "half", order: 500)
+    /// A panel state indicates the tip of a panel is shown.
+    @objc(Tip) public static let tip: FloatingPanelState = FloatingPanelState(rawValue: "tip", order: 100)
+    /// A panel state indicates it is hidden.
+    @objc(Hidden) public static let hidden: FloatingPanelState = FloatingPanelState(rawValue: "hidden", order: 0)
+}
+
+extension FloatingPanelState {
+    func next(in states: [FloatingPanelState]) -> FloatingPanelState {
+        if let index = states.firstIndex(of: self), states.indices.contains(index + 1) {
+            return states[index + 1]
+        }
+        return self
+    }
+
+    func pre(in states: [FloatingPanelState]) -> FloatingPanelState {
+        if let index = states.firstIndex(of: self), states.indices.contains(index - 1) {
+            return states[index - 1]
+        }
+        return self
+    }
+}

Sources/SurfaceView.swift

@@ -0,0 +1,435 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+
+/// An object for customizing the appearance of a surface view
+@objc(FloatingPanelSurfaceAppearance)
+@objcMembers
+public class SurfaceAppearance: NSObject {
+
+    /// An object that represents information to render a shadow
+    @objc(FloatingPanelSurfaceAppearanceShadow)
+    public class Shadow: NSObject {
+        /// A Boolean indicating whether a shadow is displayed.
+        @objc
+        public var hidden: Bool = false
+
+        /// The color of a shadow.
+        @objc
+        public var color: UIColor = .black
+
+        /// The offset (in points) of a shadow.
+        @objc
+        public var offset: CGSize = CGSize(width: 0.0, height: 1.0)
+
+        /// The opacity of a shadow.
+        @objc
+        public var opacity: Float = 0.2
+
+        /// The blur radius (in points) used to render a shadow.
+        @objc
+        public var radius: CGFloat = 3
+
+        /// The inflated amount of a shadow prior to applying the blur.
+        @objc
+        public var spread: CGFloat = 0
+
+    }
+    /// The background color of a surface view
+    public var backgroundColor: UIColor? = {
+        if #available(iOS 13, *) {
+            return UIColor.systemBackground
+        } else {
+            return UIColor.white
+        }
+    }()
+
+    /// The radius to use when drawing the top rounded corners.
+    ///
+    /// `self.contentView` is masked with the top rounded corners automatically on iOS 11 and later.
+    /// On iOS 10, they are not automatically masked because of a UIVisualEffectView issue. See https://forums.developer.apple.com/thread/50854
+    public var cornerRadius: CGFloat = 0.0
+
+    /// An array of shadows used to create drop shadows underneath a surface view.
+    public var shadows: [Shadow] = [Shadow()]
+
+    /// The border width of a surface view.
+    public var borderColor: UIColor?
+
+    /// The border color of a surface view.
+    public var borderWidth: CGFloat = 0.0
+}
+
+/// A view that presents a surface interface in a panel.
+@objc(FloatingPanelSurfaceView)
+@objcMembers
+public class SurfaceView: UIView {
+    /// A `FloatingPanelGrabberView` object displayed at the top of the surface view.
+    ///
+    /// To use a custom grabber, hide this and then add it to the surface view at appropriate point.
+    public let grabberHandle = GrabberView()
+
+    /// Offset of the grabber handle from the interactive edge.
+    public var grabberHandlePadding: CGFloat = 6.0 { didSet {
+        setNeedsUpdateConstraints()
+    } }
+
+    /// The offset from the move edge to prevent the content scroll
+    public var grabberAreaOffset: CGFloat = 36.0
+
+    /// The grabber handle size
+    ///
+    /// On left/right positioned panel the width dimension is used as the height of `grabberHandle`, and vice versa.
+    public var grabberHandleSize: CGSize = CGSize(width: 36.0, height: 5.0) { didSet {
+        setNeedsUpdateConstraints()
+    } }
+
+    /// The content view to be assigned a view of the content view controller of `FloatingPanelController`
+    public weak var contentView: UIView?
+
+    /// The content insets specifying the insets around the content view.
+    public var contentPadding: UIEdgeInsets = .zero {
+        didSet {
+            // Needs update constraints
+            self.setNeedsUpdateConstraints()
+        }
+    }
+
+    public override var backgroundColor: UIColor? {
+        get { return appearance.backgroundColor }
+        set { appearance.backgroundColor = newValue; setNeedsLayout() }
+    }
+
+    /// The appearance settings for a surface view.
+    public var appearance = SurfaceAppearance() { didSet {
+        shadowLayers = appearance.shadows.map { _ in CAShapeLayer() }
+        setNeedsLayout()
+    }}
+
+    /// The margins to use when laying out the container view wrapping content.
+    public var containerMargins: UIEdgeInsets = .zero { didSet {
+        setNeedsUpdateConstraints()
+    } }
+
+    /// The view that displays an actual surface shape.
+    ///
+    /// It renders the background color, border line and top rounded corners,
+    /// specified by other properties. The reason why they're not be applied to
+    /// a content view directly is because it avoids any side-effects to the
+    /// content view.
+    public let containerView: UIView = UIView()
+
+    var containerOverflow: CGFloat = 0.0 { // Must not call setNeedsLayout()
+        didSet {
+            // Calling setNeedsUpdateConstraints() is necessary to fix a layout break
+            // when the contentMode is changed after laying out a panel, for instance,
+            // after calling viewDidAppear(_:) of the parent view controller.
+            setNeedsUpdateConstraints()
+        }
+    }
+
+    var position: FloatingPanelPosition = .bottom {
+        didSet {
+            guard position != oldValue else { return }
+            NSLayoutConstraint.deactivate([grabberHandleEdgePaddingConstraint,
+                                           grabberHandleCenterConstraint,
+                                           grabberHandleWidthConstraint,
+                                           grabberHandleHeightConstraint])
+            switch position {
+            case .top:
+                grabberHandleEdgePaddingConstraint = grabberHandle.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -grabberHandlePadding)
+                grabberHandleCenterConstraint = grabberHandle.centerXAnchor.constraint(equalTo: centerXAnchor)
+                grabberHandleWidthConstraint = grabberHandle.widthAnchor.constraint(equalToConstant: grabberHandleSize.width)
+                grabberHandleHeightConstraint = grabberHandle.heightAnchor.constraint(equalToConstant: grabberHandleSize.height)
+            case .left:
+                grabberHandleEdgePaddingConstraint = grabberHandle.rightAnchor.constraint(equalTo: rightAnchor, constant: -grabberHandlePadding)
+                grabberHandleCenterConstraint = grabberHandle.centerYAnchor.constraint(equalTo: centerYAnchor)
+                grabberHandleWidthConstraint = grabberHandle.widthAnchor.constraint(equalToConstant: grabberHandleSize.height)
+                grabberHandleHeightConstraint = grabberHandle.heightAnchor.constraint(equalToConstant: grabberHandleSize.width)
+            case .bottom:
+                grabberHandleEdgePaddingConstraint = grabberHandle.topAnchor.constraint(equalTo: topAnchor, constant: grabberHandlePadding)
+                grabberHandleCenterConstraint = grabberHandle.centerXAnchor.constraint(equalTo: centerXAnchor)
+                grabberHandleWidthConstraint = grabberHandle.widthAnchor.constraint(equalToConstant: grabberHandleSize.width)
+                grabberHandleHeightConstraint = grabberHandle.heightAnchor.constraint(equalToConstant: grabberHandleSize.height)
+            case .right:
+                grabberHandleEdgePaddingConstraint = grabberHandle.leftAnchor.constraint(equalTo: leftAnchor, constant: grabberHandlePadding)
+                grabberHandleCenterConstraint = grabberHandle.centerYAnchor.constraint(equalTo: centerYAnchor)
+                grabberHandleWidthConstraint = grabberHandle.widthAnchor.constraint(equalToConstant: grabberHandleSize.height)
+                grabberHandleHeightConstraint = grabberHandle.heightAnchor.constraint(equalToConstant: grabberHandleSize.width)
+            }
+            NSLayoutConstraint.activate([grabberHandleEdgePaddingConstraint,
+                                         grabberHandleCenterConstraint,
+                                         grabberHandleWidthConstraint,
+                                         grabberHandleHeightConstraint])
+            setNeedsUpdateConstraints()
+        }
+    }
+
+    var grabberAreaFrame: CGRect {
+        switch position {
+        case .top:
+            return CGRect(origin: .init(x: bounds.minX, y: bounds.maxY - grabberAreaOffset),
+                          size: .init(width: bounds.width, height: grabberAreaOffset))
+        case .left:
+            return CGRect(origin: .init(x: bounds.maxX - grabberAreaOffset, y: bounds.minY),
+                          size: .init(width: grabberAreaOffset, height: bounds.height))
+        case .bottom:
+            return CGRect(origin: CGPoint(x: bounds.minX, y: bounds.minY),
+                          size: CGSize(width: bounds.width, height: grabberAreaOffset))
+        case .right:
+            return CGRect(origin: .init(x: bounds.minX, y: bounds.minY),
+                          size: .init(width: grabberAreaOffset, height: bounds.height))
+        }
+    }
+
+    private lazy var containerViewTopConstraint = containerView.topAnchor.constraint(equalTo: topAnchor, constant: 0.0)
+    private lazy var containerViewLeftConstraint = containerView.leftAnchor.constraint(equalTo: leftAnchor, constant: 0.0)
+    private lazy var containerViewBottomConstraint = containerView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: 0.0)
+    private lazy var containerViewRightConstraint = containerView.rightAnchor.constraint(equalTo: rightAnchor, constant: 0.0)
+
+    /// The content view's top constraint
+    private var contentViewTopConstraint: NSLayoutConstraint?
+    /// The content view's left constraint
+    private var contentViewLeftConstraint: NSLayoutConstraint?
+    /// The content view's right constraint
+    private var contentViewRightConstraint: NSLayoutConstraint?
+    /// The content view's bottom constraint
+    private var contentViewBottomConstraint: NSLayoutConstraint?
+
+    private lazy var grabberHandleWidthConstraint = grabberHandle.widthAnchor.constraint(equalToConstant: grabberHandleSize.width)
+    private lazy var grabberHandleHeightConstraint = grabberHandle.heightAnchor.constraint(equalToConstant: grabberHandleSize.height)
+    private lazy var grabberHandleCenterConstraint =  grabberHandle.centerXAnchor.constraint(equalTo: centerXAnchor)
+    private lazy var grabberHandleEdgePaddingConstraint = grabberHandle.topAnchor.constraint(equalTo: topAnchor, constant: grabberHandlePadding)
+
+    private var shadowLayers: [CALayer] = [] {
+        willSet {
+            for shadowLayer in shadowLayers {
+                shadowLayer.removeFromSuperlayer()
+            }
+        }
+        didSet {
+            for shadowLayer in shadowLayers {
+                layer.insertSublayer(shadowLayer, at: 0)
+            }
+        }
+    }
+
+    public override class var requiresConstraintBasedLayout: Bool { return true }
+
+    override init(frame: CGRect) {
+        super.init(frame: frame)
+        addSubViews()
+    }
+
+    required public init?(coder aDecoder: NSCoder) {
+        super.init(coder: aDecoder)
+        addSubViews()
+    }
+
+    private func addSubViews() {
+        super.backgroundColor = .clear
+        self.clipsToBounds = false
+
+        addSubview(containerView)
+        containerView.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            containerViewTopConstraint,
+            containerViewLeftConstraint,
+            containerViewBottomConstraint,
+            containerViewRightConstraint,
+        ].map {
+            $0.identifier = "FloatingPanel-surface-container"
+            return $0;
+        })
+
+        addSubview(grabberHandle)
+        grabberHandle.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            grabberHandleEdgePaddingConstraint,
+            grabberHandleCenterConstraint,
+            grabberHandleWidthConstraint,
+            grabberHandleHeightConstraint,
+        ].map {
+            $0.identifier = "FloatingPanel-surface-grabber"
+            return $0;
+        })
+
+        shadowLayers = appearance.shadows.map { _ in CALayer() }
+    }
+
+    public override func updateConstraints() {
+        switch position {
+        case .top:
+            containerViewTopConstraint.constant = (containerMargins.top == 0) ? -containerOverflow : containerMargins.top
+            containerViewLeftConstraint.constant = containerMargins.left
+            containerViewRightConstraint.constant = -containerMargins.right
+            containerViewBottomConstraint.constant = -containerMargins.bottom
+        case .left:
+            containerViewTopConstraint.constant = containerMargins.top
+            containerViewLeftConstraint.constant = (containerMargins.left == 0) ? -containerOverflow : containerMargins.left
+            containerViewRightConstraint.constant = -containerMargins.right
+            containerViewBottomConstraint.constant = -containerMargins.bottom
+        case .bottom:
+            containerViewTopConstraint.constant = containerMargins.top
+            containerViewLeftConstraint.constant = containerMargins.left
+            containerViewRightConstraint.constant = -containerMargins.right
+            containerViewBottomConstraint.constant = (containerMargins.bottom == 0) ? containerOverflow : -containerMargins.bottom
+        case .right:
+            containerViewTopConstraint.constant = containerMargins.top
+            containerViewLeftConstraint.constant = containerMargins.left
+            containerViewRightConstraint.constant = (containerMargins.right == 0) ? containerOverflow : -containerMargins.right
+            containerViewBottomConstraint.constant = -containerMargins.bottom
+        }
+
+        contentViewTopConstraint?.constant = containerMargins.top + contentPadding.top
+        contentViewLeftConstraint?.constant = containerMargins.left + contentPadding.left
+        contentViewRightConstraint?.constant = containerMargins.right + contentPadding.right
+        contentViewBottomConstraint?.constant = containerMargins.bottom + contentPadding.bottom
+
+        switch position {
+        case .top, .left:
+            grabberHandleEdgePaddingConstraint.constant = -grabberHandlePadding
+        case .bottom, .right:
+            grabberHandleEdgePaddingConstraint.constant = grabberHandlePadding
+        }
+
+        switch position {
+        case .top, .bottom:
+            grabberHandleWidthConstraint.constant = grabberHandleSize.width
+            grabberHandleHeightConstraint.constant = grabberHandleSize.height
+        case .left, .right:
+            grabberHandleWidthConstraint.constant = grabberHandleSize.height
+            grabberHandleHeightConstraint.constant = grabberHandleSize.width
+       }
+
+        super.updateConstraints()
+    }
+
+    public override func layoutSubviews() {
+        super.layoutSubviews()
+        log.debug("surface view frame = \(frame)")
+
+        containerView.backgroundColor = appearance.backgroundColor
+
+        updateShadow()
+        updateCornerRadius()
+        updateBorder()
+
+        grabberHandle.layer.cornerRadius = grabberHandleSize.height / 2
+    }
+
+    public override var intrinsicContentSize: CGSize {
+        let fittingSize = UIView.layoutFittingCompressedSize
+        let contentSize = contentView?.systemLayoutSizeFitting(fittingSize) ?? .zero
+        return CGSize(width: containerMargins.horizontalInset + contentPadding.horizontalInset + contentSize.width,
+                      height: containerMargins.verticalInset + contentPadding.verticalInset + contentSize.height)
+    }
+
+    private func updateShadow() {
+        // Disable shadow animation when the surface's frame jumps to a new value.
+        CATransaction.begin()
+        CATransaction.setDisableActions(true)
+        for (i, shadow) in appearance.shadows.enumerated() {
+            let shadowLayer = shadowLayers[i]
+
+            shadowLayer.backgroundColor = UIColor.clear.cgColor
+            shadowLayer.frame = layer.bounds
+
+            let spread = shadow.spread
+            let shadowPath = UIBezierPath(roundedRect: containerView.frame.insetBy(dx: -spread,
+                                                                                   dy: -spread),
+                                          byRoundingCorners: [.allCorners],
+                                          cornerRadii: CGSize(width: appearance.cornerRadius, height: 0))
+            shadowLayer.shadowPath = shadowPath.cgPath
+            shadowLayer.shadowColor = shadow.color.cgColor
+            shadowLayer.shadowOffset = shadow.offset
+            // A shadow.radius value isn't manipulated by a scale(i.e. the display scale). It should be applied to the value by itself.
+            shadowLayer.shadowRadius = shadow.radius
+            shadowLayer.shadowOpacity = shadow.opacity
+
+            let mask = CAShapeLayer()
+            let path = UIBezierPath(roundedRect: containerView.frame,
+                                    byRoundingCorners: [.allCorners],
+                                    cornerRadii: CGSize(width: appearance.cornerRadius, height: 0))
+            let size = window?.bounds.size ?? CGSize(width: 1000.0, height: 1000.0)
+            path.append(UIBezierPath(rect: layer.bounds.insetBy(dx: -size.width,
+                                                                dy: -size.height)))
+            mask.fillRule = .evenOdd
+            mask.path = path.cgPath
+            if #available(iOS 13.0, *) {
+                mask.cornerCurve = containerView.layer.cornerCurve
+            }
+            shadowLayer.mask = mask
+        }
+        CATransaction.commit()
+    }
+
+    private func updateCornerRadius() {
+        containerView.layer.cornerRadius = appearance.cornerRadius
+        guard containerView.layer.cornerRadius != 0.0 else {
+            containerView.layer.masksToBounds = false
+            return
+        }
+        containerView.layer.masksToBounds = true
+        if position.inset(containerMargins) != 0 {
+            if #available(iOS 11, *) {
+                containerView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner,
+                                                     .layerMinXMaxYCorner, .layerMaxXMaxYCorner]
+            }
+            return
+        }
+        if #available(iOS 11, *) {
+            // Don't use `contentView.clipToBounds` because it prevents content view from expanding the height of a subview of it
+            // for the bottom overflow like Auto Layout settings of UIVisualEffectView in Main.storyboard of Example/Maps.
+            // Because the bottom of contentView must be fit to the bottom of a screen to work the `safeLayoutGuide` of a content VC.
+            switch position {
+            case .top:
+                containerView.layer.maskedCorners = [.layerMinXMaxYCorner, .layerMaxXMaxYCorner]
+            case .left:
+                containerView.layer.maskedCorners = [.layerMaxXMinYCorner, .layerMaxXMaxYCorner]
+            case .bottom:
+                containerView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
+            case .right:
+                containerView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMinXMaxYCorner]
+            }
+        } else {
+            // Can't use `containerView.layer.mask` because of a UIVisualEffectView issue in iOS 10, https://forums.developer.apple.com/thread/50854
+            // Instead, a user should display rounding corners appropriately.
+        }
+    }
+
+    private func updateBorder() {
+        containerView.layer.borderColor = appearance.borderColor?.cgColor
+        containerView.layer.borderWidth = appearance.borderWidth
+    }
+
+    func set(contentView: UIView) {
+        containerView.addSubview(contentView)
+        self.contentView = contentView
+        /* contentView.frame = bounds */ // MUST NOT: Because the top safe area inset of a content VC will be incorrect.
+        contentView.translatesAutoresizingMaskIntoConstraints = false
+
+        let topConstraint = contentView.topAnchor.constraint(equalTo: topAnchor, constant: containerMargins.top + contentPadding.top)
+        let leftConstraint = contentView.leftAnchor.constraint(equalTo: leftAnchor, constant: containerMargins.left + contentPadding.left)
+        let rightConstraint = rightAnchor.constraint(equalTo: contentView.rightAnchor, constant: containerMargins.right + contentPadding.right)
+        let bottomConstraint = bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: containerMargins.bottom + contentPadding.bottom)
+        NSLayoutConstraint.activate([
+            topConstraint,
+            leftConstraint,
+            rightConstraint,
+            bottomConstraint,
+        ].map {
+            $0.priority = .required - 1;
+            $0.identifier = "FloatingPanel-surface-content"
+            return $0;
+        })
+        self.contentViewTopConstraint = topConstraint
+        self.contentViewLeftConstraint = leftConstraint
+        self.contentViewRightConstraint = rightConstraint
+        self.contentViewBottomConstraint = bottomConstraint
+    }
+
+    func hasStackView() -> Bool {
+        return contentView?.subviews.reduce(false) { $0 || ($1 is UIStackView) } ?? false
+    }
+}

Sources/Transitioning.swift

@@ -1,36 +1,33 @@
-//
-//  Created by Shin Yamamoto on 2018/11/21.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
-class FloatingPanelModalTransition: NSObject, UIViewControllerTransitioningDelegate {
+class ModalTransition: NSObject, UIViewControllerTransitioningDelegate {
     func animationController(forPresented presented: UIViewController,
                              presenting: UIViewController,
                              source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
-        return FloatingPanelModalPresentTransition()
+        return ModalPresentTransition()
     }
 
     func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
-        return FloatingPanelModalDismissTransition()
+        return ModalDismissTransition()
     }
 
     func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
-        return FloatingPanelPresentationController(presentedViewController: presented, presenting: presenting)
+        return PresentationController(presentedViewController: presented, presenting: presenting)
     }
 }
 
-class FloatingPanelPresentationController: UIPresentationController {
+class PresentationController: UIPresentationController {
     override func presentationTransitionWillBegin() {
         // Must call here even if duplicating on in containerViewWillLayoutSubviews()
-        // Because it let the floating panel present correctly with the presentation animation
+        // Because it let the panel present correctly with the presentation animation
         addFloatingPanel()
     }
 
     override func presentationTransitionDidEnd(_ completed: Bool) {
         // For non-animated presentation
-        if let fpc = presentedViewController as? FloatingPanelController, fpc.position == .hidden {
+        if let fpc = presentedViewController as? FloatingPanelController, fpc.state == .hidden {
             fpc.show(animated: false, completion: nil)
         }
     }
@@ -38,7 +35,7 @@ class FloatingPanelPresentationController: UIPresentationController {
     override func dismissalTransitionDidEnd(_ completed: Bool) {
         if let fpc = presentedViewController as? FloatingPanelController {
             // For non-animated dismissal
-            if fpc.position != .hidden {
+            if fpc.state != .hidden {
                 fpc.hide(animated: false, completion: nil)
             }
             fpc.view.removeFromSuperview()
@@ -64,9 +61,7 @@ class FloatingPanelPresentationController: UIPresentationController {
         addFloatingPanel()
 
         // Forward touch events to the presenting view controller
-        (fpc.view as? FloatingPanelPassThroughView)?.eventForwardingView = presentingViewController.view
-
-        fpc.backdropView.dismissalTapGestureRecognizer.isEnabled = true
+        (fpc.view as? PassThroughView)?.eventForwardingView = presentingViewController.view
     }
 
     @objc func handleBackdrop(tapGesture: UITapGestureRecognizer) {
@@ -85,13 +80,14 @@ class FloatingPanelPresentationController: UIPresentationController {
     }
 }
 
-class FloatingPanelModalPresentTransition: NSObject, UIViewControllerAnimatedTransitioning {
+class ModalPresentTransition: NSObject, UIViewControllerAnimatedTransitioning {
     func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
         guard
             let fpc = transitionContext?.viewController(forKey: .to) as? FloatingPanelController
         else { fatalError()}
 
-        let animator = fpc.behavior.addAnimator(fpc, to: fpc.layout.initialPosition)
+        let animator = fpc.delegate?.floatingPanel?(fpc, animatorForPresentingTo: fpc.layout.initialState)
+            ?? FloatingPanelDefaultBehavior().addPanelAnimator(fpc, to: fpc.layout.initialState)
         return TimeInterval(animator.duration)
     }
 
@@ -106,13 +102,14 @@ class FloatingPanelModalPresentTransition: NSObject, UIViewControllerAnimatedTra
     }
 }
 
-class FloatingPanelModalDismissTransition: NSObject, UIViewControllerAnimatedTransitioning {
+class ModalDismissTransition: NSObject, UIViewControllerAnimatedTransitioning {
     func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
         guard
             let fpc = transitionContext?.viewController(forKey: .from) as? FloatingPanelController
         else { fatalError()}
 
-        let animator = fpc.behavior.removeAnimator(fpc, from: fpc.position)
+        let animator = fpc.delegate?.floatingPanel?(fpc, animatorForDismissingWith: .zero)
+            ?? FloatingPanelDefaultBehavior().removePanelAnimator(fpc, from: fpc.state, with: .zero)
         return TimeInterval(animator.duration)
     }
 

Sources/UIExtensions.swift

@@ -0,0 +1,203 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+
+internal func displayTrunc(_ v: CGFloat, by s: CGFloat) -> CGFloat {
+    let base = (1 / s)
+    let t = v.rounded(.down)
+    return t + ((v - t) / base).rounded(.toNearestOrAwayFromZero) * base
+}
+
+internal func displayEqual(_ lhs: CGFloat, _ rhs: CGFloat, by displayScale: CGFloat) -> Bool {
+    return displayTrunc(lhs, by: displayScale) == displayTrunc(rhs, by: displayScale)
+}
+
+protocol LayoutGuideProvider {
+    var topAnchor: NSLayoutYAxisAnchor { get }
+    var leftAnchor: NSLayoutXAxisAnchor { get }
+    var bottomAnchor: NSLayoutYAxisAnchor { get }
+    var rightAnchor: NSLayoutXAxisAnchor { get }
+    var widthAnchor: NSLayoutDimension { get }
+    var heightAnchor: NSLayoutDimension { get }
+}
+extension UILayoutGuide: LayoutGuideProvider {}
+extension UIView: LayoutGuideProvider {}
+
+private class CustomLayoutGuide: LayoutGuideProvider {
+    let topAnchor: NSLayoutYAxisAnchor
+    let leftAnchor: NSLayoutXAxisAnchor
+    let bottomAnchor: NSLayoutYAxisAnchor
+    let rightAnchor: NSLayoutXAxisAnchor
+    let widthAnchor: NSLayoutDimension
+    let heightAnchor: NSLayoutDimension
+    init(topAnchor: NSLayoutYAxisAnchor,
+         leftAnchor: NSLayoutXAxisAnchor,
+         bottomAnchor: NSLayoutYAxisAnchor,
+         rightAnchor: NSLayoutXAxisAnchor,
+         widthAnchor: NSLayoutDimension,
+         heightAnchor: NSLayoutDimension) {
+        self.topAnchor = topAnchor
+        self.leftAnchor = leftAnchor
+        self.bottomAnchor = bottomAnchor
+        self.rightAnchor = rightAnchor
+        self.widthAnchor = widthAnchor
+        self.heightAnchor = heightAnchor
+    }
+}
+
+extension UIViewController {
+    @objc var fp_safeAreaInsets: UIEdgeInsets {
+        if #available(iOS 11.0, *) {
+            return view.safeAreaInsets
+        } else {
+            return UIEdgeInsets(top: topLayoutGuide.length,
+                                left: 0.0,
+                                bottom: bottomLayoutGuide.length,
+                                right: 0.0)
+        }
+    }
+
+    var fp_safeAreaLayoutGuide: LayoutGuideProvider {
+        if #available(iOS 11.0, *) {
+            return view!.safeAreaLayoutGuide
+        } else {
+            return CustomLayoutGuide(topAnchor: topLayoutGuide.bottomAnchor,
+                                     leftAnchor: view.leftAnchor,
+                                     bottomAnchor: bottomLayoutGuide.topAnchor,
+                                     rightAnchor: view.rightAnchor,
+                                     widthAnchor: view.widthAnchor,
+                                     heightAnchor: topLayoutGuide.bottomAnchor.anchorWithOffset(to: bottomLayoutGuide.topAnchor))
+        }
+    }
+}
+
+// The reason why UIView has no extensions of safe area insets and top/bottom guides
+// is for iOS10 compatibility.
+extension UIView {
+    var fp_safeAreaLayoutGuide: LayoutGuideProvider {
+        if #available(iOS 11.0, *) {
+            return safeAreaLayoutGuide
+        } else {
+            return self
+        }
+    }
+
+    var presentationFrame: CGRect {
+        return layer.presentation()?.frame ?? frame
+    }
+
+    /// Returns non-zero displayScale
+    ///
+    /// On iOS 11 or earlier the `traitCollection.displayScale` of a view can be
+    /// 0.0(indicating unspecified) when its view hasn't been added yet into a view tree in a window.
+    /// So this method returns `UIScreen.main` scale if the scale value is zero, for testing mainly.
+    var fp_displayScale: CGFloat {
+        let ret = traitCollection.displayScale
+        if ret == 0.0 {
+            return UIScreen.main.scale
+        }
+        return ret
+    }
+}
+
+extension UIView {
+    func disableAutoLayout() {
+        let frame = self.frame
+        translatesAutoresizingMaskIntoConstraints = true
+        self.frame = frame
+    }
+    func enableAutoLayout() {
+        translatesAutoresizingMaskIntoConstraints = false
+    }
+
+    static func performWithLinear(startTime: Double = 0.0, relativeDuration: Double = 1.0, _ animations: @escaping (() -> Void)) {
+        UIView.animateKeyframes(withDuration: 0.0, delay: 0.0, options: [.calculationModeCubic], animations: {
+            UIView.addKeyframe(withRelativeStartTime: startTime, relativeDuration: relativeDuration, animations: animations)
+        }, completion: nil)
+    }
+}
+
+#if __FP_LOG
+extension UIGestureRecognizer.State: CustomDebugStringConvertible {
+    public var debugDescription: String {
+        switch self {
+        case .began: return "began"
+        case .changed: return "changed"
+        case .failed: return "failed"
+        case .cancelled: return "cancelled"
+        case .ended: return "ended"
+        case .possible: return "possible"
+        @unknown default: return ""
+        }
+    }
+}
+#endif
+
+extension UIScrollView {
+    var isLocked: Bool {
+        return !showsVerticalScrollIndicator && !bounces &&  isDirectionalLockEnabled
+    }
+    var fp_contentInset: UIEdgeInsets {
+        if #available(iOS 11.0, *) {
+            return adjustedContentInset
+        } else {
+            return contentInset
+        }
+    }
+    var fp_contentOffsetMax: CGPoint {
+        return CGPoint(x: max((contentSize.width + fp_contentInset.right) - bounds.width, 0.0),
+                       y: max((contentSize.height + fp_contentInset.bottom) - bounds.height, 0.0))
+    }
+}
+
+extension UISpringTimingParameters {
+    public convenience init(decelerationRate: CGFloat, frequencyResponse: CGFloat, initialVelocity: CGVector = .zero) {
+        let dampingRatio = CoreGraphics.log(decelerationRate) / (-4 * .pi * 0.001)
+        self.init(dampingRatio: dampingRatio, frequencyResponse: frequencyResponse, initialVelocity: initialVelocity)
+    }
+
+    public convenience init(dampingRatio: CGFloat, frequencyResponse: CGFloat, initialVelocity: CGVector = .zero) {
+        let mass = 1 as CGFloat
+        let stiffness = pow(2 * .pi / frequencyResponse, 2) * mass
+        let damp = 4 * .pi * dampingRatio * mass / frequencyResponse
+        self.init(mass: mass, stiffness: stiffness, damping: damp, initialVelocity: initialVelocity)
+    }
+}
+
+extension CGPoint {
+    static var leastNonzeroMagnitude: CGPoint {
+        return CGPoint(x: CGFloat.leastNonzeroMagnitude, y: CGFloat.leastNonzeroMagnitude)
+    }
+
+    static func + (lhs: CGPoint, rhs: CGPoint) -> CGPoint {
+        return CGPoint(x: lhs.x + rhs.x, y: lhs.y + rhs.y)
+    }
+
+    static func - (lhs: CGPoint, rhs: CGPoint) -> CGPoint {
+        return CGPoint(x: lhs.x - rhs.x, y: lhs.y - rhs.y)
+    }
+
+    static prefix func - (point: CGPoint) -> CGPoint {
+        return CGPoint(x: -point.x, y: -point.y)
+    }
+}
+
+extension NSLayoutConstraint {
+    static func activate(constraint: NSLayoutConstraint?) {
+        guard let constraint = constraint else { return }
+        self.activate([constraint])
+    }
+    static func deactivate(constraint: NSLayoutConstraint?) {
+        guard let constraint = constraint else { return }
+        self.deactivate([constraint])
+    }
+}
+
+extension UIEdgeInsets {
+    var horizontalInset: CGFloat {
+        return self.left + self.right
+    }
+    var verticalInset: CGFloat {
+        return self.top + self.bottom
+    }
+}

Tests/ControllerTests.swift

@@ -0,0 +1,352 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import XCTest
+@testable import FloatingPanel
+
+class ControllerTests: XCTestCase {
+    override func setUp() {}
+    override func tearDown() {}
+
+    func test_warningRetainCycle() {
+        let exp = expectation(description: "Warning retain cycle")
+        exp.expectedFulfillmentCount = 2 // For layout & behavior logs
+        log.hook = {(log, level) in
+            if log.contains("A memory leak will occur by a retain cycle because") {
+                XCTAssert(level == .warning)
+                exp.fulfill()
+            }
+        }
+        let myVC = MyZombieViewController(nibName: nil, bundle: nil)
+        myVC.loadViewIfNeeded()
+        wait(for: [exp], timeout: 10)
+    }
+
+    func test_addPanel() {
+        guard let rootVC = UIApplication.shared.keyWindow?.rootViewController else { fatalError() }
+        let fpc = FloatingPanelController()
+        fpc.addPanel(toParent: rootVC)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .half).y)
+        fpc.move(to: .tip, animated: false)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .tip).y)
+    }
+
+    @available(iOS 12.0, *)
+    func test_updateLayout_willTransition() {
+        class MyDelegate: FloatingPanelControllerDelegate {
+            func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+                if newCollection.userInterfaceStyle == .dark {
+                    XCTFail()
+                }
+                return FloatingPanelBottomLayout()
+            }
+        }
+        let myDelegate = MyDelegate()
+        let fpc = FloatingPanelController(delegate: myDelegate)
+        let traitCollection = UITraitCollection(traitsFrom: [fpc.traitCollection,
+                                                             UITraitCollection(userInterfaceStyle: .dark)])
+        XCTAssertEqual(traitCollection.userInterfaceStyle, .dark)
+    }
+
+    func test_moveTo() {
+        let delegate = FloatingPanelTestDelegate()
+        let fpc = FloatingPanelController(delegate: delegate)
+        XCTAssertEqual(delegate.position, .hidden)
+        fpc.showForTest()
+        XCTAssertEqual(delegate.position, .half)
+
+        fpc.hide()
+        XCTAssertEqual(delegate.position, .hidden)
+        
+        fpc.move(to: .full, animated: false)
+        XCTAssertEqual(fpc.state, .full)
+        XCTAssertEqual(delegate.position, .full)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .full).y)
+
+        fpc.move(to: .half, animated: false)
+        XCTAssertEqual(fpc.state, .half)
+        XCTAssertEqual(delegate.position, .half)
+
+        XCTAssertEqual(fpc.surfaceLocation, fpc.surfaceLocation(for: .half))
+
+        fpc.move(to: .tip, animated: false)
+        XCTAssertEqual(fpc.state, .tip)
+        XCTAssertEqual(delegate.position, .tip)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .tip).y)
+
+        fpc.move(to: .hidden, animated: false)
+        XCTAssertEqual(fpc.state, .hidden)
+        XCTAssertEqual(delegate.position, .hidden)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .hidden).y)
+
+        XCTContext.runActivity(named: "move to full(animated)") { act in
+            let exp = expectation(description: act.name)
+            fpc.move(to: .full, animated: true) {
+                XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .full).y)
+                exp.fulfill()
+            }
+            XCTAssertEqual(fpc.state, .full)
+            XCTAssertEqual(delegate.position, .full)
+            wait(for: [exp], timeout: 1.0)
+        }
+
+        XCTContext.runActivity(named: "move to half(animated)") { act in
+            let exp = expectation(description: act.name)
+            fpc.move(to: .half, animated: true) {
+                XCTAssertEqual(fpc.surfaceLocation, fpc.surfaceLocation(for: .half))
+                exp.fulfill()
+            }
+            XCTAssertEqual(fpc.state, .half)
+            XCTAssertEqual(delegate.position, .half)
+            wait(for: [exp], timeout: 1.0)
+        }
+
+        XCTContext.runActivity(named: "move to tip(animated)") { act in
+            let exp = expectation(description: act.name)
+            fpc.move(to: .tip, animated: true) {
+                XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .tip).y)
+                exp.fulfill()
+            }
+            XCTAssertEqual(fpc.state, .tip)
+            XCTAssertEqual(delegate.position, .tip)
+            wait(for: [exp], timeout: 1.0)
+        }
+
+        fpc.move(to: .hidden, animated: true)
+        XCTAssertEqual(fpc.state, .hidden)
+        XCTAssertEqual(delegate.position, .hidden)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .hidden).y)
+    }
+
+    func test_moveTo_bottomEdge() {
+        class MyFloatingPanelTop2BottomLayout: FloatingPanelTop2BottomTestLayout {
+            override var initialState: FloatingPanelState { return .half }
+        }
+        let delegate = FloatingPanelTestDelegate()
+        let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = MyFloatingPanelTop2BottomLayout()
+        XCTAssertEqual(delegate.position, .hidden)
+        fpc.showForTest()
+        XCTAssertEqual(delegate.position, .half)
+
+        fpc.hide()
+        XCTAssertEqual(delegate.position, .hidden)
+
+        fpc.move(to: .full, animated: false)
+        XCTAssertEqual(fpc.state, .full)
+        XCTAssertEqual(delegate.position, .full)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .full).y)
+
+        fpc.move(to: .half, animated: false)
+        XCTAssertEqual(fpc.state, .half)
+        XCTAssertEqual(delegate.position, .half)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .half).y)
+
+        fpc.move(to: .tip, animated: false)
+        XCTAssertEqual(fpc.state, .tip)
+        XCTAssertEqual(delegate.position, .tip)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .tip).y)
+
+        fpc.move(to: .hidden, animated: false)
+        XCTAssertEqual(fpc.state, .hidden)
+        XCTAssertEqual(delegate.position, .hidden)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .hidden).y)
+
+        XCTContext.runActivity(named: "move to full(animated)") { act in
+            let exp = expectation(description: act.name)
+            fpc.move(to: .full, animated: true) {
+                XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .full).y)
+                exp.fulfill()
+            }
+            XCTAssertEqual(fpc.state, .full)
+            XCTAssertEqual(delegate.position, .full)
+            wait(for: [exp], timeout: 1.0)
+        }
+
+        XCTContext.runActivity(named: "move to half(animated)") { act in
+            let exp = expectation(description: act.name)
+            fpc.move(to: .half, animated: true) {
+                XCTAssertEqual(fpc.surfaceLocation, fpc.surfaceLocation(for: .half))
+                exp.fulfill()
+            }
+            XCTAssertEqual(fpc.state, .half)
+            XCTAssertEqual(delegate.position, .half)
+            wait(for: [exp], timeout: 1.0)
+        }
+
+        XCTContext.runActivity(named: "move to tip(animated)") { act in
+            let exp = expectation(description: act.name)
+            fpc.move(to: .tip, animated: true) {
+                XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .tip).y)
+                exp.fulfill()
+            }
+            XCTAssertEqual(fpc.state, .tip)
+            XCTAssertEqual(delegate.position, .tip)
+            wait(for: [exp], timeout: 1.0)
+        }
+
+        fpc.move(to: .hidden, animated: true)
+        XCTAssertEqual(fpc.state, .hidden)
+        XCTAssertEqual(delegate.position, .hidden)
+        XCTAssertEqual(fpc.surfaceLocation.y, fpc.surfaceLocation(for: .hidden).y)
+    }
+    
+    func test_moveWithNearbyPosition() {
+        let delegate = FloatingPanelTestDelegate()
+        let fpc = FloatingPanelController(delegate: delegate)
+        XCTAssertEqual(delegate.position, .hidden)
+        fpc.showForTest()
+        
+        XCTAssertEqual(fpc.nearbyState, .half)
+        
+        fpc.hide()
+        XCTAssertEqual(fpc.nearbyState, .tip)
+        
+        fpc.move(to: .full, animated: false)
+        XCTAssertEqual(fpc.nearbyState, .full)
+        XCTAssertEqual(fpc.surfaceView.frame.minY, fpc.surfaceLocation(for: .full).y)
+    }
+
+    func test_moveTo_didMoveDelegate() {
+        let delegate = FloatingPanelTestDelegate()
+        let fpc = FloatingPanelController(delegate: delegate)
+        XCTAssertEqual(delegate.position, .hidden)
+        fpc.showForTest()
+
+        XCTContext.runActivity(named: "move(to:animated:false") { act in
+            let exp = expectation(description: act.name)
+            exp.expectedFulfillmentCount = 1
+            var count = 0
+            delegate.didMoveCallback = { _ in
+                count += 1
+                exp.fulfill()
+            }
+            fpc.move(to: .full, animated: false)
+            wait(for: [exp], timeout: 1.0)
+
+            XCTAssertEqual(count, 1)
+        }
+
+        XCTContext.runActivity(named: "move(to:animated:true)") { act in
+            let exp = expectation(description: act.name)
+            exp.assertForOverFulfill = false
+            exp.expectedFulfillmentCount = 1
+            var count = 0
+            delegate.didMoveCallback = { _ in
+                count += 1
+            }
+            fpc.move(to: .half, animated: true) {
+                exp.fulfill()
+            }
+            wait(for: [exp], timeout: 1.0)
+
+            XCTAssertGreaterThan(count, 1)
+        }
+
+        XCTContext.runActivity(named: "move(to:animated:false) with animation") { act in
+            let exp = expectation(description: act.name)
+            exp.expectedFulfillmentCount = 1
+            var count = 0
+            delegate.didMoveCallback = { _ in
+                count += 1
+            }
+            UIView.animate(withDuration: 0.3) {
+                fpc.move(to: .full, animated: false) {
+                    exp.fulfill()
+                }
+            }
+            wait(for: [exp], timeout: 1.0)
+
+            XCTAssertEqual(count, 1)
+        }
+
+        XCTContext.runActivity(named: "move(to:animated:true) with animation") { act in
+            let exp = expectation(description: act.name)
+            exp.assertForOverFulfill = false
+            exp.expectedFulfillmentCount = 1
+            var count = 0
+            delegate.didMoveCallback = { _ in
+                count += 1
+            }
+            UIView.animate(withDuration: 0.3) {
+                fpc.move(to: .half, animated: true) {
+                    exp.fulfill()
+                }
+            }
+            wait(for: [exp], timeout: 1.0)
+
+            XCTAssertGreaterThan(count, 1)
+        }
+    }
+
+    func test_originSurfaceY() {
+        let fpc = FloatingPanelController(delegate: nil)
+        fpc.loadViewIfNeeded()
+        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
+        fpc.show(animated: false, completion: nil)
+
+        fpc.move(to: .full, animated: false)
+        XCTAssertEqual(fpc.surfaceLocation, fpc.surfaceLocation(for: .full))
+        fpc.move(to: .half, animated: false)
+        XCTAssertEqual(fpc.surfaceLocation, fpc.surfaceLocation(for: .half))
+        fpc.move(to: .tip, animated: false)
+        XCTAssertEqual(fpc.surfaceLocation, fpc.surfaceLocation(for: .tip))
+        fpc.move(to: .hidden, animated: false)
+        XCTAssertEqual(fpc.surfaceLocation, fpc.surfaceLocation(for: .hidden))
+    }
+
+    func test_contentMode() {
+        let fpc = FloatingPanelController(delegate: nil)
+        fpc.loadViewIfNeeded()
+        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
+        fpc.show(animated: false, completion: nil)
+
+        fpc.contentMode = .static
+
+        fpc.move(to: .full, animated: false)
+        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.surfaceLocation(for: .full).y)
+        fpc.move(to: .half, animated: false)
+        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.surfaceLocation(for: .full).y)
+        fpc.move(to: .tip, animated: false)
+        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.surfaceLocation(for: .full).y)
+
+        fpc.contentMode = .fitToBounds
+
+        fpc.move(to: .full, animated: false)
+        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.surfaceLocation(for: .full).y)
+        fpc.move(to: .half, animated: false)
+        print(1 / fpc.surfaceView.fp_displayScale)
+        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.surfaceLocation(for: .half).y)
+        fpc.move(to: .tip, animated: false)
+        XCTAssertEqual(fpc.surfaceView.frame.height, fpc.view.bounds.height - fpc.surfaceLocation(for: .tip).y)
+    }
+}
+
+private class MyZombieViewController: UIViewController, FloatingPanelLayout, FloatingPanelBehavior, FloatingPanelControllerDelegate {
+    var fpc: FloatingPanelController?
+    override func viewDidLoad() {
+        fpc = FloatingPanelController(delegate: self)
+        fpc?.addPanel(toParent: self)
+        fpc?.layout = self
+        fpc?.behavior = self
+    }
+    var position: FloatingPanelPosition {
+        return .bottom
+    }
+    var initialState: FloatingPanelState {
+        return .half
+    }
+
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: UIScreen.main.bounds.height == 667.0 ? 18.0 : 16.0,
+                                             edge: .top,
+                                             referenceGuide: .superview),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 250.0,
+                                             edge: .bottom,
+                                             referenceGuide: .superview),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 60.0,
+                                            edge: .bottom,
+                                            referenceGuide: .superview),
+        ]
+    }
+}

Tests/CoreTests.swift

@@ -1,12 +1,9 @@
-//
-//  Created by Shin Yamamoto on 2019/05/23.
-//  Copyright © 2019 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import XCTest
 @testable import FloatingPanel
 
-class FloatingPanelTests: XCTestCase {
+class CoreTests: XCTestCase {
     override func setUp() {}
     override func tearDown() {}
 
@@ -20,7 +17,7 @@ class FloatingPanelTests: XCTestCase {
         fpc.track(scrollView: contentVC1.tableView)
         fpc.showForTest()
 
-        XCTAssertEqual(fpc.position, .half)
+        XCTAssertEqual(fpc.state, .half)
         XCTAssertEqual(contentVC1.tableView.showsVerticalScrollIndicator, false)
         XCTAssertEqual(contentVC1.tableView.bounces, false)
 
@@ -55,112 +52,155 @@ class FloatingPanelTests: XCTestCase {
         fpc.set(contentViewController: contentVC2)
         fpc.track(scrollView: contentVC2.tableView)
         fpc.show(animated: false, completion: nil)
-        XCTAssertEqual(fpc.position, .half)
+        XCTAssertEqual(fpc.state, .half)
         XCTAssertEqual(contentVC2.tableView.showsVerticalScrollIndicator, false)
         XCTAssertEqual(contentVC2.tableView.bounces, false)
     }
 
     func test_getBackdropAlpha_1positions() {
-        class FloatingPanelLayout1Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .full
-            let supportedPositions: Set<FloatingPanelPosition> = [.full]
+        class FloatingPanelLayout1Positions: FloatingPanelLayout {
+            let initialState: FloatingPanelState = .full
+            let position: FloatingPanelPosition = .bottom
+            var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+                return [.full: FloatingPanelLayoutAnchor(absoluteInset: 20.0, edge: .top, referenceGuide: .superview)]
+            }
         }
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout1Positions()
 
+        let delegate = FloatingPanelTestDelegate()
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout1Positions()
+
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
+        let fullPos = fpc.surfaceLocation(for: .full).y
 
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos - 100.0, with: CGPoint(x: 0.0, y: -100.0)), 0.3)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: CGPoint(x: 0.0, y: 0.0)), 0.3)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos + 100.0, with: CGPoint(x: 0.0, y: 100.0)), 0.3) // ok??
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos - 100.0, with: -100.0), 0.3)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: 0), 0.3)
+        XCTAssertLessThan(fpc.floatingPanel.getBackdropAlpha(at: fullPos + 100.0, with: 100.0), 0.3)
+    }
+
+    func test_getBackdropAlpha_1positionsWithInitialHidden() {
+        class FloatingPanelLayout2Positions: FloatingPanelTestLayout {
+            override var initialState: FloatingPanelState { .hidden }
+            override var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+                return [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: fullInset, edge: .top, referenceGuide: referenceGuide),
+                ]
+            }
+        }
+        let delegate = FloatingPanelTestDelegate()
+        let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout2Positions()
+
+        fpc.showForTest()
+
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let hiddenPos = fpc.surfaceLocation(for: .hidden).y
+
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos - 100.0, with:  -100.0), 0.3)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: 0.0), 0.3)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: hiddenPos, with: 100.0), 0.0)
     }
 
     func test_getBackdropAlpha_2positions() {
-        class FloatingPanelLayout2Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .half
-            let supportedPositions: Set<FloatingPanelPosition> = [.half, .full]
+        class FloatingPanelLayout2Positions: FloatingPanelLayout {
+            let initialState: FloatingPanelState = .half
+            let position: FloatingPanelPosition = .bottom
+            var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+                return [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: 20.0, edge: .top, referenceGuide: .superview),
+                    .half: FloatingPanelLayoutAnchor(absoluteInset: 250.0, edge: .bottom, referenceGuide: .superview),
+                ]
+            }
         }
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout2Positions()
 
+        let delegate = FloatingPanelTestDelegate()
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout2Positions()
+
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let halfPos = fpc.originYOfSurface(for: .half)
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let halfPos = fpc.surfaceLocation(for: .half).y
         let distance1 = abs(halfPos - fullPos)
 
         fpc.move(to: .full, animated: false)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: CGPoint(x: 0.0, y: 0.0)), 0.3)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos + distance1 * 0.5, with: CGPoint(x: 0.0, y: distance1 * 0.5)), 0.3 * 0.5)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: CGPoint(x: 0.0, y: distance1)), 0.0)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: 0.0), 0.3)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos + distance1 * 0.5, with: distance1), 0.3 * 0.5)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: distance1), 0.0)
 
         fpc.move(to: .half, animated: false)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: CGPoint(x: 0.0, y: 0.0)), 0.0)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos + distance1 * 0.5, with: CGPoint(x: 0.0, y: -0.5 * distance1)), 0.3 * 0.5)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: CGPoint(x: 0.0, y: -1 * distance1)), 0.3)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: 0.0), 0.0)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos + distance1 * 0.5, with: -0.5 * distance1), 0.3 * 0.5)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: -1 * distance1), 0.3)
     }
 
     func test_getBackdropAlpha_2positionsWithHidden() {
         class FloatingPanelLayout2Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .hidden
-            let supportedPositions: Set<FloatingPanelPosition> = [.hidden, .full]
+            override var initialState: FloatingPanelState { .hidden }
+            override var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+                return [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: fullInset, edge: .top, referenceGuide: referenceGuide),
+                    .hidden: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .bottom, referenceGuide: referenceGuide),
+                ]
+            }
         }
         let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout2Positions()
-
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout2Positions()
+
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let hiddenPos = fpc.originYOfSurface(for: .hidden)
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let hiddenPos = fpc.surfaceLocation(for: .hidden).y
 
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos - 100.0, with: CGPoint(x: 0.0, y: -100.0)), 0.3)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: CGPoint(x: 0.0, y: 0.0)), 0.3)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: hiddenPos, with: CGPoint(x: 0.0, y: 100.0)), 0.0)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos - 100.0, with:  -100.0), 0.3)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: 0.0), 0.3)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: hiddenPos, with: 100.0), 0.0)
     }
 
     func test_getBackdropAlpha_3positions() {
         let fpc = FloatingPanelController()
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let halfPos = fpc.originYOfSurface(for: .half)
-        let tipPos = fpc.originYOfSurface(for: .tip)
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let halfPos = fpc.surfaceLocation(for: .half).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
         let distance1 = abs(halfPos - fullPos)
         let distance2 = abs(tipPos - halfPos)
 
         fpc.move(to: .full, animated: false)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: CGPoint(x: 0.0, y: 0.0)), 0.3)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos + distance1 * 0.5, with: CGPoint(x: 0.0, y: distance1 * 0.5)), 0.3 * 0.5)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: CGPoint(x: 0.0, y: distance1)), 0.0)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: 0.0), 0.3)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos + distance1 * 0.5, with: distance1 * 0.5), 0.3 * 0.5)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: distance1), 0.0)
 
         fpc.move(to: .half, animated: false)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: CGPoint(x: 0.0, y: 0.0)), 0.0)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos + distance1 * 0.5, with: CGPoint(x: 0.0, y: -0.5 * distance1)), 0.3 * 0.5)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: CGPoint(x: 0.0, y: -1 * distance1)), 0.3)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: 0.0), 0.0)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos + distance1 * 0.5, with: -0.5 * distance1), 0.3 * 0.5)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: fullPos, with: -1 * distance1), 0.3)
 
         fpc.move(to: .tip, animated: false)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: tipPos, with: CGPoint(x: 0.0, y: 0.0)), 0.0)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos + distance2 * 0.5, with: CGPoint(x: 0.0, y: -0.5 * distance2)), 0.0)
-        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: CGPoint(x: 0.0, y: -1 * distance2)), 0.0)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: tipPos, with: 0.0), 0.0)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos + distance2 * 0.5, with: -0.5 * distance2), 0.0)
+        XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: -1 * distance2), 0.0)
     }
 
     func test_targetPosition_1positions() {
-        class FloatingPanelLayout1Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .full
-            let supportedPositions: Set<FloatingPanelPosition> = [.full]
+        class FloatingPanelLayout1Positions: FloatingPanelLayout {
+            let initialState: FloatingPanelState = .full
+            let position: FloatingPanelPosition = .bottom
+            var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+                return [.full: FloatingPanelLayoutAnchor(absoluteInset: 20.0, edge: .top, referenceGuide: .superview)]
+            }
         }
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout1Positions()
 
+        let delegate = FloatingPanelTestDelegate()
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout1Positions()
+
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
+        let fullPos = fpc.surfaceLocation(for: .full).y
 
         fpc.move(to: .full, animated: false)
         assertTargetPosition(fpc.floatingPanel, with: [
@@ -175,18 +215,25 @@ class FloatingPanelTests: XCTestCase {
     }
 
     func test_targetPosition_2positions() {
-        class FloatingPanelLayout2Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .half
-            let supportedPositions: Set<FloatingPanelPosition> = [.half, .full]
+        class FloatingPanelLayout2Positions: FloatingPanelLayout {
+            let initialState: FloatingPanelState = .half
+            let position: FloatingPanelPosition = .bottom
+            var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+                return [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: 20.0, edge: .top, referenceGuide: .superview),
+                    .half: FloatingPanelLayoutAnchor(absoluteInset: 250.0, edge: .bottom, referenceGuide: .superview),
+                ]
+            }
         }
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout2Positions()
 
+        let delegate = FloatingPanelTestDelegate()
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout2Positions()
+
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let halfPos = fpc.originYOfSurface(for: .half)
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let halfPos = fpc.surfaceLocation(for: .half).y
 
         fpc.move(to: .full, animated: false)
         assertTargetPosition(fpc.floatingPanel, with: [
@@ -225,18 +272,25 @@ class FloatingPanelTests: XCTestCase {
     }
 
     func test_targetPosition_2positionsWithHidden() {
-        class FloatingPanelLayout2Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .hidden
-            let supportedPositions: Set<FloatingPanelPosition> = [.hidden, .full]
+        class FloatingPanelLayout2Positions: FloatingPanelLayout {
+            let initialState: FloatingPanelState = .hidden
+            let position: FloatingPanelPosition = .bottom
+            var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+                return [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: 20.0, edge: .top, referenceGuide: .superview),
+                    .hidden: FloatingPanelLayoutAnchor(absoluteInset: 0, edge: .bottom, referenceGuide: .superview),
+                ]
+            }
         }
-        let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout2Positions()
 
+        let delegate = FloatingPanelTestDelegate()
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout2Positions()
+
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let hiddenPos = fpc.originYOfSurface(for: .hidden)
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let hiddenPos = fpc.surfaceLocation(for: .hidden).y
 
         fpc.move(to: .full, animated: false)
         assertTargetPosition(fpc.floatingPanel, with: [
@@ -274,15 +328,16 @@ class FloatingPanelTests: XCTestCase {
             ])
     }
 
-    func test_targetPosition_2positionsFromFull() {
+    func test_targetPosition_3positionsFromFull() {
         let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout3Positions()
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout3Positions()
+
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let halfPos = fpc.originYOfSurface(for: .half)
-        let tipPos = fpc.originYOfSurface(for: .tip)
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let halfPos = fpc.surfaceLocation(for: .half).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
         // From .full
         fpc.move(to: .full, animated: false)
         assertTargetPosition(fpc.floatingPanel, with: [
@@ -314,18 +369,63 @@ class FloatingPanelTests: XCTestCase {
             (#line, tipPos + 500.0, CGPoint(x: 0.0, y: -100.0), .tip), // far from bottomMostState
             (#line, tipPos + 500.0, CGPoint(x: 0.0, y: 0.0), .tip), // far from bottomMostState
             (#line, tipPos + 500.0, CGPoint(x: 0.0, y: 100.0), .tip), // far from bottomMostState
-            ])
+        ])
+    }
+
+    func test_targetPosition_3positionsFromFull_bottomEdge() {
+        let delegate = FloatingPanelTestDelegate()
+        let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout3PositionsBottomEdge()
+
+        fpc.showForTest()
+
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let halfPos = fpc.surfaceLocation(for: .half).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
+        // From .full
+        fpc.move(to: .full, animated: false)
+        assertTargetPosition(fpc.floatingPanel, with: [
+            (#line, tipPos - 500.0, CGPoint(x: 0.0, y: -100.0), .tip), // far from topMostState
+            (#line, tipPos - 500.0, CGPoint(x: 0.0, y: 0.0), .tip), // far from topMostState
+            (#line, tipPos - 500.0, CGPoint(x: 0.0, y: 100.0), .tip), // far from topMostState
+            (#line, tipPos - 10.0, CGPoint(x: 0.0, y: 3000.0), .half), // block projecting to full at half
+            (#line, tipPos, CGPoint(x: 0.0, y: -100.0), .tip),
+            (#line, tipPos, CGPoint(x: 0.0, y: 0.0), .tip),
+            (#line, tipPos, CGPoint(x: 0.0, y: 500.0), .half), // project to half
+            (#line, tipPos, CGPoint(x: 0.0, y: 1000.0), .half), // block projecting to full at half
+            (#line, tipPos, CGPoint(x: 0.0, y: 3000.0), .half), // block projecting to full at half
+            (#line, tipPos + 10.0, CGPoint(x: 0.0, y: 100.0), .tip), // redirect
+            (#line, halfPos - 10.0, CGPoint(x: 0.0, y: -100.0), .half), // redirect
+            (#line, halfPos, CGPoint(x: 0.0, y: -1000.0), .tip), //project to tip
+            (#line, halfPos, CGPoint(x: 0.0, y: -100.0), .half),
+            (#line, halfPos, CGPoint(x: 0.0, y: 0.0), .half),
+            (#line, halfPos, CGPoint(x: 0.0, y: 100.0), .half),
+            (#line, halfPos, CGPoint(x: 0.0, y: 1000.0), .full), // project to full
+            (#line, halfPos + 10.0, CGPoint(x: 0.0, y: 100.0), .half), // redirect
+            (#line, fullPos - 10.0, CGPoint(x: 0.0, y: -100.0), .full), // redirect
+            (#line, fullPos, CGPoint(x: 0.0, y: -3000.0), .half), // block projecting to tip at half
+            (#line, fullPos, CGPoint(x: 0.0, y: -1000.0), .half), // block projecting to tip at half
+            (#line, fullPos, CGPoint(x: 0.0, y: -500.0), .half), // project to half
+            (#line, fullPos, CGPoint(x: 0.0, y: -100.0), .full),
+            (#line, fullPos, CGPoint(x: 0.0, y: 0.0), .full),
+            (#line, fullPos, CGPoint(x: 0.0, y: 100.0), .full),
+            (#line, fullPos + 10.0, CGPoint(x: 0.0, y: -3000.0), .half), // block projecting to tip at half
+            (#line, fullPos + 500.0, CGPoint(x: 0.0, y: -100.0), .full), // far from bottomMostState
+            (#line, fullPos + 500.0, CGPoint(x: 0.0, y: 0.0), .full), // far from bottomMostState
+            (#line, fullPos + 500.0, CGPoint(x: 0.0, y: 100.0), .full), // far from bottomMostState
+        ])
     }
 
     func test_targetPosition_3positionsFromHalf() {
         let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout3Positions()
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout3Positions()
+
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let halfPos = fpc.originYOfSurface(for: .half)
-        let tipPos = fpc.originYOfSurface(for: .tip)
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let halfPos = fpc.surfaceLocation(for: .half).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
         // From .half
         fpc.move(to: .half, animated: false)
         assertTargetPosition(fpc.floatingPanel, with: [
@@ -355,18 +455,61 @@ class FloatingPanelTests: XCTestCase {
             (#line, tipPos + 500.0, CGPoint(x: 0.0, y: -100.0), .tip), // far from bottomMostState
             (#line, tipPos + 500.0, CGPoint(x: 0.0, y: 0.0), .tip), // far from bottomMostState
             (#line, tipPos + 500.0, CGPoint(x: 0.0, y: 100.0), .tip), // far from bottomMostState
+        ])
+    }
+
+    func test_targetPosition_3positionsFromHalf_bottomEdge() {
+        let delegate = FloatingPanelTestDelegate()
+        let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout3PositionsBottomEdge()
+
+            fpc.showForTest()
+
+            let fullPos = fpc.surfaceLocation(for: .full).y
+            let halfPos = fpc.surfaceLocation(for: .half).y
+            let tipPos = fpc.surfaceLocation(for: .tip).y
+            // From .half
+            fpc.move(to: .half, animated: false)
+            assertTargetPosition(fpc.floatingPanel, with: [
+                (#line, tipPos - 500.0, CGPoint(x: 0.0, y: -100.0), .tip), // far from topMostState
+                (#line, tipPos - 500.0, CGPoint(x: 0.0, y: 0.0), .tip), // far from topMostState
+                (#line, tipPos - 500.0, CGPoint(x: 0.0, y: 100.0), .tip), // far from topMostState
+                (#line, tipPos, CGPoint(x: 0.0, y: -100.0), .tip),
+                (#line, tipPos, CGPoint(x: 0.0, y: 0.0), .tip),
+                (#line, tipPos, CGPoint(x: 0.0, y: 500.0), .half), // project to half
+                (#line, tipPos, CGPoint(x: 0.0, y: 1000.0), .half), // block projecting to full at half
+                (#line, tipPos, CGPoint(x: 0.0, y: 3000.0), .half), // block projecting to full at half
+                (#line, tipPos + 10.0, CGPoint(x: 0.0, y: 100.0), .tip), // redirect
+                (#line, halfPos - 10.0, CGPoint(x: 0.0, y: -100.0), .half), // redirect
+                (#line, halfPos, CGPoint(x: 0.0, y: -1000.0), .tip),// project to tip
+                (#line, halfPos, CGPoint(x: 0.0, y: -100.0), .half),
+                (#line, halfPos, CGPoint(x: 0.0, y: 0.0), .half),
+                (#line, halfPos, CGPoint(x: 0.0, y: 100.0), .half),
+                (#line, halfPos, CGPoint(x: 0.0, y: 1000.0), .full), // project to full
+                (#line, halfPos + 10.0, CGPoint(x: 0.0, y: 100.0), .half), // redirect
+                (#line, fullPos - 10.0, CGPoint(x: 0.0, y: -100.0), .full), // redirect
+                (#line, fullPos, CGPoint(x: 0.0, y: -3000.0), .half), // block projecting to tip at half
+                (#line, fullPos, CGPoint(x: 0.0, y: -1000.0), .half), // block projecting to tip at half
+                (#line, fullPos, CGPoint(x: 0.0, y: -500.0), .half), // project to half
+                (#line, fullPos, CGPoint(x: 0.0, y: -100.0), .full),
+                (#line, fullPos, CGPoint(x: 0.0, y: 0.0), .full),
+                (#line, fullPos, CGPoint(x: 0.0, y: 100.0), .full),
+                (#line, fullPos + 500.0, CGPoint(x: 0.0, y: -100.0), .full), // far from bottomMostState
+                (#line, fullPos + 500.0, CGPoint(x: 0.0, y: 0.0), .full), // far from bottomMostState
+                (#line, fullPos + 500.0, CGPoint(x: 0.0, y: 100.0), .full), // far from bottomMostState
             ])
     }
 
     func test_targetPosition_3positionsFromTip() {
         let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout3Positions()
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout3Positions()
+
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let halfPos = fpc.originYOfSurface(for: .half)
-        let tipPos = fpc.originYOfSurface(for: .tip)
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let halfPos = fpc.surfaceLocation(for: .half).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
 
         // From .tip
         fpc.move(to: .tip, animated: false)
@@ -397,20 +540,63 @@ class FloatingPanelTests: XCTestCase {
             (#line, tipPos + 500.0, CGPoint(x: 0.0, y: -100.0), .tip), // far from bottomMostState
             (#line, tipPos + 500.0, CGPoint(x: 0.0, y: 0.0), .tip), // far from bottomMostState
             (#line, tipPos + 500.0, CGPoint(x: 0.0, y: 100.0), .tip), // far from bottomMostState
+        ])
+    }
+
+    func test_targetPosition_3positionsFromTip_bottomEdge() {
+        let delegate = FloatingPanelTestDelegate()
+        let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout3PositionsBottomEdge()
+
+        fpc.showForTest()
+
+            let fullPos = fpc.surfaceLocation(for: .full).y
+            let halfPos = fpc.surfaceLocation(for: .half).y
+            let tipPos = fpc.surfaceLocation(for: .tip).y
+
+            // From .tip
+            fpc.move(to: .tip, animated: false)
+            assertTargetPosition(fpc.floatingPanel, with: [
+                (#line, tipPos - 500.0, CGPoint(x: 0.0, y: -100.0), .tip), // far from topMostState
+                (#line, tipPos - 500.0, CGPoint(x: 0.0, y: 0.0), .tip), // far from topMostState
+                (#line, tipPos - 500.0, CGPoint(x: 0.0, y: 100.0), .tip), // far from topMostState
+                (#line, tipPos, CGPoint(x: 0.0, y: -100.0), .tip),
+                (#line, tipPos, CGPoint(x: 0.0, y: 0.0), .tip),
+                (#line, tipPos, CGPoint(x: 0.0, y: 500.0), .half), // project to half
+                (#line, tipPos, CGPoint(x: 0.0, y: 1000.0), .half), // block projecting to tip at half
+                (#line, tipPos, CGPoint(x: 0.0, y: 3000.0), .half), // block projecting to tip at half
+                (#line, tipPos + 10.0, CGPoint(x: 0.0, y: 100.0), .tip), // redirect
+                (#line, halfPos - 10.0, CGPoint(x: 0.0, y: -100.0), .half), // redirect
+                (#line, halfPos, CGPoint(x: 0.0, y: -3000.0), .tip), // project to full
+                (#line, halfPos, CGPoint(x: 0.0, y: -100.0), .half),
+                (#line, halfPos, CGPoint(x: 0.0, y: 0.0), .half),
+                (#line, halfPos, CGPoint(x: 0.0, y: 100.0), .half),
+                (#line, halfPos, CGPoint(x: 0.0, y: 1000.0), .full), // project to tip
+                (#line, halfPos + 10.0, CGPoint(x: 0.0, y: 100.0), .half), // redirect
+                (#line, fullPos - 10.0, CGPoint(x: 0.0, y: -100.0), .full), // redirect
+                (#line, fullPos, CGPoint(x: 0.0, y: -3000.0), .half), // block projecting to full at half
+                (#line, fullPos, CGPoint(x: 0.0, y: -1000.0), .half), // block projecting to full at half
+                (#line, fullPos, CGPoint(x: 0.0, y: -500.0), .half), // project to half
+                (#line, fullPos, CGPoint(x: 0.0, y: -100.0), .full),
+                (#line, fullPos, CGPoint(x: 0.0, y: 0.0), .full),
+                (#line, fullPos, CGPoint(x: 0.0, y: 100.0), .full),
+                (#line, fullPos + 500.0, CGPoint(x: 0.0, y: -100.0), .full), // far from bottomMostState
+                (#line, fullPos + 500.0, CGPoint(x: 0.0, y: 0.0), .full), // far from bottomMostState
+                (#line, fullPos + 500.0, CGPoint(x: 0.0, y: 100.0), .full), // far from bottomMostState
             ])
     }
 
     func test_targetPosition_3positionsAllProjection() {
         let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout3Positions()
-        delegate.behavior = FloatingPanelProjectionalBehavior()
-
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout3Positions()
+        fpc.behavior = FloatingPanelProjectableBehavior()
+
         fpc.showForTest()
 
-        let fullPos = fpc.originYOfSurface(for: .full)
-        let halfPos = fpc.originYOfSurface(for: .half)
-        let tipPos = fpc.originYOfSurface(for: .tip)
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let halfPos = fpc.surfaceLocation(for: .half).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
 
         // From .full
         fpc.move(to: .full, animated: false)
@@ -449,16 +635,23 @@ class FloatingPanelTests: XCTestCase {
     }
 
     func test_targetPosition_3positionsWithHidden() {
-        class FloatingPanelLayout3PositionsWithHidden: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .hidden
-            let supportedPositions: Set<FloatingPanelPosition> = [.hidden, .half, .full]
+        class FloatingPanelLayout3PositionsWithHidden: FloatingPanelLayout {
+            let initialState: FloatingPanelState = .hidden
+            let position: FloatingPanelPosition = .bottom
+            var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+                return [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: 20.0, edge: .top, referenceGuide: .superview),
+                    .half: FloatingPanelLayoutAnchor(absoluteInset: 250.0, edge: .bottom, referenceGuide: .superview),
+                    .hidden: FloatingPanelLayoutAnchor(absoluteInset: 0, edge: .bottom, referenceGuide: .superview),
+                ]
+            }
         }
         let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout3PositionsWithHidden()
-
         let fpc = FloatingPanelController(delegate: delegate)
+        fpc.layout = FloatingPanelLayout3PositionsWithHidden()
+
         fpc.showForTest()
-        XCTAssertEqual(fpc.position, .hidden)
+        XCTAssertEqual(fpc.state, .hidden)
 
         fpc.move(to: .full, animated: false)
         assertTargetPosition(fpc.floatingPanel, with: [
@@ -474,22 +667,29 @@ class FloatingPanelTests: XCTestCase {
     }
 
     func test_targetPosition_3positionsWithHiddenWithoutFull() {
-        class FloatingPanelLayout3Positions: FloatingPanelTestLayout {
-            let initialPosition: FloatingPanelPosition = .hidden
-            let supportedPositions: Set<FloatingPanelPosition> = [.hidden, .tip, .half]
+        class FloatingPanelLayout3Positions: FloatingPanelLayout {
+            let initialState: FloatingPanelState = .hidden
+            let position: FloatingPanelPosition = .bottom
+            var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+                return [
+                    .half: FloatingPanelLayoutAnchor(absoluteInset: 250.0, edge: .bottom, referenceGuide: .superview),
+                    .tip: FloatingPanelLayoutAnchor(absoluteInset: 60.0, edge: .bottom, referenceGuide: .superview),
+                    .hidden: FloatingPanelLayoutAnchor(absoluteInset: 0, edge: .bottom, referenceGuide: .superview),
+                ]
+            }
         }
 
         let delegate = FloatingPanelTestDelegate()
-        delegate.layout = FloatingPanelLayout3Positions()
-        delegate.behavior = FloatingPanelProjectionalBehavior()
-
         let fpc = FloatingPanelController(delegate: delegate)
-        fpc.showForTest()
-        XCTAssertEqual(fpc.position, .hidden)
+        fpc.layout = FloatingPanelLayout3Positions()
 
-        let halfPos = fpc.originYOfSurface(for: .half)
-        let tipPos = fpc.originYOfSurface(for: .tip)
-        //let hiddenPos = fpc.originYOfSurface(for: .hidden)
+        fpc.showForTest()
+        fpc.behavior = FloatingPanelProjectableBehavior()
+        XCTAssertEqual(fpc.state, .hidden)
+
+        let halfPos = fpc.surfaceLocation(for: .half).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
+        //let hiddenPos = fpc.surfaceLocation(for: .hidden)
 
         fpc.move(to: .half, animated: false)
         assertTargetPosition(fpc.floatingPanel, with: [
@@ -518,20 +718,21 @@ class FloatingPanelTests: XCTestCase {
 }
 
 private class FloatingPanelLayout3Positions: FloatingPanelTestLayout {
-    let initialPosition: FloatingPanelPosition = .tip
-    let supportedPositions: Set<FloatingPanelPosition> = [.tip, .half, .full]
+    override var initialState: FloatingPanelState {
+        return .tip
+    }
 }
 
-private typealias TestParameter = (UInt, CGFloat,CGPoint, FloatingPanelPosition)
-private func assertTargetPosition(_ floatingPanel: FloatingPanelCore, with params: [TestParameter]) {
+private class FloatingPanelLayout3PositionsBottomEdge: FloatingPanelTop2BottomTestLayout {
+    override var initialState: FloatingPanelState {
+        return .tip
+    }
+}
+
+private typealias TestParameter = (UInt, CGFloat,  CGPoint, FloatingPanelState)
+private func assertTargetPosition(_ floatingPanel: Core, with params: [TestParameter]) {
     params.forEach { (line, pos, velocity, result) in
         floatingPanel.surfaceView.frame.origin.y = pos
-        XCTAssertEqual(floatingPanel.targetPosition(from: pos, with: velocity), result, line: line)
-    }
-}
-
-private class FloatingPanelProjectionalBehavior: FloatingPanelBehavior {
-    func shouldProjectMomentum(_ fpc: FloatingPanelController, for proposedTargetPosition: FloatingPanelPosition) -> Bool {
-        return true
+        XCTAssertEqual(floatingPanel.targetPosition(from: pos, with: velocity.y), result, line: line)
     }
 }

Tests/LayoutTests.swift

@@ -0,0 +1,662 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import XCTest
+@testable import FloatingPanel
+
+class LayoutTests: XCTestCase {
+    var fpc: FloatingPanelController!
+    override func setUp() {
+        fpc = FloatingPanelController(delegate: nil)
+        fpc.loadViewIfNeeded()
+        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
+    }
+    override func tearDown() {}
+
+    func test_layoutAdapter_topAndBottomMostState() {
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeMostState, .full)
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeLeastState, .tip)
+
+        class FloatingPanelLayoutWithHidden: FloatingPanelLayout {
+            var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring]  {
+                return [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: 18.0, edge: .top, referenceGuide: .safeArea),
+                    .half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
+                    .hidden: FloatingPanelLayoutAnchor(absoluteInset: 0, edge: .bottom, referenceGuide: .superview)
+                ]
+            }
+            let initialState: FloatingPanelState = .hidden
+            let position: FloatingPanelPosition = .bottom
+        }
+        class FloatingPanelLayout2Positions: FloatingPanelLayout {
+            var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring]  {
+                return [
+                    .half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
+                    .tip: FloatingPanelLayoutAnchor(absoluteInset: 69.0, edge: .bottom, referenceGuide: .safeArea),
+                ]
+            }
+            let initialState: FloatingPanelState = .tip
+            let position: FloatingPanelPosition = .bottom
+        }
+        fpc.layout = FloatingPanelLayoutWithHidden()
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeMostState, .full)
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeLeastState, .hidden)
+
+        fpc.layout = FloatingPanelLayout2Positions()
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeMostState, .half)
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeLeastState, .tip)
+    }
+
+    func test_layoutSegment_3position() {
+        class FloatingPanelLayout3Positions: FloatingPanelTestLayout {
+            override var initialState: FloatingPanelState  { .half }
+        }
+
+        fpc.layout = FloatingPanelLayout3Positions()
+
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let halfPos = fpc.surfaceLocation(for: .half).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
+
+        let minPos = CGFloat.leastNormalMagnitude
+        let maxPos = CGFloat.greatestFiniteMagnitude
+
+        assertLayoutSegment(fpc.floatingPanel, with: [
+            (#line, pos: minPos, forwardY: true, lower: nil, upper: .full),
+            (#line, pos: minPos, forwardY: false, lower: nil, upper: .full),
+            (#line, pos: fullPos, forwardY: true, lower: .full, upper: .half),
+            (#line, pos: fullPos, forwardY: false, lower: nil,  upper: .full),
+            (#line, pos: halfPos, forwardY: true, lower: .half, upper: .tip),
+            (#line, pos: halfPos, forwardY: false, lower: .full,  upper: .half),
+            (#line, pos: tipPos, forwardY: true, lower: .tip, upper: nil),
+            (#line, pos: tipPos, forwardY: false, lower: .half,  upper: .tip),
+            (#line, pos: maxPos, forwardY: true, lower: .tip, upper: nil),
+            (#line, pos: maxPos, forwardY: false, lower: .tip, upper: nil),
+            ])
+    }
+
+    func test_layoutSegment_2positions() {
+        class FloatingPanelLayout2Positions: FloatingPanelTestLayout {
+            override var initialState: FloatingPanelState  { .half }
+            override var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring]
+                { super.anchors.filter { (key, _) in key != .tip } }
+        }
+
+        fpc.layout = FloatingPanelLayout2Positions()
+
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let halfPos = fpc.surfaceLocation(for: .half).y
+
+        let minPos = CGFloat.leastNormalMagnitude
+        let maxPos = CGFloat.greatestFiniteMagnitude
+
+        assertLayoutSegment(fpc.floatingPanel, with: [
+            (#line, pos: minPos, forwardY: true, lower: nil, upper: .full),
+            (#line, pos: minPos, forwardY: false, lower: nil, upper: .full),
+            (#line, pos: fullPos, forwardY: true, lower: .full, upper: .half),
+            (#line, pos: fullPos, forwardY: false, lower: nil,  upper: .full),
+            (#line, pos: halfPos, forwardY: true, lower: .half, upper: nil),
+            (#line, pos: halfPos, forwardY: false, lower: .full,  upper: .half),
+            (#line, pos: maxPos, forwardY: true, lower: .half, upper: nil),
+            (#line, pos: maxPos, forwardY: false, lower: .half, upper: nil),
+            ])
+    }
+
+    func test_layoutSegment_1positions() {
+        class FloatingPanelLayout1Positions: FloatingPanelTestLayout {
+            override var initialState: FloatingPanelState  { .full }
+            override var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring]
+                { super.anchors.filter { (key, _) in key == .full } }
+        }
+
+        fpc.layout = FloatingPanelLayout1Positions()
+
+        let fullPos = fpc.surfaceLocation(for: .full).y
+
+        let minPos = CGFloat.leastNormalMagnitude
+        let maxPos = CGFloat.greatestFiniteMagnitude
+
+        assertLayoutSegment(fpc.floatingPanel, with: [
+            (#line, pos: minPos, forwardY: true, lower: nil, upper: .full),
+            (#line, pos: minPos, forwardY: false, lower: nil, upper: .full),
+            (#line, pos: fullPos, forwardY: true, lower: .full, upper: nil),
+            (#line, pos: fullPos, forwardY: false, lower: nil,  upper: .full),
+            (#line, pos: maxPos, forwardY: true, lower: .full, upper: nil),
+            (#line, pos: maxPos, forwardY: false, lower: .full, upper: nil),
+            ])
+    }
+
+    func test_updateInteractiveEdgeConstraint() {
+        fpc.showForTest()
+        fpc.move(to: .full, animated: false)
+
+        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.state)
+        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.state) // Should be ignore
+
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
+
+        var next: CGFloat
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: -100.0,
+                                                                        overflow: false,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: 100.0,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos + 100.0)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: tipPos - fullPos,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, tipPos)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: tipPos - fullPos + 100.0,
+                                                                        overflow: false,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, tipPos)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: tipPos - fullPos + 100.0,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, tipPos + 100.0)
+
+        fpc.floatingPanel.layoutAdapter.endInteraction(at: fpc.state)
+    }
+
+    func test_updateInteractiveEdgeConstraint_bottomEdge() {
+        fpc.layout = FloatingPanelTop2BottomTestLayout()
+        fpc.showForTest()
+        fpc.move(to: .tip, animated: false)
+        XCTAssertEqual(fpc.surfaceView.frame, CGRect(x: 0.0, y: -667.0 + 60.0, width: 375.0, height: 667))
+        XCTAssertEqual(fpc.surfaceView.containerView.frame, CGRect(x: 0.0, y: -667.0,
+                                                                   width: 375.0, height: 667 * 2.0))
+
+        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.state)
+        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.state) // Should be ignore
+
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.interactionConstraint?.constant, 60.0)
+
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
+
+        var pre: CGFloat
+        var next: CGFloat
+        pre = fpc.surfaceLocation.y
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: -100.0,
+                                                                        overflow: false,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, pre)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: 100.0,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, tipPos + 100.0)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: fullPos - tipPos,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: fullPos - tipPos + 100,
+                                                                        overflow: false,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: fullPos - tipPos + 100,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos + 100.0)
+
+        fpc.floatingPanel.layoutAdapter.endInteraction(at: fpc.state)
+    }
+
+    func test_updateInteractiveEdgeConstraintWithHidden() {
+        class FloatingPanelLayout2Positions: FloatingPanelLayout {
+            var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring]  {
+                return [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: 18.0, edge: .bottom, referenceGuide: .safeArea),
+                    .hidden: FloatingPanelLayoutAnchor(absoluteInset: 0, edge: .bottom, referenceGuide: .superview),
+                ]
+            }
+            let initialState: FloatingPanelState = .hidden
+            let position: FloatingPanelPosition = .bottom
+        }
+        fpc.layout = FloatingPanelLayout2Positions()
+        fpc.showForTest()
+        fpc.move(to: .full, animated: false)
+
+        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.state)
+
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let hiddenPos = fpc.surfaceLocation(for: .hidden).y
+
+        var next: CGFloat
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: -100.0,
+                                                                        overflow: false,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: -100.0,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos - 100.0)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: hiddenPos - fullPos + 100.0,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, hiddenPos + 100.0)
+
+        fpc.floatingPanel.layoutAdapter.endInteraction(at: fpc.state)
+    }
+
+    func test_updateInteractiveEdgeConstraintWithHidden_bottomEdge() {
+        class FloatingPanelLayout2Positions: FloatingPanelLayout {
+            var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring]  {
+                [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: 18.0, edge: .bottom, referenceGuide: .safeArea),
+                    .hidden: FloatingPanelLayoutAnchor(absoluteInset: 0, edge: .top, referenceGuide: .superview),
+                ]
+            }
+            let initialState: FloatingPanelState = .hidden
+            let position: FloatingPanelPosition = .top
+        }
+        fpc.layout = FloatingPanelLayout2Positions()
+        fpc.showForTest()
+        fpc.move(to: .full, animated: false)
+
+        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.state)
+
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let hiddenPos = fpc.surfaceLocation(for: .hidden).y
+
+        var next: CGFloat
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: 100.0,
+                                                                        overflow: false,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: 100.0,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos + 100.0)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: hiddenPos - fullPos + 100.0,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, hiddenPos + 100.0)
+
+        fpc.floatingPanel.layoutAdapter.endInteraction(at: fpc.state)
+    }
+
+    func test_updateInteractiveTopConstraintWithMinusInsets() {
+        class FloatingPanelLayoutMinusInsets: FloatingPanelLayout {
+            var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring]  {
+                [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: -200, edge: .top, referenceGuide: .safeArea),
+                    .tip: FloatingPanelLayoutAnchor(absoluteInset: -200, edge: .bottom, referenceGuide: .safeArea),
+                ]
+            }
+            let initialState: FloatingPanelState = .full
+            let position: FloatingPanelPosition = .bottom
+        }
+        fpc.layout = FloatingPanelLayoutMinusInsets()
+        fpc.showForTest()
+        fpc.floatingPanel.layoutAdapter.startInteraction(at: fpc.state)
+
+        let fullPos = fpc.surfaceLocation(for: .full).y
+        let tipPos = fpc.surfaceLocation(for: .tip).y
+
+        var next: CGFloat
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: -100.0,
+                                                                        overflow: false,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: -100.0,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, fullPos - 100)
+
+        fpc.floatingPanel.layoutAdapter.updateInteractiveEdgeConstraint(diff: tipPos - fullPos + 100.0,
+                                                                        overflow: true,
+                                                                        allowsRubberBanding: fpc.floatingPanel.behaviorAdapter.allowsRubberBanding(for:))
+        next = fpc.surfaceLocation.y
+        XCTAssertEqual(next, tipPos + 100)
+
+        fpc.floatingPanel.layoutAdapter.endInteraction(at: fpc.state)
+    }
+
+    func test_surfaceLocation() {
+        fpc = CustomSafeAreaFloatingPanelController()
+        fpc.loadViewIfNeeded()
+        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
+
+        class MyFloatingPanelFullLayout: FloatingPanelTestLayout {}
+        class MyFloatingPanelSafeAreaLayout: FloatingPanelTestLayout {
+            override var referenceGuide: FloatingPanelLayoutReferenceGuide {
+                return .safeArea
+            }
+        }
+
+        let myLayout = MyFloatingPanelFullLayout()
+        fpc.layout = myLayout
+        fpc.showForTest()
+
+        let bounds = fpc.view!.bounds
+        XCTAssertEqual(fpc.layout.anchors.filter({ $0.value.referenceGuide != .superview }).count, 0)
+        XCTAssertEqual(fpc.surfaceLocation(for: .full).y, myLayout.fullInset)
+        XCTAssertEqual(fpc.surfaceLocation(for: .half).y, bounds.height - myLayout.halfInset)
+        XCTAssertEqual(fpc.surfaceLocation(for: .tip).y, bounds.height - myLayout.tipInset)
+        XCTAssertEqual(fpc.surfaceLocation(for: .hidden).y, bounds.height + 100.0)
+
+        fpc.layout = MyFloatingPanelSafeAreaLayout()
+
+        XCTAssertEqual(fpc.layout.anchors.filter({ $0.value.referenceGuide != .safeArea }).count, 0)
+        XCTAssertEqual(fpc.surfaceLocation(for: .full).y, myLayout.fullInset + fpc.fp_safeAreaInsets.top)
+        XCTAssertEqual(fpc.surfaceLocation(for: .half).y, bounds.height - myLayout.halfInset + fpc.fp_safeAreaInsets.bottom)
+        XCTAssertEqual(fpc.surfaceLocation(for: .tip).y, bounds.height - myLayout.tipInset +  fpc.fp_safeAreaInsets.bottom)
+        XCTAssertEqual(fpc.surfaceLocation(for: .hidden).y, bounds.height + 100.0)
+    }
+
+    func test_surfaceLocation_bottomEdge() {
+        fpc = CustomSafeAreaFloatingPanelController()
+        fpc.loadViewIfNeeded()
+        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
+
+        class MyFloatingPanelFullLayout: FloatingPanelTop2BottomTestLayout { }
+        class MyFloatingPanelSafeAreaLayout: FloatingPanelTop2BottomTestLayout {
+            override var referenceGuide: FloatingPanelLayoutReferenceGuide {
+                return .safeArea
+            }
+        }
+        let myLayout = MyFloatingPanelFullLayout()
+        fpc.layout = myLayout
+        fpc.showForTest()
+
+        let bounds = fpc.view!.bounds
+        XCTAssertEqual(fpc.layout.anchors.filter({ $0.value.referenceGuide != .superview }).count, 0)
+        XCTAssertEqual(fpc.surfaceLocation(for: .full).y, bounds.height - myLayout.fullInset)
+        XCTAssertEqual(fpc.surfaceLocation(for: .half).y, myLayout.halfInset)
+        XCTAssertEqual(fpc.surfaceLocation(for: .tip).y,  myLayout.tipInset)
+        XCTAssertEqual(fpc.surfaceLocation(for: .hidden).y, -100.0)
+
+
+        fpc.layout = MyFloatingPanelSafeAreaLayout()
+
+        XCTAssertEqual(fpc.layout.anchors.filter({ $0.value.referenceGuide != .safeArea }).count, 0)
+        XCTAssertEqual(fpc.surfaceLocation(for: .full).y, bounds.height - myLayout.fullInset + fpc.fp_safeAreaInsets.bottom)
+        XCTAssertEqual(fpc.surfaceLocation(for: .half).y, myLayout.halfInset + fpc.fp_safeAreaInsets.top)
+        XCTAssertEqual(fpc.surfaceLocation(for: .tip).y, myLayout.tipInset + fpc.fp_safeAreaInsets.top)
+        XCTAssertEqual(fpc.surfaceLocation(for: .hidden).y, -100.0)
+    }
+
+    func test_layoutAnchor_topPosition() {
+        let position: FloatingPanelPosition = .top
+        fpc = CustomSafeAreaFloatingPanelController()
+        fpc.loadViewIfNeeded()
+        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
+
+        for prop in [
+            // from top edge
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .top, referenceGuide: .safeArea),
+             result: (#line, constant: 0.0, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.topAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 100.0, edge: .top, referenceGuide: .safeArea),
+             result: (#line, constant: 100.0, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.topAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .top, referenceGuide: .superview),
+             result: (#line, constant: 0.0, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.view.topAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 100.0, edge: .top, referenceGuide: .superview),
+             result: (#line, constant: 100.0, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.view.topAnchor)),
+            // from bottom edge
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .bottom, referenceGuide: .safeArea),
+             result: (#line, constant: 0.0, firstAnchor: fpc.fp_safeAreaLayoutGuide.bottomAnchor, secondAnchor: fpc.surfaceView.bottomAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 100.0, edge: .bottom, referenceGuide: .safeArea),
+             result: (#line, constant: 100.0, firstAnchor: fpc.fp_safeAreaLayoutGuide.bottomAnchor, secondAnchor: fpc.surfaceView.bottomAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .bottom, referenceGuide: .superview),
+             result: (#line, constant: 0.0, firstAnchor: fpc.view.bottomAnchor, secondAnchor: fpc.surfaceView.bottomAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 100.0, edge: .bottom, referenceGuide: .superview),
+             result: (#line, constant: 100.0, firstAnchor: fpc.view.bottomAnchor, secondAnchor: fpc.surfaceView.bottomAnchor)),
+            ] {
+                let c = prop.anchor.layoutConstraints(fpc, for: position)[0]
+                XCTAssertEqual(c.constant, CGFloat(prop.result.constant), line: UInt(prop.result.0))
+                XCTAssertEqual(c.firstAnchor, prop.result.firstAnchor, line: UInt(prop.result.0))
+                XCTAssertEqual(c.secondAnchor, prop.result.secondAnchor, line: UInt(prop.result.0))
+        }
+
+        // fractional
+        for prop in [
+            // from top edge
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.0, edge: .top, referenceGuide: .safeArea),
+             result: (#line, multiplier: 1.0, secondAnchor: nil)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .top, referenceGuide: .safeArea),
+             result: (#line, multiplier: 0.5, secondAnchor: fpc.fp_safeAreaLayoutGuide.heightAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.0, edge: .top, referenceGuide: .superview),
+             result: (#line, multiplier: 1.0, secondAnchor: nil)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .top, referenceGuide: .superview),
+             result: (#line, multiplier: 0.5, secondAnchor: fpc.view.heightAnchor)),
+
+            // from bottom edge
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.0, edge: .bottom, referenceGuide: .safeArea),
+             result: (#line, multiplier: 1.0, secondAnchor: nil)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
+             result: (#line, multiplier: 0.5, secondAnchor: fpc.fp_safeAreaLayoutGuide.heightAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.0, edge: .bottom, referenceGuide: .superview),
+             result: (#line, multiplier: 1.0, secondAnchor: nil)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .superview),
+             result: (#line, multiplier: 0.5, secondAnchor: fpc.view.heightAnchor)),
+            ] {
+                let c = prop.anchor.layoutConstraints(fpc, for: position)[0]
+                XCTAssertEqual(c.multiplier, CGFloat(prop.result.multiplier), line: UInt(prop.result.0))
+                XCTAssertTrue(c.firstAnchor is NSLayoutAnchor<NSLayoutDimension>, line: UInt(prop.result.0))
+                // On iOS 10, `c.secondAnchor` can't be equal object to `prop.result.secondAnchor`
+                // because there is no safe area  on iOS 10 and `fp_safeAreaLayoutGuide` emulates it.
+                if #available(iOS 11, *) {
+                    XCTAssertEqual(c.secondAnchor, prop.result.secondAnchor, line: UInt(prop.result.0))
+                }
+                print(c)
+        }
+    }
+    func test_layoutAnchor_bottomPosition() {
+        let position: FloatingPanelPosition = .bottom
+
+        fpc = CustomSafeAreaFloatingPanelController()
+        fpc.loadViewIfNeeded()
+        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
+
+        for prop in [
+            // from top edge
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .top, referenceGuide: .safeArea),
+             result: (#line, constant: 0.0, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.topAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 100.0, edge: .top, referenceGuide: .safeArea),
+             result: (#line, constant: 100.0, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.topAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .top, referenceGuide: .superview),
+             result: (#line, constant: 0.0, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.view.topAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 100.0, edge: .top, referenceGuide: .superview),
+             result: (#line, constant: 100.0, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.view.topAnchor)),
+
+            // from bottom edge
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .bottom, referenceGuide: .safeArea),
+             result: (#line, constant: 0.0, firstAnchor: fpc.fp_safeAreaLayoutGuide.bottomAnchor, secondAnchor: fpc.surfaceView.topAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 100.0, edge: .bottom, referenceGuide: .safeArea),
+             result: (#line, constant: 100.0, firstAnchor: fpc.fp_safeAreaLayoutGuide.bottomAnchor, secondAnchor: fpc.surfaceView.topAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .bottom, referenceGuide: .superview),
+             result: (#line, constant: 0.0, firstAnchor: fpc.view.bottomAnchor, secondAnchor: fpc.surfaceView.topAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(absoluteInset: 100.0, edge: .bottom, referenceGuide: .superview),
+             result: (#line, constant: 100.0, firstAnchor: fpc.view.bottomAnchor, secondAnchor: fpc.surfaceView.topAnchor)),
+            ] {
+                let c = prop.anchor.layoutConstraints(fpc, for: position)[0]
+                XCTAssertEqual(c.constant, CGFloat(prop.result.constant), line: UInt(prop.result.0))
+                XCTAssertEqual(c.firstAnchor, prop.result.firstAnchor, line: UInt(prop.result.0))
+                XCTAssertEqual(c.secondAnchor, prop.result.secondAnchor, line: UInt(prop.result.0))
+        }
+
+        // fractional
+        for prop in [
+            // from top edge
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.0, edge: .top, referenceGuide: .safeArea),
+             result: (#line, multiplier: 1.0, secondAnchor: nil)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .top, referenceGuide: .safeArea),
+             result: (#line, multiplier: 0.5, secondAnchor: fpc.fp_safeAreaLayoutGuide.heightAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.0, edge: .top, referenceGuide: .superview),
+             result: (#line, multiplier: 1.0, secondAnchor: nil)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .top, referenceGuide: .superview),
+             result: (#line, multiplier: 0.5, secondAnchor: fpc.view.heightAnchor)),
+
+            // from bottom edge
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.0, edge: .bottom, referenceGuide: .safeArea),
+             result: (#line, multiplier: 1.0, secondAnchor: nil)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
+             result: (#line, multiplier: 0.5, secondAnchor: fpc.fp_safeAreaLayoutGuide.heightAnchor)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.0, edge: .bottom, referenceGuide: .superview),
+             result: (#line, multiplier: 1.0, secondAnchor: nil)),
+            (anchor: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .superview),
+             result: (#line, multiplier: 0.5, secondAnchor: fpc.view.heightAnchor)),
+            ] {
+                let c = prop.anchor.layoutConstraints(fpc, for: position)[0]
+                XCTAssertEqual(c.multiplier, CGFloat(prop.result.multiplier), line: UInt(prop.result.0))
+                XCTAssertTrue(c.firstAnchor is NSLayoutAnchor<NSLayoutDimension>, line: UInt(prop.result.0))
+                // On iOS 10, `c.secondAnchor` can't be equal object to `prop.result.secondAnchor`
+                // because there is no safe area  on iOS 10 and `fp_safeAreaLayoutGuide` emulates it.
+                if #available(iOS 11, *) {
+                    XCTAssertEqual(c.secondAnchor, prop.result.secondAnchor, line: UInt(prop.result.0))
+                }
+                print(c)
+        }
+    }
+
+    func test_intrinsicLayoutAnchor_topPosition() {
+        class ContentViewController: UIViewController {
+            class IntrinsicView: UIView {
+                override var intrinsicContentSize: CGSize {
+                    return CGSize(width: UIView.noIntrinsicMetric, height: 420)
+                }
+            }
+            override func loadView() {
+                self.view = IntrinsicView()
+            }
+        }
+        let position: FloatingPanelPosition = .top
+
+        fpc = CustomSafeAreaFloatingPanelController()
+        fpc.loadViewIfNeeded()
+        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
+        let contentVC = ContentViewController()
+        contentVC.loadViewIfNeeded()
+        fpc.set(contentViewController: contentVC)
+
+        for prop in [
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 0.0, referenceGuide: .safeArea),
+             result: (#line, constant: 420, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.topAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 42.0, referenceGuide: .safeArea),
+             result: (#line, constant: 420 - 42, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.topAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 0.0, referenceGuide: .superview),
+             result: (#line, constant: 420, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.view.topAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 42.0, referenceGuide: .superview),
+             result: (#line, constant: 420 - 42, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.view.topAnchor)),
+
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.0, referenceGuide: .safeArea),
+             result: (#line, constant: 420, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.topAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.5, referenceGuide: .safeArea),
+             result: (#line, constant: 210, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.topAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 1.0, referenceGuide: .safeArea),
+             result: (#line, constant: 0, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.topAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.0, referenceGuide: .superview),
+             result: (#line, constant: 420, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.view.topAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.5, referenceGuide: .superview),
+             result: (#line, constant: 210, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.view.topAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 1.0, referenceGuide: .superview),
+             result: (#line, constant: 0, firstAnchor: fpc.surfaceView.bottomAnchor, secondAnchor: fpc.view.topAnchor)),
+            ] {
+                let c = prop.anchor.layoutConstraints(fpc, for: position)[0]
+                XCTAssertEqual(c.constant, CGFloat(prop.result.constant), line: UInt(prop.result.0))
+                XCTAssertEqual(c.firstAnchor, prop.result.firstAnchor, line: UInt(prop.result.0))
+                XCTAssertEqual(c.secondAnchor, prop.result.secondAnchor, line: UInt(prop.result.0))
+        }
+    }
+
+    func test_intrinsicLayoutAnchor_bottomPosition() {
+        class ContentViewController: UIViewController {
+            class IntrinsicView: UIView {
+                override var intrinsicContentSize: CGSize {
+                    return CGSize(width: UIView.noIntrinsicMetric, height: 420)
+                }
+            }
+            override func loadView() {
+                self.view = IntrinsicView()
+            }
+        }
+        let position: FloatingPanelPosition = .bottom
+
+        fpc = CustomSafeAreaFloatingPanelController()
+        fpc.loadViewIfNeeded()
+        fpc.view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
+        let contentVC = ContentViewController()
+        contentVC.loadViewIfNeeded()
+        fpc.set(contentViewController: contentVC)
+
+        for prop in [
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 0.0, referenceGuide: .safeArea),
+             result: (#line, constant: -420, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.bottomAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 42.0, referenceGuide: .safeArea),
+             result: (#line, constant: -420 + 42, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.bottomAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 0.0, referenceGuide: .superview),
+             result: (#line, constant: -420, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.view.bottomAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 42.0, referenceGuide: .superview),
+             result: (#line, constant: -420 + 42, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.view.bottomAnchor)),
+
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.0, referenceGuide: .safeArea),
+             result: (#line, constant: -420, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.bottomAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.5, referenceGuide: .safeArea),
+             result: (#line, constant: -210, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.bottomAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 1.0, referenceGuide: .safeArea),
+             result: (#line, constant: 0, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.fp_safeAreaLayoutGuide.bottomAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.0, referenceGuide: .superview),
+             result: (#line, constant: -420, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.view.bottomAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.5, referenceGuide: .superview),
+             result: (#line, constant: -210, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.view.bottomAnchor)),
+            (anchor: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 1.0, referenceGuide: .superview),
+             result: (#line, constant: 0, firstAnchor: fpc.surfaceView.topAnchor, secondAnchor: fpc.view.bottomAnchor)),
+            ] {
+                let c = prop.anchor.layoutConstraints(fpc, for: position)[0]
+                XCTAssertEqual(c.constant, CGFloat(prop.result.constant), line: UInt(prop.result.0))
+                XCTAssertEqual(c.firstAnchor, prop.result.firstAnchor, line: UInt(prop.result.0))
+                XCTAssertEqual(c.secondAnchor, prop.result.secondAnchor, line: UInt(prop.result.0))
+        }
+    }
+}
+
+private typealias LayoutSegmentTestParameter = (UInt, pos: CGFloat, forwardY: Bool, lower: FloatingPanelState?, upper: FloatingPanelState?)
+private func assertLayoutSegment(_ floatingPanel: Core, with params: [LayoutSegmentTestParameter]) {
+    params.forEach { (line, pos, forwardY, lowr, upper) in
+        let segment = floatingPanel.layoutAdapter.segment(at: pos, forward: forwardY)
+        XCTAssertEqual(segment.lower, lowr, line: line)
+        XCTAssertEqual(segment.upper, upper, line: line)
+    }
+}
+
+private class CustomSafeAreaFloatingPanelController: FloatingPanelController {
+    override var fp_safeAreaInsets: UIEdgeInsets {
+        return UIEdgeInsets(top: 64.0, left: 0.0, bottom: 0.0, right: 34.0)
+    }
+}

Tests/StateTests.swift

@@ -0,0 +1,24 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import XCTest
+@testable import FloatingPanel
+
+class StateTests: XCTestCase {
+    override func setUp() { }
+    override func tearDown() { }
+
+    func test_nextAndPre() {
+        var positions: [FloatingPanelState]
+        positions = [.full, .half, .tip, .hidden]
+        XCTAssertEqual(FloatingPanelState.full.next(in: positions),  .half)
+        XCTAssertEqual(FloatingPanelState.full.pre(in: positions),  .full)
+        XCTAssertEqual(FloatingPanelState.hidden.next(in: positions), .hidden)
+        XCTAssertEqual(FloatingPanelState.hidden.pre(in: positions), .tip)
+
+        positions = [.full, .hidden]
+        XCTAssertEqual(FloatingPanelState.full.next(in: positions),  .hidden)
+        XCTAssertEqual(FloatingPanelState.full.pre(in: positions),  .full)
+        XCTAssertEqual(FloatingPanelState.hidden.next(in: positions), .hidden)
+        XCTAssertEqual(FloatingPanelState.hidden.pre(in: positions), .full)
+    }
+}

Tests/SurfaceViewTests.swift

@@ -0,0 +1,230 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import XCTest
+@testable import FloatingPanel
+
+class SurfaceViewTests: XCTestCase {
+    override func setUp() {}
+    override func tearDown() {}
+
+    func test_surfaceView() {
+        let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+        XCTAssertTrue(SurfaceView.requiresConstraintBasedLayout)
+        XCTAssert(surface.contentView == nil)
+        surface.layoutIfNeeded()
+        XCTAssert(surface.grabberHandle.frame.minY == 6.0)
+        XCTAssert(surface.grabberHandle.frame.width == surface.grabberHandleSize.width)
+        XCTAssert(surface.grabberHandle.frame.height == surface.grabberHandleSize.height)
+        surface.backgroundColor = .red
+        surface.layoutIfNeeded()
+        XCTAssert(surface.backgroundColor == surface.containerView.backgroundColor)
+    }
+
+    func test_surfaceView_containerView() {
+        XCTContext.runActivity(named: "Bottom sheet") { _ in
+            let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+            XCTAssertNil(surface.contentView)
+            surface.layoutIfNeeded()
+
+            let height = surface.bounds.height * 2
+            surface.containerOverflow = height
+            surface.setNeedsLayout()
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.containerView.frame, CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0 * 3))
+        }
+
+        XCTContext.runActivity(named: "Top sheet") { _ in
+            let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+            surface.position = .top
+            XCTAssertNil(surface.contentView)
+            surface.layoutIfNeeded()
+
+            let height = surface.bounds.height * 2
+            surface.containerOverflow = height
+            surface.setNeedsLayout()
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.containerView.frame, CGRect(x: 0.0, y: -height, width: 320.0, height: 480.0 * 3))
+        }
+    }
+
+    func test_surfaceView_contentView() {
+        XCTContext.runActivity(named: "Bottom sheet") { _ in
+            let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+            surface.layoutIfNeeded()
+
+            let contentView = UIView()
+            surface.set(contentView: contentView)
+
+            let height = surface.bounds.height * 2
+            surface.containerOverflow = height
+            surface.setNeedsLayout()
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.contentView?.frame ?? .zero, surface.bounds)
+        }
+
+        XCTContext.runActivity(named: "Top sheet") { _ in
+            let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+            surface.position = .top
+            surface.layoutIfNeeded()
+
+            let contentView = UIView()
+            surface.set(contentView: contentView)
+
+            let height = surface.bounds.height * 2
+            surface.containerOverflow = height
+            surface.setNeedsLayout()
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.containerView.frame, CGRect(x: 0.0, y: -height, width: 320.0, height: 480.0 * 3))
+            XCTAssertEqual(surface.convert(surface.contentView?.frame ?? .zero, from: surface.containerView),
+                           surface.bounds)
+        }
+    }
+
+
+    func test_surfaceView_grabberHandle() {
+        XCTContext.runActivity(named: "Bottom sheet") { _ in
+            let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+            XCTAssertNil(surface.contentView)
+            surface.layoutIfNeeded()
+
+            XCTAssertEqual(surface.grabberHandle.frame.minY,  6.0)
+            XCTAssertEqual(surface.grabberHandle.frame.width, surface.grabberHandleSize.width)
+            XCTAssertEqual(surface.grabberHandle.frame.height, surface.grabberHandleSize.height)
+
+            surface.grabberHandlePadding = 10.0
+            surface.grabberHandleSize = CGSize(width: 44.0, height: 12.0)
+            surface.setNeedsLayout()
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.grabberHandle.frame.minY,  surface.grabberHandlePadding)
+            XCTAssertEqual(surface.grabberHandle.frame.width, surface.grabberHandleSize.width)
+            XCTAssertEqual(surface.grabberHandle.frame.height, surface.grabberHandleSize.height)
+        }
+
+        XCTContext.runActivity(named: "Top sheet") { _ in
+            let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+            surface.position = .top
+            XCTAssertNil(surface.contentView)
+            surface.layoutIfNeeded()
+
+            XCTAssertEqual(surface.grabberHandle.frame.maxY, (surface.bounds.maxY - 6.0))
+            XCTAssertEqual(surface.grabberHandle.frame.width, surface.grabberHandleSize.width)
+            XCTAssertEqual(surface.grabberHandle.frame.height, surface.grabberHandleSize.height)
+
+            surface.grabberHandlePadding = 10.0
+            surface.setNeedsLayout()
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.grabberHandle.frame.maxY,  surface.bounds.maxY - surface.grabberHandlePadding)
+        }
+    }
+
+    func test_surfaceView_contentMargins() {
+        XCTContext.runActivity(named: "Top sheet") { _ in
+            let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+            surface.position = .top
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.containerView.frame, surface.bounds)
+            surface.containerMargins = UIEdgeInsets(top: 16.0, left: 16.0, bottom: 16.0, right: 16.0)
+            surface.setNeedsLayout()
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.containerView.frame, surface.bounds.inset(by: surface.containerMargins))
+        }
+        XCTContext.runActivity(named: "Bottom sheet") { _ in
+            let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.containerView.frame, surface.bounds)
+            surface.containerMargins = UIEdgeInsets(top: 16.0, left: 16.0, bottom: 16.0, right: 16.0)
+            surface.setNeedsLayout()
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.containerView.frame, surface.bounds.inset(by: surface.containerMargins))
+        }
+    }
+
+    func test_surfaceView_contentInsets() {
+        XCTContext.runActivity(named: "Top sheet") { _ in
+            let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+            surface.position = .top
+            let contentView = UIView()
+            surface.set(contentView: contentView)
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.contentView?.frame ?? .zero, surface.bounds)
+            surface.contentPadding = UIEdgeInsets(top: 16.0, left: 16.0, bottom: 16.0, right: 16.0)
+            surface.setNeedsLayout()
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.contentView?.frame ?? .zero, surface.bounds.inset(by: surface.contentPadding))
+        }
+        XCTContext.runActivity(named: "Bottom sheet") { _ in
+            let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+            let contentView = UIView()
+            surface.set(contentView: contentView)
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.contentView?.frame ?? .zero, surface.bounds)
+            surface.contentPadding = UIEdgeInsets(top: 16.0, left: 16.0, bottom: 16.0, right: 16.0)
+            surface.setNeedsLayout()
+            surface.layoutIfNeeded()
+            XCTAssertEqual(surface.contentView?.frame ?? .zero, surface.bounds.inset(by: surface.contentPadding))
+        }
+    }
+
+    func test_surfaceView_containerMargins_and_contentInsets() {
+        let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+        let contentView = UIView()
+        surface.set(contentView: contentView)
+        surface.layoutIfNeeded()
+        XCTAssertEqual(surface.contentView?.frame ?? .zero, surface.bounds)
+        surface.containerMargins = UIEdgeInsets(top: 16.0, left: 16.0, bottom: 16.0, right: 16.0)
+        surface.contentPadding = UIEdgeInsets(top: 16.0, left: 16.0, bottom: 16.0, right: 16.0)
+        surface.setNeedsLayout()
+        surface.layoutIfNeeded()
+        XCTAssertEqual(surface.containerView.frame, surface.bounds.inset(by: surface.containerMargins))
+        XCTAssertEqual(surface.contentView?.frame ?? .zero, surface.containerView.bounds.inset(by: surface.contentPadding))
+    }
+
+    func test_surfaceView_cornderRaduis() {
+        let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+        XCTAssert(surface.containerView.layer.cornerRadius == 0.0)
+        XCTAssert(surface.containerView.layer.masksToBounds == false)
+
+        let appearance = SurfaceAppearance()
+
+        appearance.cornerRadius = 10.0
+        surface.appearance = appearance
+        surface.layoutIfNeeded()
+        XCTAssert(surface.containerView.layer.cornerRadius == 10.0)
+        XCTAssert(surface.containerView.layer.masksToBounds == true)
+
+        surface.containerView.layer.cornerRadius = 12.0
+        surface.layoutIfNeeded()
+        XCTAssert(surface.containerView.layer.cornerRadius == 12.0)
+        XCTAssert(surface.containerView.layer.masksToBounds == true)
+
+        appearance.cornerRadius = 0.0
+        surface.appearance = appearance
+        surface.layoutIfNeeded()
+        XCTAssert(surface.containerView.layer.cornerRadius == 0.0)
+        XCTAssert(surface.containerView.layer.masksToBounds == false)
+
+        surface.containerView.layer.cornerRadius = 12.0 // Don't change it directly
+        XCTAssert(surface.containerView.layer.cornerRadius == 12.0)
+        XCTAssertFalse(surface.containerView.layer.masksToBounds == true)
+
+        surface.setNeedsLayout()
+        surface.layoutIfNeeded()
+        // Reset corner radius by the current appearance
+        XCTAssert(surface.containerView.layer.cornerRadius == 0.0)
+        XCTAssert(surface.containerView.layer.masksToBounds == false)
+
+    }
+
+    func test_surfaceView_border() {
+        let surface = SurfaceView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))
+        XCTAssert(surface.containerView.layer.borderWidth == 0.0)
+
+        let appearance = SurfaceAppearance()
+        appearance.borderColor = .red
+        appearance.borderWidth = 3.0
+        surface.appearance = appearance
+        surface.layoutIfNeeded()
+        XCTAssert(surface.containerView.layer.borderColor == UIColor.red.cgColor)
+        XCTAssert(surface.containerView.layer.borderWidth == 3.0)
+    }
+}

Tests/TestSupports.swift

@@ -0,0 +1,79 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import Foundation
+@testable import FloatingPanel
+
+func waitRunLoop(secs: TimeInterval = 0) {
+    RunLoop.main.run(until: Date(timeIntervalSinceNow: secs))
+}
+
+extension FloatingPanelController {
+    func showForTest() {
+        loadViewIfNeeded()
+        view.frame = CGRect(x: 0, y: 0, width: 375, height: 667)
+        show(animated: false, completion: nil)
+    }
+}
+
+class FloatingPanelTestDelegate: FloatingPanelControllerDelegate {
+    var position: FloatingPanelState = .hidden
+    var didMoveCallback: ((FloatingPanelController) -> Void)?
+    func floatingPanelDidChangePosition(_ vc: FloatingPanelController) {
+        position = vc.state
+    }
+    func floatingPanelDidMove(_ vc: FloatingPanelController) {
+        didMoveCallback?(vc)
+    }
+}
+
+class FloatingPanelTestLayout: FloatingPanelLayout {
+    let fullInset: CGFloat = 20.0
+    let halfInset: CGFloat = 250.0
+    let tipInset: CGFloat = 60.0
+
+    var initialState: FloatingPanelState {
+        return .half
+    }
+    var position: FloatingPanelPosition {
+        return .bottom
+    }
+    var referenceGuide: FloatingPanelLayoutReferenceGuide {
+        return .superview
+    }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: fullInset, edge: .top, referenceGuide: referenceGuide),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: halfInset, edge: .bottom, referenceGuide: referenceGuide),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: tipInset, edge: .bottom, referenceGuide: referenceGuide),
+        ]
+    }
+}
+
+class FloatingPanelTop2BottomTestLayout: FloatingPanelLayout {
+    let fullInset: CGFloat = 0.0
+    let halfInset: CGFloat = 250.0
+    let tipInset: CGFloat = 60.0
+
+    var initialState: FloatingPanelState {
+        return .half
+    }
+    var position: FloatingPanelPosition {
+        return .top
+    }
+    var referenceGuide: FloatingPanelLayoutReferenceGuide {
+        return .superview
+    }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: fullInset, edge: .bottom, referenceGuide: referenceGuide),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: halfInset, edge: .top, referenceGuide: referenceGuide),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: tipInset, edge: .top, referenceGuide: referenceGuide),
+        ]
+    }
+}
+
+class FloatingPanelProjectableBehavior: FloatingPanelBehavior {
+    func shouldProjectMomentum(_ fpc: FloatingPanelController, to proposedTargetPosition: FloatingPanelState) -> Bool {
+        return true
+    }
+}

Tests/TestingApp/AppDelegate.swift

@@ -1,7 +1,4 @@
-//
-//  Created by Shin Yamamoto on 2018/11/01.
-//  Copyright © 2018 Shin Yamamoto. All rights reserved.
-//
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
 
 import UIKit
 @UIApplicationMain

Tests/UtilTests.swift

@@ -0,0 +1,12 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import XCTest
+@testable import FloatingPanel
+
+class UtilTests: XCTestCase {
+    func test_displayTrunc() {
+        XCTAssertEqual(displayTrunc(333.222, by: 3), 333.3333333333333)
+        XCTAssertNotEqual(displayTrunc(333.5, by: 3), 333.66666666666674)
+        XCTAssertTrue(displayEqual(333.5, 333.66666666666674, by: 3))
+    }
+}