Version 2.1.0

* Fix the detail vc layout in Maps sample
* Deactivate search bar when the detail vc shows in Maps sample

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: SCENEE

.gitignore

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

.swiftformat

@@ -1,3 +1,3 @@
---header "// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license."
+--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
@@ -15,58 +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 -scheme SamplesObjC -sdk iphonesimulator clean build
-    osx_image: xcode11
+  - 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/Base.lproj/Main.storyboard

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<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">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="17506" 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="16087"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="17505"/>
         <capability name="Safe area layout guides" minToolsVersion="9.0"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
@@ -25,9 +25,10 @@
                                     <rect key="frame" x="0.0" y="0.0" width="375" height="44"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                 </view>
-                                <blurEffect style="light"/>
+                                <blurEffect style="prominent"/>
                             </visualEffectView>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/>
                         <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
                         <constraints>
                             <constraint firstItem="5Jw-n2-Cpw" firstAttribute="trailing" secondItem="8bC-Xf-vdC" secondAttribute="trailing" id="1Fg-Be-qfh"/>
@@ -39,7 +40,6 @@
                             <constraint firstItem="6Tk-OE-BBY" firstAttribute="top" secondItem="d9i-3g-8Ja" secondAttribute="bottom" id="Y1G-hr-aEX"/>
                             <constraint firstItem="d9i-3g-8Ja" firstAttribute="leading" secondItem="6Tk-OE-BBY" secondAttribute="leading" id="diB-Ij-HN3"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/>
                     </view>
                     <connections>
                         <outlet property="mapView" destination="5Jw-n2-Cpw" id="WVC-rU-mLe"/>
@@ -230,9 +230,10 @@
                                         <constraint firstItem="Zcj-SE-gb8" firstAttribute="leading" secondItem="ED1-gT-FBj" secondAttribute="leading" id="wMb-L2-Z0W"/>
                                     </constraints>
                                 </view>
-                                <blurEffect style="extraLight"/>
+                                <blurEffect style="prominent"/>
                             </visualEffectView>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="G74-X7-Za8"/>
                         <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"/>
@@ -240,7 +241,6 @@
                             <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>
-                        <viewLayoutGuide key="safeArea" id="G74-X7-Za8"/>
                     </view>
                     <connections>
                         <outlet property="searchBar" destination="Zcj-SE-gb8" id="BH7-Gy-RG5"/>
@@ -262,7 +262,7 @@
                         <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"/>
+                                <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="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"/>
@@ -282,8 +282,8 @@
                                 <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"/>
+                        <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                     </view>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="EDp-D2-xcT" userLabel="First Responder" customClass="UIResponder" sceneMemberID="firstResponder"/>

Examples/Maps/Maps/SearchViewController.swift

@@ -21,6 +21,9 @@ extension ViewController: UITableViewDelegate {
 
     func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
         tableView.deselectRow(at: indexPath, animated: true)
+
+        deactivate(searchBar: searchVC.searchBar)
+
         // Show a detail panel
         switch indexPath.row {
         case 0:

Examples/Maps/Maps/ViewController.swift

@@ -114,19 +114,27 @@ extension FloatingPanelController {
 // MARK: - UISearchBarDelegate
 
 extension ViewController: UISearchBarDelegate {
-    func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
+    func activate(searchBar: UISearchBar) {
+        searchBar.showsCancelButton = true
+        searchVC.showHeader(animated: true)
+        searchVC.tableView.alpha = 1.0
+        detailVC.dismiss(animated: true, completion: nil)
+    }
+    func deactivate(searchBar: UISearchBar) {
         searchBar.resignFirstResponder()
         searchBar.showsCancelButton  = false
         searchVC.hideHeader(animated: true)
-        UIView.animate(withDuration: 0.25) { [weak self] in
-            self?.fpc.move(to: .half, animated: false)
+    }
+
+    func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
+        deactivate(searchBar: searchBar)
+        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
+        activate(searchBar: searchBar)
         UIView.animate(withDuration: 0.25) { [weak self] in
             self?.fpc.move(to: .full, animated: false)
         }

Examples/Samples/Sources/Assets.xcassets/Contents.json

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

Examples/Samples/Sources/Assets.xcassets/IMG_0003.imageset/Contents.json

@@ -0,0 +1,12 @@
+{
+  "images" : [
+    {
+      "filename" : "IMG_0003.jpg",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

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

@@ -1,10 +1,12 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<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="RoN-h0-uBD">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="17506" 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="16087"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="17505"/>
         <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="Stack View standard spacing" minToolsVersion="9.0"/>
+        <capability name="System colors in document resources" minToolsVersion="11.0"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
     <scenes>
@@ -44,7 +46,7 @@
                                             <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 +58,7 @@
                                 </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 +66,6 @@
                             <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 +90,76 @@
                         <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 +180,7 @@
                         <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 +189,13 @@
                                 </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 +211,7 @@
                         <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 +220,13 @@
                                 </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 +242,7 @@
                         <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 +251,13 @@
                                 </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 +274,19 @@
                         <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>
@@ -283,6 +294,71 @@
             </objects>
             <point key="canvasLocation" x="2753" y="734"/>
         </scene>
+        <!--Image View Controller-->
+        <scene sceneID="NAI-Rh-ZQ6">
+            <objects>
+                <viewController storyboardIdentifier="ImageViewController" id="VWY-cF-RoY" customClass="ImageViewController" customModule="Samples" sceneMemberID="viewController">
+                    <view key="view" contentMode="scaleToFill" id="dAf-gD-ghB">
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="778"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" translatesAutoresizingMaskIntoConstraints="NO" id="Gs4-S6-Goh">
+                                <rect key="frame" x="0.0" y="0.0" width="375" height="778"/>
+                                <subviews>
+                                    <view contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="t7x-eG-MKh">
+                                        <rect key="frame" x="0.0" y="0.0" width="375" height="49"/>
+                                        <color key="backgroundColor" systemColor="systemOrangeColor"/>
+                                        <constraints>
+                                            <constraint firstAttribute="height" constant="49" id="DmG-pt-gij"/>
+                                        </constraints>
+                                    </view>
+                                    <scrollView clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" alwaysBounceHorizontal="YES" showsHorizontalScrollIndicator="NO" showsVerticalScrollIndicator="NO" translatesAutoresizingMaskIntoConstraints="NO" id="kRA-qy-GpJ">
+                                        <rect key="frame" x="0.0" y="49" width="375" height="680"/>
+                                        <subviews>
+                                            <imageView clipsSubviews="YES" userInteractionEnabled="NO" contentMode="scaleAspectFill" horizontalHuggingPriority="1000" verticalHuggingPriority="1000" image="IMG_0003" translatesAutoresizingMaskIntoConstraints="NO" id="rGf-jW-WNf">
+                                                <rect key="frame" x="0.0" y="0.0" width="750" height="501"/>
+                                                <color key="backgroundColor" systemColor="systemPurpleColor"/>
+                                            </imageView>
+                                        </subviews>
+                                        <color key="backgroundColor" red="0.0078431372550000003" green="0.72156862749999995" blue="0.45882352939999999" alpha="1" colorSpace="calibratedRGB"/>
+                                        <constraints>
+                                            <constraint firstAttribute="trailing" secondItem="rGf-jW-WNf" secondAttribute="trailing" id="472-Be-cUl"/>
+                                            <constraint firstAttribute="bottom" secondItem="rGf-jW-WNf" secondAttribute="bottom" id="ncs-tN-3Wx"/>
+                                            <constraint firstItem="rGf-jW-WNf" firstAttribute="leading" secondItem="kRA-qy-GpJ" secondAttribute="leading" id="rlv-5Y-utR"/>
+                                            <constraint firstItem="rGf-jW-WNf" firstAttribute="top" secondItem="kRA-qy-GpJ" secondAttribute="top" id="zum-Zl-Wzz"/>
+                                        </constraints>
+                                    </scrollView>
+                                    <view contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="SEa-7Y-wa9">
+                                        <rect key="frame" x="0.0" y="729" width="375" height="49"/>
+                                        <color key="backgroundColor" systemColor="systemTealColor"/>
+                                        <constraints>
+                                            <constraint firstAttribute="height" constant="49" id="3mS-zi-8BP"/>
+                                        </constraints>
+                                    </view>
+                                </subviews>
+                            </stackView>
+                        </subviews>
+                        <viewLayoutGuide key="safeArea" id="hCg-v5-nJs"/>
+                        <color key="backgroundColor" systemColor="systemBackgroundColor"/>
+                        <constraints>
+                            <constraint firstAttribute="trailing" secondItem="Gs4-S6-Goh" secondAttribute="trailing" id="6z7-Md-pxr"/>
+                            <constraint firstAttribute="bottom" secondItem="Gs4-S6-Goh" secondAttribute="bottom" id="PcQ-bu-yT3"/>
+                            <constraint firstItem="Gs4-S6-Goh" firstAttribute="top" secondItem="dAf-gD-ghB" secondAttribute="top" id="zGx-Wd-hjz"/>
+                            <constraint firstItem="Gs4-S6-Goh" firstAttribute="leading" secondItem="dAf-gD-ghB" secondAttribute="leading" id="zxi-Ty-U7L"/>
+                        </constraints>
+                    </view>
+                    <size key="freeformSize" width="375" height="778"/>
+                    <connections>
+                        <outlet property="footerView" destination="SEa-7Y-wa9" id="Gzj-dP-YXl"/>
+                        <outlet property="headerView" destination="t7x-eG-MKh" id="njM-un-U8q"/>
+                        <outlet property="scrollView" destination="kRA-qy-GpJ" id="iWC-o4-APi"/>
+                        <outlet property="stackView" destination="Gs4-S6-Goh" id="f1D-bO-mjr"/>
+                    </connections>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="pnR-69-Ek4" userLabel="First Responder" customClass="UIResponder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="3388" y="734.48275862068965"/>
+        </scene>
         <!--Tab Bar View Controller-->
         <scene sceneID="nQ5-PV-qFw">
             <objects>
@@ -314,7 +390,7 @@
                                 <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 +400,35 @@
                             <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 +438,7 @@
                                 </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 +450,6 @@
                             <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 +542,7 @@
                                 </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 +551,6 @@
                             <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 +601,7 @@
                                 <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 +612,16 @@
                                 </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>
@@ -555,14 +631,14 @@
                             <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" spacing="22" translatesAutoresizingMaskIntoConstraints="NO" id="tP3-oJ-4EB">
                                 <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 +646,7 @@
                                             <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 +656,7 @@
                                 </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>
@@ -598,7 +675,6 @@
                             <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 +762,7 @@ 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 +770,6 @@ 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>
@@ -707,7 +783,27 @@ 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>
+    <resources>
+        <image name="IMG_0003" width="750" height="501"/>
+        <systemColor name="systemBackgroundColor">
+            <color white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
+        </systemColor>
+        <systemColor name="systemOrangeColor">
+            <color red="1" green="0.58431372549019611" blue="0.0" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+        </systemColor>
+        <systemColor name="systemPurpleColor">
+            <color red="0.68627450980392157" green="0.32156862745098042" blue="0.87058823529411766" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+        </systemColor>
+        <systemColor name="systemTealColor">
+            <color red="0.35294117647058826" green="0.78431372549019607" blue="0.98039215686274506" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+        </systemColor>
+    </resources>
 </document>

Examples/Samples/Sources/ViewController.swift

@@ -23,7 +23,9 @@ class SampleListViewController: UIViewController {
         case showContentInset
         case showContainerMargins
         case showNavigationController
-        case showBottomEdgeInteraction
+        case showTopPositionedPanel
+        case showAdaptivePanel
+        case showAdaptivePanelWithCustomGuide
 
         var name: String {
             switch self {
@@ -43,7 +45,9 @@ 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"
+            case .showTopPositionedPanel: return "Show Top Positioned Panel"
+            case .showAdaptivePanel: return "Show Adaptive Panel"
+            case .showAdaptivePanelWithCustomGuide: return "Show Adaptive Panel (Custom Layout Guide)"
             }
         }
 
@@ -65,7 +69,10 @@ class SampleListViewController: UIViewController {
             case .showContentInset: return nil
             case .showContainerMargins: return nil
             case .showNavigationController: return "RootNavigationController"
-            case .showBottomEdgeInteraction: return nil
+            case .showTopPositionedPanel: return nil
+            case .showAdaptivePanel,
+                 .showAdaptivePanelWithCustomGuide:
+                return "ImageViewController"
             }
         }
     }
@@ -142,6 +149,8 @@ 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
@@ -151,12 +160,10 @@ class SampleListViewController: UIViewController {
             }
         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
+        case .showTopPositionedPanel: // For debug
             let contentVC = UIViewController()
             contentVC.view.backgroundColor = .red
             mainPanelVC.set(contentViewController: contentVC)
@@ -184,6 +191,17 @@ class SampleListViewController: UIViewController {
                 rootVC.loadViewIfNeeded()
                 mainPanelVC.track(scrollView: rootVC.tableView)
             }
+        case let contentVC as ImageViewController:
+            if #available(iOS 11.0, *) {
+                let mode: ImageViewController.Mode = (currentMenu == .showAdaptivePanelWithCustomGuide) ? .withHeaderFooter : .onlyImage
+                let layoutGuide = contentVC.layoutGuideFor(mode: mode)
+                mainPanelVC.layout = ImageViewController.PanelLayout(targetGuide: layoutGuide)
+            } else {
+                mainPanelVC.layout = ImageViewController.PanelLayout(targetGuide: nil)
+            }
+            mainPanelVC.delegate = nil
+            mainPanelVC.isRemovalInteractionEnabled = true
+            mainPanelVC.track(scrollView: contentVC.scrollView)
         default:
             break
         }
@@ -208,18 +226,6 @@ 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 }
@@ -231,10 +237,7 @@ class SampleListViewController: UIViewController {
         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")
@@ -302,7 +305,7 @@ extension SampleListViewController: UITableViewDelegate {
             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, animated: true)
@@ -353,6 +356,7 @@ extension SampleListViewController: UITableViewDelegate {
             let appearance = SurfaceAppearance()
             appearance.cornerRadius = 38.5
             fpc.surfaceView.appearance = appearance
+            fpc.backdropView.dismissalTapGestureRecognizer.isEnabled = true
 
             fpc.isRemovalInteractionEnabled = true
 
@@ -433,8 +437,8 @@ extension SampleListViewController: FloatingPanelControllerDelegate {
         }
 
         switch currentMenu {
-        case .showBottomEdgeInteraction:
-            return BottomEdgeInteractionLayout()
+        case .showTopPositionedPanel:
+            return TopPositionedPanelLayout()
         case .showRemovablePanel:
             return newCollection.verticalSizeClass == .compact ? RemovablePanelLandscapeLayout() :  RemovablePanelLayout()
         case .showIntrinsicView:
@@ -480,7 +484,7 @@ extension SampleListViewController: UIGestureRecognizerDelegate {
 
 /**
  - 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 {
@@ -520,7 +524,7 @@ extension SampleListViewController: UIPageViewControllerDelegate {
     }
 }
 
-class BottomEdgeInteractionLayout: FloatingPanelLayout {
+class TopPositionedPanelLayout: FloatingPanelLayout {
     let position: FloatingPanelPosition = .top
     let initialState: FloatingPanelState = .full
 
@@ -553,7 +557,7 @@ class RemovablePanelLayout: FloatingPanelLayout {
         ]
     }
 
-    func backdropAlphaFor(position: FloatingPanelState) -> CGFloat {
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
         return 0.3
     }
 }
@@ -569,7 +573,7 @@ class RemovablePanelLandscapeLayout: FloatingPanelLayout {
         ]
     }
 
-    func backdropAlphaFor(position: FloatingPanelState) -> CGFloat {
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
         return 0.3
     }
 }
@@ -584,7 +588,7 @@ class ModalPanelLayout: FloatingPanelLayout {
         ]
     }
 
-    func backdropAlphaFor(position: FloatingPanelState) -> CGFloat {
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
         return 0.3
     }
 }
@@ -700,6 +704,8 @@ 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!
@@ -741,6 +747,10 @@ 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)
         }
@@ -801,6 +811,14 @@ 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)
@@ -1188,9 +1206,10 @@ class ThreeTabBarPanelLayout: FloatingPanelLayout {
         ]
     }
 
-    func backdropAlphaFor(position: FloatingPanelState) -> 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)
@@ -1297,3 +1316,67 @@ final class MultiPanelController: FloatingPanelController, FloatingPanelControll
         }
     }
 }
+
+class ImageViewController: UIViewController {
+    class PanelLayout: FloatingPanelLayout {
+        weak var targetGuide: UILayoutGuide?
+        init(targetGuide: UILayoutGuide?) {
+            self.targetGuide = targetGuide
+        }
+        let position: FloatingPanelPosition = .bottom
+        let initialState: FloatingPanelState = .full
+        var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+            if #available(iOS 11.0, *), let targetGuide = targetGuide {
+                return [
+                    .full: FloatingPanelAdaptiveLayoutAnchor(absoluteOffset: 0,
+                                                             contentLayout: targetGuide,
+                                                             referenceGuide: .superview),
+                    .half: FloatingPanelAdaptiveLayoutAnchor(fractionalOffset: 0.5,
+                                                             contentLayout: targetGuide,
+                                                             referenceGuide: .superview)
+                ]
+            } else {
+                return [
+                    .full: FloatingPanelLayoutAnchor(absoluteInset: 500,
+                                                     edge: .bottom,
+                                                     referenceGuide: .superview)
+                ]
+            }
+        }
+    }
+
+    @IBOutlet weak var headerView: UIView!
+    @IBOutlet weak var footerView: UIView!
+    @IBOutlet weak var scrollView: UIScrollView!
+    @IBOutlet weak var stackView: UIStackView!
+
+    enum Mode {
+        case onlyImage
+        case withHeaderFooter
+    }
+
+    @available(iOS 11.0, *)
+    func layoutGuideFor(mode: Mode) -> UILayoutGuide {
+        switch mode {
+        case .onlyImage:
+            self.headerView.isHidden = true
+            self.footerView.isHidden = true
+            return scrollView.contentLayoutGuide
+        case .withHeaderFooter:
+            self.headerView.isHidden = false
+            self.footerView.isHidden = false
+            let guide = UILayoutGuide()
+            view.addLayoutGuide(guide)
+
+            NSLayoutConstraint.activate([
+                scrollView.heightAnchor.constraint(equalTo: scrollView.contentLayoutGuide.heightAnchor),
+
+                guide.topAnchor.constraint(equalTo: stackView.topAnchor),
+                guide.leftAnchor.constraint(equalTo: stackView.leftAnchor),
+                guide.bottomAnchor.constraint(equalTo: stackView.bottomAnchor),
+                guide.rightAnchor.constraint(equalTo: stackView.rightAnchor),
+            ])
+            return guide
+        }
+    }
+}

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

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

Examples/SamplesObjC/SamplesObjC/ViewController.m

@@ -61,10 +61,10 @@
     return @{
         FloatingPanelState.Half: [[FloatingPanelLayoutAnchor alloc] initWithFractionalInset:0.5
                                                                                        edge:FloatingPanelReferenceEdgeTop
-                                                                         referenceGuide:FloatingPanelLayoutReferenceGuideSafeArea],
+                                                                             referenceGuide:FloatingPanelLayoutReferenceGuideSafeArea],
         FloatingPanelState.Tip: [[FloatingPanelLayoutAnchor alloc] initWithAbsoluteInset:44.0
                                                                                     edge:FloatingPanelReferenceEdgeBottom
-                                                                         referenceGuide:FloatingPanelLayoutReferenceGuideSafeArea],
+                                                                          referenceGuide:FloatingPanelLayoutReferenceGuideSafeArea],
     };
 }
 

FloatingPanel.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
 
   s.name                = "FloatingPanel"
-  s.version             = "2.0.0-beta.1"
+  s.version             = "2.1.0"
   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.
@@ -14,7 +14,7 @@ The new interface displays the related contents and utilities in parallel as a u
   s.platform            = :ios, "10.0"
   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']
+  s.swift_versions      = ['5.1', '5.2', '5.3']
 
   s.framework           = "UIKit"
 

FloatingPanel.xcodeproj/project.pbxproj

@@ -9,7 +9,7 @@
 /* Begin PBXBuildFile section */
 		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 */; };
+		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 /* ControllerTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DB9CF2151169500CA77B8 /* ControllerTests.swift */; };
@@ -56,7 +56,7 @@
 		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>"; };
+		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>"; };
 		545DB9C12151169500CA77B8 /* FloatingPanel.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = FloatingPanel.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		545DB9C42151169500CA77B8 /* FloatingPanel.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = FloatingPanel.h; sourceTree = "<group>"; };
@@ -142,7 +142,7 @@
 				5469F4B324B30F3500537F8A /* LayoutReferences.swift */,
 				5469F4AF24B30E1500537F8A /* LayoutAnchoring.swift */,
 				5450EEE321646DF500135936 /* Behavior.swift */,
-				54352E9721A521CA00CBCA08 /* PassThroughView.swift */,
+				54352E9721A521CA00CBCA08 /* PassthroughView.swift */,
 				54CDC5D2215B6D5A007D205C /* SurfaceView.swift */,
 				54CDC5D4215B6D8D007D205C /* BackdropView.swift */,
 				545DBA2A2152383100CA77B8 /* GrabberView.swift */,
@@ -328,7 +328,7 @@
 				54CFBFC3215CD045006B5735 /* Layout.swift in Sources */,
 				5469F4B424B30F3500537F8A /* LayoutReferences.swift in Sources */,
 				54CDC5D5215B6D8D007D205C /* BackdropView.swift in Sources */,
-				54352E9821A521CA00CBCA08 /* PassThroughView.swift in Sources */,
+				54352E9821A521CA00CBCA08 /* PassthroughView.swift in Sources */,
 				54CFBFC5215CD09C006B5735 /* Core.swift in Sources */,
 				54ABD7AF216CCFF7002E6C13 /* Logger.swift in Sources */,
 				545DB9E021511AC100CA77B8 /* Controller.swift in Sources */,

FloatingPanel.xcworkspace/contents.xcworkspacedata

@@ -10,9 +10,6 @@
    <Group
       location = "group:Examples"
       name = "Examples">
-      <FileRef
-         location = "group:SamplesObjC/SamplesObjC.xcodeproj">
-      </FileRef>
       <FileRef
          location = "group:Maps/Maps.xcodeproj">
       </FileRef>
@@ -22,5 +19,8 @@
       <FileRef
          location = "group:Samples/Samples.xcodeproj">
       </FileRef>
+      <FileRef
+         location = "group:SamplesObjC/SamplesObjC.xcodeproj">
+      </FileRef>
    </Group>
 </Workspace>

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.

README.md

@@ -21,7 +21,7 @@ The new interface displays the related contents and utilities in parallel as a u
 - [Installation](#installation)
     - [CocoaPods](#cocoapods)
     - [Carthage](#carthage)
-    - [Swift Package Manager with Xcode](#swift-package-manager-with-xcode)
+    - [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)
@@ -30,7 +30,7 @@ The new interface displays the related contents and utilities in parallel as a u
     - [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)
+        - [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)
@@ -81,12 +81,16 @@ 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 5.0+. Compatible with iOS 10.0+.
+FloatingPanel is written in Swift 5.0+. Compatible with iOS 11.0+.
 
-:pencil2: You would like to use Swift 4.0. Please use FloatingPanel v1.
+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
 
@@ -109,7 +113,7 @@ For [Carthage](https://github.com/Carthage/Carthage), add the following to your
 github "scenee/FloatingPanel"
 ```
 
-### Swift Package Manager with Xcode
+### Swift Package Manager
 
 Follow [this doc](https://developer.apple.com/documentation/swift_packages/adding_package_dependencies_to_your_app).
 
@@ -159,7 +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.
 
-: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).
+:pencil2: FloatingPanelController has the custom presentation controller. If you would like to customize the presentation/dismissal, please see [Transitioning](https://github.com/SCENEE/FloatingPanel/blob/master/Sources/Transitioning.swift).
 
 ## View hierarchy
 
@@ -247,7 +251,7 @@ Otherwise, `FloatingPanelController` fixes the content by the height of the top
 
 ### Customize the layout with `FloatingPanelLayout` protocol
 
-#### Change the initial layout.
+#### Change the initial layout
 
 ```swift
 class ViewController: UIViewController, FloatingPanelControllerDelegate {
@@ -258,8 +262,8 @@ class ViewController: UIViewController, FloatingPanelControllerDelegate {
 }
 
 class MyFloatingPanelLayout: FloatingPanelLayout {
-    let position = .bottom
-    let initialState = .tip
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .tip
     var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
         return [
             .full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
@@ -272,7 +276,7 @@ class MyFloatingPanelLayout: FloatingPanelLayout {
 
 ### Update your panel layout
 
-There are 2 ways to update the panel layout. 
+There are 2 ways to update the panel layout.
 
 1. Manually set `FloatingPanelController.layout` to the new layout object directly.
 
@@ -281,7 +285,7 @@ fpc.layout = MyPanelLayout()
 fpc.invalidateLayout() // If needed
 ```
 
-2. Returns an appropriate layout object in `floatingPanel(_:layoutFor:)` delegate.
+2. Returns an appropriate layout object in one of 2 `floatingPanel(_:layoutFor:)` delegates.
 
 ```swift
 class ViewController: UIViewController, FloatingPanelControllerDelegate {
@@ -289,6 +293,11 @@ class ViewController: UIViewController, FloatingPanelControllerDelegate {
     func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
         return MyFloatingPanelLayout()
     }
+
+    // OR
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor size: CGSize) -> FloatingPanelLayout {
+        return MyFloatingPanelLayout()
+    } 
 }
 ```
 
@@ -303,8 +312,8 @@ class ViewController: UIViewController, FloatingPanelControllerDelegate {
 }
 
 class LandscapePanelLayout: FloatingPanelLayout {
-    let position = .bottom
-    let initialState = .tip
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .tip
     var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
         return [
             .full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
@@ -327,19 +336,19 @@ class LandscapePanelLayout: FloatingPanelLayout {
 
 ```swift
 class IntrinsicPanelLayout: FloatingPanelLayout {
-    let position = .bottom
-    let initialState = .full
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .full
     var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
         return [
-            .full: FloatingPanelIntrinsicLayoutAnchor(absoluteInset: 0, referenceGuide: .safeArea),
-            .half: FloatingPanelIntrinsicLayoutAnchor(fractionalInset: 0.5, referenceGuide: .safeArea),
+            .full: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 0, referenceGuide: .safeArea),
+            .half: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.5, referenceGuide: .safeArea),
         ]
     }
     ...
 }
 ```
 
-✏️ `FloatingPanelIntrinsicLayout` is deprecated on v1.
+:pencil2: `FloatingPanelIntrinsicLayout` is deprecated on v1.
 
 #### Specify an anchor for each state by an inset of the `FloatingPanelController.view` frame
 
@@ -359,7 +368,7 @@ class MyFullScreenLayout: FloatingPanelLayout {
 }
 ```
 
-✏️ `FloatingPanelFullScreenLayout` is deprecated on v1.
+:pencil2: `FloatingPanelFullScreenLayout` is deprecated on v1.
 
 ### Customize the behavior with `FloatingPanelBehavior` protocol
 
@@ -383,7 +392,7 @@ class CustomPanelBehavior: FloatingPanelBehavior {
 }
 ```
 
-✏️ `floatingPanel(_ vc:behaviorFor:)` is deprecated on v1.
+:pencil2: `floatingPanel(_ vc:behaviorFor:)` is deprecated on v1.
 
 #### Activate the rubber-band effect on panel edges
 
@@ -521,7 +530,7 @@ func floatingPanelDidChangePosition(_ vc: FloatingPanelController) {
 
 #### Interrupt the delegate methods of `FloatingPanelController.panGestureRecognizer`
 
-`FloatingPanelPanGestureRecognizer.delegateProxy` is able to override the delegate methods by your own delegate object.
+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 {
@@ -579,6 +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

Sources/BackdropView.swift

@@ -1,9 +1,11 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
-/// A view that presents a backdrop interface behind a floating panel.
+/// 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

@@ -1,7 +1,8 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// 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.
@@ -24,7 +25,7 @@ public protocol FloatingPanelBehavior {
     @objc optional
     var momentumProjectionRate: CGFloat { get }
 
-    /// Asks the behavior if the floating panel should project a momentum of a user interaction to move the proposed position.
+    /// 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`.
@@ -33,48 +34,40 @@ public protocol FloatingPanelBehavior {
 
     /// 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.
+    /// 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 the behavior to activate the rubber band effect to a given edge of the surface view. By default, the effect is disabled.
+    /// 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
 }
 
-class FloatingPanelDefaultBehavior: FloatingPanelBehavior {
-    var springDecelerationRate: CGFloat {
+/// 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.
+open class FloatingPanelDefaultBehavior: FloatingPanelBehavior {
+    public init() {}
+
+    open var springDecelerationRate: CGFloat {
         return UIScrollView.DecelerationRate.fast.rawValue + 0.001
     }
 
-    var springResponseTime: CGFloat {
+    open var springResponseTime: CGFloat {
         return 0.4
     }
 
-    var momentumProjectionRate: CGFloat {
+    open var momentumProjectionRate: CGFloat {
         return UIScrollView.DecelerationRate.normal.rawValue
     }
 
-    func redirectionalProgress(_ fpc: FloatingPanelController, from: FloatingPanelState, to: FloatingPanelState) -> CGFloat {
+    open 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))
-    }
-
-    func allowsRubberBanding(for edge: UIRectEdge) -> Bool {
+    open func allowsRubberBanding(for edge: UIRectEdge) -> Bool {
         return false
     }
 }

Sources/Controller.swift

@@ -1,30 +1,33 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
+/// 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 `FloatingPanelDefaultLayout` object.
+    /// 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
 
-    // Returns a FloatingPanelLayout object. If you use the default one, you can use a `FloatingPanelDefaultLayout` object.
+    /// 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
 
-    /// Returns a UIViewPropertyAnimator object to add/present a floating panel to a position.
+    /// Returns a UIViewPropertyAnimator object to add/present the  panel to a position.
     ///
-    /// Default is the spring animator with 0.25 sec duration and `UIScrollView.DecelerationRate.fast` deceleration rate.
+    /// 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 floating panel from a position.
+    /// Returns a UIViewPropertyAnimator object to remove/dismiss a panel from a position.
     ///
-    /// Default is the spring animator with 0.25 sec duration and `UIScrollView.DecelerationRate.fast` deceleration rate.
+    /// Default is the spring animator with 0.25 secs.
     @objc(floatingPanel:animatorForDismissingWithVelocity:) optional
     func floatingPanel(_ fpc: FloatingPanelController, animatorForDismissingWith velocity: CGVector) -> UIViewPropertyAnimator
 
-    /// 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.
+    /// 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)
 
@@ -32,45 +35,50 @@ import UIKit
     @objc optional
     func floatingPanelShouldBeginDragging(_ fpc: FloatingPanelController) -> Bool
 
+    /// 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)
+    /// Called on start of dragging (may require some time and or distance to move)
     @objc optional
     func floatingPanelWillBeginDragging(_ fpc: FloatingPanelController)
 
-    // called on finger up if the user dragged. velocity is in points/second.
+    /// 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>)
 
-    // called on finger up if the user dragged. decelerate is true if it will continue moving afterwards
+    /// Called on finger up if the user dragged.
+    ///
+    /// If `attract` is true, it will continue moving afterwards to a nearby state anchor.
     @objc optional
-    func floatingPanelDidEndDragging(_ fpc: FloatingPanelController, willDecelerate decelerate: Bool)
+    func floatingPanelDidEndDragging(_ fpc: FloatingPanelController, willAttract attract: Bool)
 
+    /// 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 the panel should be removed when dragging ended at the specified location
+    /// Asks the delegate whether a panel should be removed when dragging ended at the specified location
     ///
-    /// This delegate method is called only when `FloatingPanelController.isRemovalInteractionEnabled` is set to true.
+    /// 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.
+    /// Called on start to remove its view controller from the parent view controller.
     @objc(floatingPanelWillRemove:)
     optional
     func floatingPanelWillRemove(_ fpc: FloatingPanelController)
 
-    // called when its view controller are removed from the parent view controller.
+    /// 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 tracked scroll view to be pinned when a floating panel moves
+    /// 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
@@ -83,7 +91,7 @@ import UIKit
 }
 
 ///
-/// 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 {
@@ -103,7 +111,7 @@ 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{
@@ -135,12 +143,13 @@ open class FloatingPanelController: UIViewController {
         return floatingPanel.panGestureRecognizer
     }
 
-    /// The current position of the floating panel controller's contents.
+    /// 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
@@ -189,7 +198,7 @@ open class FloatingPanelController: UIViewController {
         @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) }
@@ -202,6 +211,7 @@ open class FloatingPanelController: UIViewController {
         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 {
@@ -227,7 +237,7 @@ open class FloatingPanelController: UIViewController {
         setUp()
     }
 
-    /// Initialize a newly created floating panel controller.
+    /// Initialize a newly created panel controller.
     @objc
     public init(delegate: FloatingPanelControllerDelegate? = nil) {
         super.init(nibName: nil, bundle: nil)
@@ -264,7 +274,7 @@ open class FloatingPanelController: UIViewController {
     open override func loadView() {
         assert(self.storyboard == nil, "Storyboard isn't supported")
 
-        let view = PassThroughView()
+        let view = PassthroughView()
         view.backgroundColor = .clear
 
         backdropView.frame = view.bounds
@@ -279,7 +289,7 @@ open class FloatingPanelController: UIViewController {
     open override func viewDidLayoutSubviews() {
         super.viewDidLayoutSubviews()
         if #available(iOS 11.0, *) {
-            // Ensure the panel's static constraint after rotating a device in static mode
+            // Ensure to update the static constraint of a panel after rotating a device in static mode
             if contentMode == .static {
                 floatingPanel.layoutAdapter.updateStaticConstraint()
             }
@@ -289,7 +299,6 @@ open class FloatingPanelController: UIViewController {
                 self.update(safeAreaInsets: fp_safeAreaInsets)
             }
         }
-        floatingPanel.layoutAdapter.checkLayout()
     }
 
     open override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
@@ -431,7 +440,7 @@ 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 }
                 self.update(safeAreaInsets: self.view.safeAreaInsets)
@@ -468,8 +477,8 @@ open class FloatingPanelController: UIViewController {
         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 floating panel doens't work well")
-        assert((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 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 viewIndex < 0 {
             parent.view.addSubview(self.view)
@@ -532,7 +541,7 @@ open class FloatingPanelController: UIViewController {
         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 {
             vc.willMove(toParent: nil)
@@ -580,7 +589,7 @@ open class FloatingPanelController: UIViewController {
         }
     }
 
-    /// Cancel tracking the specifiy scroll view.
+    /// Cancel tracking the specify scroll view.
     ///
     @objc(untrackScrollView:)
     public func untrack(scrollView: UIScrollView) {
@@ -589,6 +598,14 @@ open class FloatingPanelController: UIViewController {
         }
     }
 
+    // MARK: - Accessibility
+
+    open override func accessibilityPerformEscape() -> Bool {
+        guard isRemovalInteractionEnabled else { return false }
+        dismiss(animated: true, completion: nil)
+        return true
+    }
+
     // MARK: - Utilities
 
     /// Updates the layout object from the delegate and lays out the views managed
@@ -596,19 +613,28 @@ 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.
     @objc
     public func invalidateLayout() {
         activateLayout(forceLayout: true)
     }
 
-    /// Returns the y-coordinate of the point at the origin of the surface view.
+    /// 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 }
@@ -623,6 +649,27 @@ extension FloatingPanelController {
         #endif
         delegate?.floatingPanelDidMove?(self)
     }
+
+    func animatorForPresenting(to: FloatingPanelState) -> UIViewPropertyAnimator {
+        if let animator = delegate?.floatingPanel?(self, animatorForPresentingTo: to) {
+            return animator
+        }
+        let timingParameters = UISpringTimingParameters(decelerationRate: UIScrollView.DecelerationRate.fast.rawValue,
+                                                       frequencyResponse: 0.25)
+        return UIViewPropertyAnimator(duration: 0.0,
+                                      timingParameters: timingParameters)
+    }
+
+    func animatorForDismissing(with velocity: CGVector) -> UIViewPropertyAnimator {
+        if let animator = delegate?.floatingPanel?(self, animatorForDismissingWith: velocity) {
+            return animator
+        }
+        let timingParameters = UISpringTimingParameters(decelerationRate: UIScrollView.DecelerationRate.fast.rawValue,
+                                                       frequencyResponse: 0.25,
+                                                       initialVelocity: velocity)
+        return UIViewPropertyAnimator(duration: 0.0,
+                                      timingParameters: timingParameters)
+    }
 }
 
 extension FloatingPanelController {

Sources/Core.swift

@@ -1,13 +1,12 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
 ///
-/// FloatingPanel presentation model
+/// The presentation model of FloatingPanel
 ///
 class Core: NSObject, UIGestureRecognizerDelegate {
-    // MUST be a weak reference to prevent UI freeze on the presentation modally
-    weak var viewcontroller: FloatingPanelController?
+    private weak var ownerVC: FloatingPanelController?
 
     let surfaceView: SurfaceView
     let backdropView: BackdropView
@@ -24,7 +23,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     private(set) var state: FloatingPanelState = .hidden {
         didSet {
             log.debug("state changed: \(oldValue) -> \(state)")
-            if let vc = viewcontroller {
+            if let vc = ownerVC {
                 vc.delegate?.floatingPanelDidChangePosition?(vc)
             }
         }
@@ -51,7 +50,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     // Scroll handling
     private var initialScrollOffset: CGPoint = .zero
     private var stopScrollDeceleration: Bool = false
-    private var scrollBouncable = false
+    private var scrollBounce = false
     private var scrollIndictorVisible = false
     private var grabberAreaFrame: CGRect {
         return surfaceView.grabberAreaFrame
@@ -60,7 +59,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     // MARK: - Interface
 
     init(_ vc: FloatingPanelController, layout: FloatingPanelLayout, behavior: FloatingPanelBehavior) {
-        viewcontroller = vc
+        ownerVC = vc
 
         surfaceView = SurfaceView()
         surfaceView.backgroundColor = .white
@@ -69,11 +68,8 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         backdropView.backgroundColor = .black
         backdropView.alpha = 0.0
 
-        self.layoutAdapter = LayoutAdapter(vc: vc,
-                                                        surfaceView: surfaceView,
-                                                        backdropView: backdropView,
-                                                        layout: layout)
-        self.behaviorAdapter = BehaviorAdapter(vc: vc, behavior: behavior)
+        layoutAdapter = LayoutAdapter(vc: vc, layout: layout)
+        behaviorAdapter = BehaviorAdapter(vc: vc, behavior: behavior)
 
         panGestureRecognizer = FloatingPanelPanGestureRecognizer()
 
@@ -101,7 +97,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
     private func move(from: FloatingPanelState, to: FloatingPanelState, animated: Bool, completion: (() -> Void)? = nil) {
         assert(layoutAdapter.validStates.contains(to), "Can't move to '\(to)' state because it's not valid in the layout")
-        guard let vc = viewcontroller else {
+        guard let vc = ownerVC else {
             completion?()
             return
         }
@@ -124,31 +120,39 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             let animator: UIViewPropertyAnimator
             switch (from, to) {
             case (.hidden, let to):
-                animator = vc.delegate?.floatingPanel?(vc, animatorForPresentingTo: to)
-                    ?? FloatingPanelDefaultBehavior().addPanelAnimator(vc, to: to)
+                animator = vc.animatorForPresenting(to: to)
             case (let from, .hidden):
                 let animationVector = CGVector(dx: abs(removalVector.dx), dy: abs(removalVector.dy))
-                animator = vc.delegate?.floatingPanel?(vc, animatorForDismissingWith: .zero)
-                    ?? FloatingPanelDefaultBehavior().removePanelAnimator(vc, from: from, with: animationVector)
+                animator = vc.animatorForDismissing(with: animationVector)
             default:
                 move(to: to, with: 0) {
+                    self.moveAnimator = nil
                     updateScrollView()
                     completion?()
                 }
                 return
             }
 
+            let shouldDoubleLayout = from == .hidden
+                && surfaceView.hasStackView()
+                && layoutAdapter.isIntrinsicAnchor(state: to)
+
             animator.addAnimations { [weak self] in
                 guard let `self` = self else { return }
 
                 self.state = to
                 self.updateLayout(to: to)
+
+                if shouldDoubleLayout {
+                    log.info("Lay out the surface again to modify an intrinsic size error according to UIStackView")
+                    self.updateLayout(to: to)
+                }
             }
             animator.addCompletion { [weak self] _ in
                 guard let `self` = self else { return }
                 self.animator = nil
                 updateScrollView()
-                self.viewcontroller?.notifyDidMove()
+                self.ownerVC?.notifyDidMove()
                 completion?()
             }
             self.animator = animator
@@ -162,7 +166,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                 self.lockScrollView()
 
             }
-            viewcontroller?.notifyDidMove()
+            ownerVC?.notifyDidMove()
             completion?()
         }
     }
@@ -177,7 +181,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         /* log.debug("currentY: \(currentY) translation: \(translation)") */
         let forwardY = (translation >= 0)
 
-        let segment = layoutAdapter.segument(at: cur, forward: forwardY)
+        let segment = layoutAdapter.segment(at: cur, forward: forwardY)
 
         let lowerState = segment.lower ?? layoutAdapter.edgeMostState
         let upperState = segment.upper ?? layoutAdapter.edgeLeastState
@@ -212,7 +216,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
         switch otherGestureRecognizer {
         case is FloatingPanelPanGestureRecognizer:
-            // All visiable panels' pan gesture should be recognized simultaneously.
+            // All visible panels' pan gesture should be recognized simultaneously.
             return true
         case is UIPanGestureRecognizer,
              is UISwipeGestureRecognizer,
@@ -228,7 +232,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         default:
             // Should recognize tap/long press gestures in parallel when the surface view is at an anchor position.
             let adapterY = layoutAdapter.position(for: state)
-            return abs(value(of: layoutAdapter.surfaceLocation) - adapterY) < (1.0 / surfaceView.traitCollection.displayScale)
+            return abs(value(of: layoutAdapter.surfaceLocation) - adapterY) < (1.0 / surfaceView.fp_displayScale)
         }
     }
 
@@ -238,7 +242,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         }
 
         if otherGestureRecognizer is FloatingPanelPanGestureRecognizer {
-            // If this panel is the farthest descendant of visiable panels,
+            // If this panel is the farthest descendant of visible panels,
             // its ancestors' pan gesture must wait for its pan gesture to fail
             if let view = otherGestureRecognizer.view, surfaceView.isDescendant(of: view) {
                 return true
@@ -290,7 +294,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
         switch otherGestureRecognizer {
         case is FloatingPanelPanGestureRecognizer:
-            // If this panel is the farthest descendant of visiable panels,
+            // If this panel is the farthest descendant of visible panels,
             // its pan gesture does not require its ancestors' pan gesture to fail
             if let view = otherGestureRecognizer.view, surfaceView.isDescendant(of: view) {
                 return false
@@ -321,7 +325,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
     @objc func handleBackdrop(tapGesture: UITapGestureRecognizer) {
         removalVector = .zero
-        viewcontroller?.remove()
+        ownerVC?.remove()
     }
 
     @objc func handle(panGesture: UIPanGestureRecognizer) {
@@ -332,7 +336,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             let velocity = value(of: panGesture.velocity(in: panGesture.view))
             let location = panGesture.location(in: surfaceView)
 
-            let belowEdgeMost = 0 > layoutAdapter.offsetFromEdgeMost + (1.0 / surfaceView.traitCollection.displayScale)
+            let belowEdgeMost = 0 > layoutAdapter.offsetFromEdgeMost + (1.0 / surfaceView.fp_displayScale)
 
             log.debug("""
                 scroll gesture(\(state):\(panGesture.state)) -- \
@@ -438,7 +442,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                 """)
 
             if interactionInProgress == false, isAttracting == false,
-                let vc = viewcontroller, vc.delegate?.floatingPanelShouldBeginDragging?(vc) == false {
+                let vc = ownerVC, vc.delegate?.floatingPanelShouldBeginDragging?(vc) == false {
                 return
             }
 
@@ -599,7 +603,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
         guard (pre != cur) else { return }
 
-        if let vc = viewcontroller {
+        if let vc = ownerVC {
             vc.delegate?.floatingPanelDidMove?(vc)
         }
     }
@@ -640,7 +644,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             return
         }
 
-        stopScrollDeceleration = (0 > layoutAdapter.offsetFromEdgeMost + (1.0 / surfaceView.traitCollection.displayScale)) // Projecting the dragging to the scroll dragging or not
+        stopScrollDeceleration = (0 > layoutAdapter.offsetFromEdgeMost + (1.0 / surfaceView.fp_displayScale)) // Projecting the dragging to the scroll dragging or not
         if stopScrollDeceleration {
             DispatchQueue.main.async { [weak self] in
                 guard let `self` = self else { return }
@@ -662,19 +666,19 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             case .left, .right:
                 removalVector = (distToHidden != 0) ? CGVector(dx: velocity.x/distToHidden, dy: 0.0) : .zero
             }
-            if shoulRemove(with: removalVector) {
-                viewcontroller?.remove()
+            if shouldRemove(with: removalVector) {
+                ownerVC?.remove()
                 return
             }
         }
 
-        if let vc = viewcontroller {
+        if let vc = ownerVC {
             vc.delegate?.floatingPanelWillEndDragging?(vc, withVelocity: velocity, targetState: &targetPosition)
         }
 
-        guard shouldDecelerate(to: targetPosition) else {
-            if let vc = viewcontroller {
-                vc.delegate?.floatingPanelDidEndDragging?(vc, willDecelerate: false)
+        guard shouldAttract(to: targetPosition) else {
+            if let vc = ownerVC {
+                vc.delegate?.floatingPanelDidEndDragging?(vc, willAttract: false)
             }
 
             self.state = targetPosition
@@ -683,8 +687,8 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             return
         }
 
-        if let vc = viewcontroller {
-            vc.delegate?.floatingPanelDidEndDragging?(vc, willDecelerate: true)
+        if let vc = ownerVC {
+            vc.delegate?.floatingPanelDidEndDragging?(vc, willAttract: true)
         }
 
         // Workaround: Disable a tracking scroll to prevent bouncing a scroll content in a panel animating
@@ -693,7 +697,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             scrollView.isScrollEnabled = false
         }
 
-        startAttration(to: targetPosition, with: velocity)
+        startAttraction(to: targetPosition, with: velocity)
 
         // Workaround: Reset `self.scrollView.isScrollEnabled`
         if let scrollView = scrollView, targetPosition != .full,
@@ -704,20 +708,21 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
     // MARK: - Behavior
 
-    private func shoulRemove(with velocityVector: CGVector) -> Bool {
-        guard let vc = viewcontroller else { return false }
+    private func shouldRemove(with velocityVector: CGVector) -> Bool {
+        guard let vc = ownerVC else { return false }
         if let result = vc.delegate?.floatingPanel?(vc, shouldRemoveAt: vc.surfaceLocation, with: velocityVector) {
             return result
         }
+        let threshold = CGFloat(5.5)
         switch layoutAdapter.position {
         case .top:
-            return (velocityVector.dy <= -10.0)
+            return (velocityVector.dy <= -threshold)
         case .left:
-            return (velocityVector.dx <= -10.0)
+            return (velocityVector.dx <= -threshold)
         case .bottom:
-            return (velocityVector.dy >= 10.0)
+            return (velocityVector.dy >= threshold)
         case .right:
-            return (velocityVector.dx >= 10.0)
+            return (velocityVector.dx >= threshold)
         }
     }
 
@@ -753,7 +758,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
         initialTranslation = translation
 
-        if let vc = viewcontroller {
+        if let vc = ownerVC {
             vc.delegate?.floatingPanelWillBeginDragging?(vc)
         }
 
@@ -787,16 +792,16 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         panGestureRecognizer.isEnabled = true
     }
 
-    private func shouldDecelerate(to targetState: FloatingPanelState) -> Bool {
+    private func shouldAttract(to targetState: FloatingPanelState) -> Bool {
         if layoutAdapter.position(for: targetState) == value(of: layoutAdapter.surfaceLocation) {
             return false
         }
         return true
     }
 
-    private func startAttration(to targetPosition: FloatingPanelState, with velocity: CGPoint) {
+    private func startAttraction(to targetPosition: FloatingPanelState, with velocity: CGPoint) {
         log.debug("startAnimation to \(targetPosition) -- velocity = \(value(of: velocity))")
-        guard let vc = viewcontroller else { return }
+        guard let vc = ownerVC else { return }
 
         isAttracting = true
         vc.delegate?.floatingPanelWillBeginAttracting?(vc, to: targetPosition)
@@ -811,7 +816,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         moveAnimator = NumericSpringAnimator(
             initialData: initialData,
             target: target,
-            displayScale: surfaceView.traitCollection.displayScale,
+            displayScale: surfaceView.fp_displayScale,
             decelerationRate: behaviorAdapter.springDecelerationRate,
             responseTime: behaviorAdapter.springResponseTime,
             update: { [weak self] data in
@@ -820,7 +825,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                 let current = self.value(of: self.layoutAdapter.surfaceLocation)
                 let translation = data.value - initialData.value
                 self.backdropView.alpha = self.getBackdropAlpha(at: current, with: translation)
-                self.viewcontroller?.notifyDidMove()
+                self.ownerVC?.notifyDidMove()
         },
             completion: { [weak self] in
                 guard let self = self else { return }
@@ -835,7 +840,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         self.isAttracting = false
         self.moveAnimator = nil
 
-        if let vc = viewcontroller {
+        if let vc = ownerVC {
             vc.delegate?.floatingPanelDidEndAttracting?(vc)
         }
 
@@ -892,7 +897,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         let distance = (currentY - layoutAdapter.position(for: state))
         let forwardY = velocity == 0 ? distance > 0 : velocity > 0
 
-        let segment = layoutAdapter.segument(at: pY, forward: forwardY)
+        let segment = layoutAdapter.segment(at: pY, forward: forwardY)
 
         var fromPos: FloatingPanelState
         var toPos: FloatingPanelState
@@ -902,7 +907,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
         if behaviorAdapter.shouldProjectMomentum(to: toPos) == false {
             log.debug("targetPosition -- negate projection: distance = \(distance)")
-            let segment = layoutAdapter.segument(at: currentY, forward: forwardY)
+            let segment = layoutAdapter.segment(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 {
@@ -939,7 +944,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         }
         log.debug("lock scroll view")
 
-        scrollBouncable = scrollView.bounces
+        scrollBounce = scrollView.bounces
         scrollIndictorVisible = scrollView.showsVerticalScrollIndicator
 
         scrollView.isDirectionalLockEnabled = true
@@ -952,7 +957,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         log.debug("unlock scroll view")
 
         scrollView.isDirectionalLockEnabled = false
-        scrollView.bounces = scrollBouncable
+        scrollView.bounces = scrollBounce
         scrollView.showsVerticalScrollIndicator = scrollIndictorVisible
     }
 
@@ -965,7 +970,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 
     private func contentOffsetForPinning(of scrollView: UIScrollView) -> CGPoint {
-        if let vc = viewcontroller, let origin = vc.delegate?.floatingPanel?(vc, contentOffsetForPinning: scrollView) {
+        if let vc = ownerVC, let origin = vc.delegate?.floatingPanel?(vc, contentOffsetForPinning: scrollView) {
             return origin
         }
         switch layoutAdapter.position {
@@ -1005,6 +1010,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 }
 
+/// A gesture recognizer that looks for panning (dragging) gestures in a panel.
 public final class FloatingPanelPanGestureRecognizer: UIPanGestureRecognizer {
     fileprivate weak var floatingPanel: Core?
     fileprivate var initialLocation: CGPoint = .zero
@@ -1016,6 +1022,10 @@ public final class FloatingPanelPanGestureRecognizer: UIPanGestureRecognizer {
             self.state = .began
         }
     }
+    /// The delegate of the gesture recognizer.
+    ///
+    /// - Note: The delegate is used by FloatingPanel itself. If you set your own delegate object, an
+    /// exception is raised. If you want to handle the methods of UIGestureRecognizerDelegate, you can use `delegateProxy`.
     public override weak var delegate: UIGestureRecognizerDelegate? {
         get {
             return super.delegate
@@ -1031,6 +1041,10 @@ public final class FloatingPanelPanGestureRecognizer: UIPanGestureRecognizer {
             super.delegate = newValue
         }
     }
+
+    /// An object to intercept the delegate of the gesture recognizer.
+    ///
+    /// If an object adopting `UIGestureRecognizerDelegate` is set, the delegate methods are proxied to it.
     public weak var delegateProxy: UIGestureRecognizerDelegate? {
         didSet {
             self.delegate = floatingPanel // Update the cached IMP
@@ -1040,7 +1054,7 @@ public final class FloatingPanelPanGestureRecognizer: UIPanGestureRecognizer {
 
 // MARK: - Animator
 
-class NumericSpringAnimator: NSObject {
+private class NumericSpringAnimator: NSObject {
     struct Data {
         let value: CGFloat
         let velocity: CGFloat

Sources/GrabberView.swift

@@ -1,7 +1,8 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
+/// A view that presents a grabber handle in the surface of a panel.
 @objc(FloatingPanelGrabberView)
 public class GrabberView: UIView {
 

Sources/Info.plist

@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>2.0.0-beta.1</string>
+	<string>2.1.0</string>
 	<key>CFBundleVersion</key>
 	<string>$(CURRENT_PROJECT_VERSION)</string>
 </dict>

Sources/Layout.swift

@@ -1,29 +1,26 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// 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 {
-    /// The position of the panel in the view of `FloatingPanelController`.
+    /// Returns the position of a panel in a `FloatingPanelController` view .
     @objc var position: FloatingPanelPosition { get }
 
-    /// The initial state when the layout is applied.
+    /// Returns the initial state when a panel is presented.
     @objc var initialState: FloatingPanelState { get }
 
-    /// The layout anchors to specify the snapping locations for each state.
+    /// Returns the layout anchors to specify the snapping locations for each state.
     @objc var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] { get }
 
-    /// 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.
+    /// Returns layout constraints to determine the cross dimension of a panel.
     @objc optional func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint]
 
-    /// Returns a CGFloat value to determine the backdrop view's alpha for a state.
-    ///
-    /// Default is 0.3 at full state, otherwise 0.0.
+    /// 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() {
@@ -64,8 +61,6 @@ struct LayoutSegment {
 
 class LayoutAdapter {
     weak var vc: FloatingPanelController!
-    private weak var surfaceView: SurfaceView!
-    private weak var backdropView: BackdropView!
     private let defaultLayout = FloatingPanelBottomLayout()
 
     fileprivate var layout: FloatingPanelLayout {
@@ -74,6 +69,12 @@ class LayoutAdapter {
         }
     }
 
+    private var surfaceView: SurfaceView {
+        return vc.surfaceView
+    }
+    private var backdropView: BackdropView {
+        return vc.backdropView
+    }
     private var safeAreaInsets: UIEdgeInsets {
         return vc?.fp_safeAreaInsets ?? .zero
     }
@@ -223,8 +224,7 @@ class LayoutAdapter {
                     }
                 }
             } else {
-                let displayScale = surfaceView.traitCollection.displayScale
-                pos = displayTrunc(edgePosition(surfaceView.frame), by: displayScale)
+                pos = displayTrunc(edgePosition(surfaceView.frame), by: surfaceView.fp_displayScale)
             }
             switch position {
             case .top, .bottom:
@@ -288,18 +288,13 @@ class LayoutAdapter {
         }
     }
 
-    init(vc: FloatingPanelController,
-         surfaceView: SurfaceView,
-         backdropView: BackdropView,
-         layout: FloatingPanelLayout) {
+    init(vc: FloatingPanelController, 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.traitCollection.displayScale)
+        let pos = displayTrunc(position(for: state), by: surfaceView.fp_displayScale)
         switch layout.position {
         case .top, .bottom:
             return CGPoint(x: 0.0, y: pos)
@@ -313,19 +308,39 @@ class LayoutAdapter {
         let anchor = layout.anchors[state] ?? self.hiddenAnchor
 
         switch anchor {
-        case let ianchor as FloatingPanelIntrinsicLayoutAnchor:
-            let surfaceIntrinsicLength = position.mainDimension(surfaceView.intrinsicContentSize)
-            let diff = ianchor.isAbsolute ? ianchor.offset : surfaceIntrinsicLength * ianchor.offset
+        case let anchor as FloatingPanelIntrinsicLayoutAnchor:
+            let intrinsicLength = position.mainDimension(surfaceView.intrinsicContentSize)
+            let diff = anchor.isAbsolute ? anchor.offset : intrinsicLength * anchor.offset
 
-            var referenceBoundsLength = position.mainDimension(bounds.size)
             switch position {
             case .top, .left:
-                return referenceBoundsLength - surfaceIntrinsicLength - diff
+                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 FloatingPanelAdaptiveLayoutAnchor:
+            let dimension = layout.position.mainDimension(anchor.contentLayoutGuide.layoutFrame.size)
+            let diff = anchor.distance(from: dimension)
+            var referenceBoundsLength = layout.position.mainDimension(bounds.size)
+            switch layout.position {
+            case .top, .left:
+                if anchor.referenceGuide == .safeArea {
+                    referenceBoundsLength += position.inset(safeAreaInsets)
+                }
+                return dimension - diff
             case .bottom, .right:
                 if anchor.referenceGuide == .safeArea {
                     referenceBoundsLength -= position.inset(safeAreaInsets)
                 }
-                return referenceBoundsLength - surfaceIntrinsicLength + diff
+                return referenceBoundsLength - dimension + diff
             }
         case let anchor as FloatingPanelLayoutAnchor:
             let referenceBounds = anchor.referenceGuide == .safeArea ? bounds.inset(by: safeAreaInsets) : bounds
@@ -343,7 +358,11 @@ class LayoutAdapter {
         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 {
@@ -360,7 +379,8 @@ class LayoutAdapter {
 
     private func referenceEdge(of anchor: FloatingPanelLayoutAnchoring) -> FloatingPanelReferenceEdge {
         switch anchor {
-        case is FloatingPanelIntrinsicLayoutAnchor:
+        case is FloatingPanelIntrinsicLayoutAnchor,
+            is FloatingPanelAdaptiveLayoutAnchor:
             switch position {
             case .top: return .top
             case .left: return .left
@@ -428,6 +448,10 @@ class LayoutAdapter {
             fitToBoundsConstraint?.priority = .defaultHigh
         }
 
+        updateStateConstraints()
+    }
+
+    private func updateStateConstraints() {
         NSLayoutConstraint.deactivate(fullConstraints + halfConstraints + tipConstraints + offConstraints)
 
         if let fullAnchor = layout.anchors[.full] {
@@ -491,8 +515,8 @@ class LayoutAdapter {
         // unsatisfiable constraints
 
         if self.interactionConstraint == nil {
-            // Actiavate `interactiveTopConstraint` for `fitToBounds` mode.
-            // It goes throught this path when the pan gesture state jumps
+            // Activate `interactiveTopConstraint` for `fitToBounds` mode.
+            // It goes through this path when the pan gesture state jumps
             // from .begin to .end.
             startInteraction(at: state)
         }
@@ -632,19 +656,31 @@ class LayoutAdapter {
         }
 
         let anchor = layout.anchors[self.edgeMostState]!
-        if anchor is FloatingPanelIntrinsicLayoutAnchor {
-            var constant = layout.position.mainDimension(surfaceView.intrinsicContentSize)
+        let surfaceAnchor = position.mainDimensionAnchor(surfaceView)
+        switch anchor {
+        case let anchor as FloatingPanelIntrinsicLayoutAnchor:
+            var constant = position.mainDimension(surfaceView.intrinsicContentSize)
             if anchor.referenceGuide == .safeArea {
                 constant += position.inset(safeAreaInsets)
             }
-            staticConstraint = position.mainDimensionAnchor(surfaceView).constraint(equalToConstant: constant)
-        } else {
+            staticConstraint = surfaceAnchor.constraint(equalToConstant: constant)
+        case let anchor as FloatingPanelAdaptiveLayoutAnchor:
+            let constant: CGFloat
+            if anchor.referenceGuide == .safeArea {
+                constant = position.inset(safeAreaInsets)
+            } else {
+                constant = 0.0
+            }
+            let baseAnchor = position.mainDimensionAnchor(anchor.contentLayoutGuide)
+            staticConstraint = surfaceAnchor.constraint(equalTo: baseAnchor, constant: constant)
+        default:
             switch position {
             case .top, .left:
-                staticConstraint = position.mainDimensionAnchor(surfaceView).constraint(equalToConstant: position(for: self.directionalMostState))
+                staticConstraint = surfaceAnchor.constraint(equalToConstant: position(for: self.directionalMostState))
             case .bottom, .right:
-                staticConstraint = position.mainDimensionAnchor(vc.view).constraint(equalTo: position.mainDimensionAnchor(surfaceView),
-                                                                                    constant: position(for: self.directionalLeastState))
+                let rootViewAnchor = position.mainDimensionAnchor(vc.view)
+                staticConstraint = rootViewAnchor.constraint(equalTo: surfaceAnchor,
+                                                             constant: position(for: self.directionalLeastState))
             }
         }
 
@@ -671,16 +707,16 @@ class LayoutAdapter {
         var const = initialConst + diff
 
         let base = position.mainDimension(vc.view.bounds.size)
-        // Rubberbanding top buffer
+        // Rubber-banding top buffer
         if allowsRubberBanding(.top), const < minConst {
             let buffer = minConst - const
-            const = minConst - rubberbandEffect(for: buffer, base: base)
+            const = minConst - rubberBandEffect(for: buffer, base: base)
         }
 
-        // Rubberbanding bottom buffer
+        // Rubber-banding bottom buffer
         if allowsRubberBanding(.bottom), const > maxConst {
             let buffer = const - maxConst
-            const = maxConst + rubberbandEffect(for: buffer, base: base)
+            const = maxConst + rubberBandEffect(for: buffer, base: base)
         }
 
         if overflow == false {
@@ -694,7 +730,7 @@ class LayoutAdapter {
     // 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 {
+    private func rubberBandEffect(for buffer: CGFloat, base: CGFloat) -> CGFloat {
         return (1.0 - (1.0 / ((buffer * 0.55 / base) + 1.0))) * base
     }
 
@@ -728,7 +764,11 @@ class LayoutAdapter {
             state = layout.initialState
         }
 
-        NSLayoutConstraint.deactivate(fullConstraints + halfConstraints + tipConstraints + offConstraints)
+        // 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)
@@ -762,25 +802,27 @@ class LayoutAdapter {
         return layout.backdropAlpha?(for: state) ?? defaultLayout.backdropAlpha(for: state)
     }
 
-    func checkLayout() {
+    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))")
-        let statePosOrder = activeStates.sorted(by: { position(for: $0) < position(for: $1) })
-        assert(sortedDirectionalStates == statePosOrder,
+        /* 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 segument(at pos: CGFloat, forward: Bool) -> LayoutSegment {
+    func segment(at pos: CGFloat, forward: Bool) -> LayoutSegment {
         /// ----------------------->Y
         /// --> forward                <-- backward
         /// |-------|===o===|-------|  |-------|-------|===o===|
         /// |-------|-------x=======|  |-------|=======x-------|
         /// |-------|-------|===o===|  |-------|===o===|-------|
-        /// pos: o/x, seguement: =
+        /// pos: o/x, segment: =
 
         let sortedStates = sortedDirectionalStates
 
@@ -804,7 +846,12 @@ extension LayoutAdapter {
 
 extension FloatingPanelController {
     var _layout: FloatingPanelLayout {
-        get { floatingPanel.layoutAdapter.layout }
-        set { floatingPanel.layoutAdapter.layout = newValue}
+        get {
+            floatingPanel.layoutAdapter.layout
+        }
+        set {
+            floatingPanel.layoutAdapter.layout = newValue
+            floatingPanel.layoutAdapter.checkLayout()
+        }
     }
 }

Sources/LayoutAnchoring.swift

@@ -1,19 +1,32 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// 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]
 }
 
+/// An object that defines how to settles a panel with insets from an edge of a reference rectangle.
 @objc final public class FloatingPanelLayoutAnchor: NSObject, FloatingPanelLayoutAnchoring /*, NSCopying */ {
+
+    /// Returns a layout anchor with the specified inset by an absolute value, edge and reference guide for a panel.
+    ///
+    /// The inset is an amount to inset a panel from an edge of the reference guide.  The edge refers to a panel
+    /// positioning.
     @objc public init(absoluteInset: CGFloat, edge: FloatingPanelReferenceEdge, referenceGuide: FloatingPanelLayoutReferenceGuide) {
         self.inset = absoluteInset
         self.referenceGuide = referenceGuide
         self.referenceEdge = edge
         self.isAbsolute = true
     }
+
+    /// Returns a layout anchor with the specified inset by a fractional value, edge and reference guide for a panel.
+    ///
+    /// The inset is an amount to inset a panel from the edge of the specified reference 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
@@ -22,8 +35,9 @@ import UIKit
     }
     let inset: CGFloat
     let isAbsolute: Bool
+    /// The reference rectangle area for the inset.
     @objc public let referenceGuide: FloatingPanelLayoutReferenceGuide
-    @objc public let referenceEdge: FloatingPanelReferenceEdge
+    @objc let referenceEdge: FloatingPanelReferenceEdge
 }
 
 public extension FloatingPanelLayoutAnchor {
@@ -80,14 +94,23 @@ public extension FloatingPanelLayoutAnchor {
     }
 }
 
+/// An object that defines how to settles a panel with the intrinsic size for a content.
 @objc final public class FloatingPanelIntrinsicLayoutAnchor: NSObject, FloatingPanelLayoutAnchoring /*, NSCopying */ {
+
+    /// Returns a layout anchor with the specified offset by an absolute value and reference guide for a panel.
+    ///
+    /// The offset is an amount to offset a position of panel that displays the entire content from an edge of
+    /// the reference guide.  The edge refers to a panel positioning.
     @objc public init(absoluteOffset offset: CGFloat, referenceGuide: FloatingPanelLayoutReferenceGuide = .safeArea) {
         self.offset = offset
         self.referenceGuide = referenceGuide
         self.isAbsolute = true
     }
-    // offset = 0.0 -> All content visible
-    // offset = 1.0 -> All content invisible
+
+    /// Returns a layout anchor with the specified offset by a fractional value and reference guide for 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
@@ -95,6 +118,8 @@ public extension FloatingPanelLayoutAnchor {
     }
     let offset: CGFloat
     let isAbsolute: Bool
+
+    /// The reference rectangle area for the offset
     @objc public let referenceGuide: FloatingPanelLayoutReferenceGuide
 }
 
@@ -115,3 +140,62 @@ public extension FloatingPanelIntrinsicLayoutAnchor {
         }
     }
 }
+
+/// An object that defines how to settles a panel with a layout guide of a content view.
+@objc final public class FloatingPanelAdaptiveLayoutAnchor: NSObject, FloatingPanelLayoutAnchoring /*, NSCopying */ {
+
+    /// Returns a layout anchor with the specified offset by an absolute value, layout guide to display content and reference guide for a panel.
+    ///
+    /// The offset is an amount to offset a position of panel that displays the entire content of the specified guide from an edge of
+    /// the reference guide.  The edge refers to a panel positioning.
+    @objc public init(absoluteOffset offset: CGFloat, contentLayout: UILayoutGuide, referenceGuide: FloatingPanelLayoutReferenceGuide = .safeArea) {
+        self.offset = offset
+        self.contentLayoutGuide = contentLayout
+        self.referenceGuide = referenceGuide
+        self.isAbsolute = true
+
+    }
+
+    /// Returns a layout anchor with the specified offset by a fractional value, layout guide to display content and reference guide for 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, contentLayout: UILayoutGuide, referenceGuide: FloatingPanelLayoutReferenceGuide = .safeArea) {
+        self.offset = offset
+        self.contentLayoutGuide = contentLayout
+        self.referenceGuide = referenceGuide
+        self.isAbsolute = false
+    }
+    fileprivate let offset: CGFloat
+    fileprivate let isAbsolute: Bool
+    let contentLayoutGuide: UILayoutGuide
+    @objc public let referenceGuide: FloatingPanelLayoutReferenceGuide
+}
+
+public extension FloatingPanelAdaptiveLayoutAnchor {
+    func layoutConstraints(_ vc: FloatingPanelController, for position: FloatingPanelPosition) -> [NSLayoutConstraint] {
+        let layoutGuide = referenceGuide.layoutGuide(vc: vc)
+        let offsetAnchor: NSLayoutDimension
+        switch position {
+        case .top:
+            offsetAnchor = layoutGuide.topAnchor.anchorWithOffset(to: vc.surfaceView.bottomAnchor)
+        case .left:
+            offsetAnchor = layoutGuide.leftAnchor.anchorWithOffset(to: vc.surfaceView.rightAnchor)
+        case .bottom:
+            offsetAnchor = vc.surfaceView.topAnchor.anchorWithOffset(to: layoutGuide.bottomAnchor)
+        case .right:
+            offsetAnchor = vc.surfaceView.leftAnchor.anchorWithOffset(to: layoutGuide.rightAnchor)
+        }
+        if isAbsolute {
+            return [offsetAnchor.constraint(equalTo: position.mainDimensionAnchor(contentLayoutGuide), constant: -offset)]
+        } else {
+            return [offsetAnchor.constraint(equalTo: position.mainDimensionAnchor(contentLayoutGuide), multiplier: (1 - offset))]
+        }
+    }
+}
+
+extension FloatingPanelAdaptiveLayoutAnchor {
+    func distance(from dimension: CGFloat) -> CGFloat {
+        return isAbsolute ? offset : dimension * offset
+    }
+}

Sources/LayoutReferences.swift

@@ -1,7 +1,8 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// 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
@@ -26,6 +27,7 @@ extension FloatingPanelReferenceEdge {
     }
 }
 
+/// Constants that specify a layout guide to lay out a panel.
 @objc public enum FloatingPanelLayoutReferenceGuide: Int {
     case superview = 0
     case safeArea = 1

Sources/Logger.swift

@@ -1,4 +1,4 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import Foundation
 import os.log

Sources/PassthroughView.swift

@@ -1,9 +1,9 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
-@objc(FloatingPanelPassThroughView)
-class PassThroughView: 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

@@ -1,7 +1,8 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// 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

Sources/State.swift

@@ -1,7 +1,8 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// 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
@@ -18,7 +19,9 @@ public class FloatingPanelState: NSObject, NSCopying, RawRepresentable {
         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 {
@@ -33,9 +36,13 @@ public class FloatingPanelState: NSObject, NSCopying, RawRepresentable {
         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)
 }
 

Sources/SurfaceView.swift

@@ -1,38 +1,41 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// 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 the surface shadow is displayed.
+        /// A Boolean indicating whether a shadow is displayed.
         @objc
         public var hidden: Bool = false
 
-        /// The color of the surface shadow.
+        /// The color of a shadow.
         @objc
         public var color: UIColor = .black
 
-        /// The offset (in points) of the surface shadow.
+        /// The offset (in points) of a shadow.
         @objc
         public var offset: CGSize = CGSize(width: 0.0, height: 1.0)
 
-        /// The opacity of the surface shadow.
+        /// The opacity of a shadow.
         @objc
         public var opacity: Float = 0.2
 
-        /// The blur radius (in points) used to render the surface shadow.
+        /// The blur radius (in points) used to render a shadow.
         @objc
         public var radius: CGFloat = 3
 
-        // The inflated amount of the surface shadow prior to applying the blur.
+        /// The inflated amount of a shadow prior to applying the blur.
         @objc
         public var spread: CGFloat = 0
 
     }
-    /// The background color.
+    /// The background color of a surface view
     public var backgroundColor: UIColor? = {
         if #available(iOS 13, *) {
             return UIColor.systemBackground
@@ -41,29 +44,29 @@ public class SurfaceAppearance: NSObject {
         }
     }()
 
-    /// The radius to use when drawing top rounded corners.
+    /// 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 width of the surface border.
+    /// The border width of a surface view.
     public var borderColor: UIColor?
 
-    /// The color of the surface border.
+    /// The border color of a surface view.
     public var borderWidth: CGFloat = 0.0
 }
 
-/// A view that presents a surface interface in a floating panel.
+/// 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.
+    /// A `FloatingPanelGrabberView` 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.
+    /// 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.
@@ -71,18 +74,18 @@ public class SurfaceView: UIView {
         setNeedsUpdateConstraints()
     } }
 
-    /// The offset from the interactive edge which prevents the conetent scroll
+    /// The offset from the move edge to prevent the content scroll
     public var grabberAreaOffset: CGFloat = 36.0
 
     /// The grabber handle size
     ///
-    /// On left/right position, the width dimension is used as the height of `grabberHandle`, and vice versa.
+    /// 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()
     } }
 
-    /// A root view of a content view controller
-    public weak var contentView: UIView!
+    /// 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 {
@@ -97,6 +100,7 @@ public class SurfaceView: UIView {
         set { appearance.backgroundColor = newValue; setNeedsLayout() }
     }
 
+    /// The appearance settings for a surface view.
     public var appearance = SurfaceAppearance() { didSet {
         shadowLayers = appearance.shadows.map { _ in CAShapeLayer() }
         setNeedsLayout()
@@ -107,7 +111,7 @@ public class SurfaceView: UIView {
         setNeedsUpdateConstraints()
     } }
 
-    /// The view presents an actual surface shape.
+    /// 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
@@ -118,7 +122,7 @@ public class SurfaceView: 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 floating panel, for instance,
+            // when the contentMode is changed after laying out a panel, for instance,
             // after calling viewDidAppear(_:) of the parent view controller.
             setNeedsUpdateConstraints()
         }
@@ -415,7 +419,7 @@ public class SurfaceView: UIView {
             rightConstraint,
             bottomConstraint,
         ].map {
-            $0.priority = .defaultHigh;
+            $0.priority = .required - 1;
             $0.identifier = "FloatingPanel-surface-content"
             return $0;
         })
@@ -424,4 +428,8 @@ public class SurfaceView: UIView {
         self.contentViewRightConstraint = rightConstraint
         self.contentViewBottomConstraint = bottomConstraint
     }
+
+    func hasStackView() -> Bool {
+        return contentView?.subviews.reduce(false) { $0 || ($1 is UIStackView) } ?? false
+    }
 }

Sources/Transitioning.swift

@@ -1,4 +1,4 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
@@ -21,7 +21,7 @@ class ModalTransition: NSObject, UIViewControllerTransitioningDelegate {
 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()
     }
 
@@ -44,8 +44,15 @@ class PresentationController: UIPresentationController {
 
     override func containerViewWillLayoutSubviews() {
         guard
-            let fpc = presentedViewController as? FloatingPanelController
-            else { fatalError() }
+            let fpc = presentedViewController as? FloatingPanelController,
+            /**
+             This condition fixes https://github.com/SCENEE/FloatingPanel/issues/369.
+             The issue is that this method is called in presenting a
+             UIImagePickerViewController and then a FloatingPanelController
+             view is added unnecessarily.
+             */
+            fpc.presentedViewController == nil
+            else { return }
 
         /*
          * Layout the views managed by `FloatingPanelController` here for the
@@ -54,7 +61,7 @@ class PresentationController: UIPresentationController {
         addFloatingPanel()
 
         // Forward touch events to the presenting view controller
-        (fpc.view as? PassThroughView)?.eventForwardingView = presentingViewController.view
+        (fpc.view as? PassthroughView)?.eventForwardingView = presentingViewController.view
     }
 
     @objc func handleBackdrop(tapGesture: UITapGestureRecognizer) {
@@ -79,8 +86,7 @@ class ModalPresentTransition: NSObject, UIViewControllerAnimatedTransitioning {
             let fpc = transitionContext?.viewController(forKey: .to) as? FloatingPanelController
         else { fatalError()}
 
-        let animator = fpc.delegate?.floatingPanel?(fpc, animatorForPresentingTo: fpc.layout.initialState)
-            ?? FloatingPanelDefaultBehavior().addPanelAnimator(fpc, to: fpc.layout.initialState)
+        let animator = fpc.animatorForPresenting(to: fpc.layout.initialState)
         return TimeInterval(animator.duration)
     }
 
@@ -101,8 +107,7 @@ class ModalDismissTransition: NSObject, UIViewControllerAnimatedTransitioning {
             let fpc = transitionContext?.viewController(forKey: .from) as? FloatingPanelController
         else { fatalError()}
 
-        let animator = fpc.delegate?.floatingPanel?(fpc, animatorForDismissingWith: .zero)
-            ?? FloatingPanelDefaultBehavior().removePanelAnimator(fpc, from: fpc.state, with: .zero)
+        let animator = fpc.animatorForDismissing(with: .zero)
         return TimeInterval(animator.duration)
     }
 

Sources/UIExtensions.swift

@@ -1,4 +1,4 @@
-// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
 
 import UIKit
 
@@ -72,7 +72,7 @@ extension UIViewController {
 }
 
 // The reason why UIView has no extensions of safe area insets and top/bottom guides
-// is for iOS10 compat.
+// is for iOS10 compatibility.
 extension UIView {
     var fp_safeAreaLayoutGuide: LayoutGuideProvider {
         if #available(iOS 11.0, *) {
@@ -85,6 +85,19 @@ extension UIView {
     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 {
@@ -112,7 +125,7 @@ extension UIGestureRecognizer.State: CustomDebugStringConvertible {
         case .changed: return "changed"
         case .failed: return "failed"
         case .cancelled: return "cancelled"
-        case .ended: return "endeded"
+        case .ended: return "ended"
         case .possible: return "possible"
         @unknown default: return ""
         }

Tests/ControllerTests.swift

@@ -86,7 +86,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .full)
             XCTAssertEqual(delegate.position, .full)
-            wait(for: [exp], timeout: 0.5)
+            wait(for: [exp], timeout: 1.0)
         }
 
         XCTContext.runActivity(named: "move to half(animated)") { act in
@@ -97,7 +97,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .half)
             XCTAssertEqual(delegate.position, .half)
-            wait(for: [exp], timeout: 0.8)
+            wait(for: [exp], timeout: 1.0)
         }
 
         XCTContext.runActivity(named: "move to tip(animated)") { act in
@@ -108,7 +108,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .tip)
             XCTAssertEqual(delegate.position, .tip)
-            wait(for: [exp], timeout: 0.8)
+            wait(for: [exp], timeout: 1.0)
         }
 
         fpc.move(to: .hidden, animated: true)
@@ -159,7 +159,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .full)
             XCTAssertEqual(delegate.position, .full)
-            wait(for: [exp], timeout: 0.5)
+            wait(for: [exp], timeout: 1.0)
         }
 
         XCTContext.runActivity(named: "move to half(animated)") { act in
@@ -170,7 +170,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .half)
             XCTAssertEqual(delegate.position, .half)
-            wait(for: [exp], timeout: 0.8)
+            wait(for: [exp], timeout: 1.0)
         }
 
         XCTContext.runActivity(named: "move to tip(animated)") { act in
@@ -181,7 +181,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .tip)
             XCTAssertEqual(delegate.position, .tip)
-            wait(for: [exp], timeout: 0.8)
+            wait(for: [exp], timeout: 1.0)
         }
 
         fpc.move(to: .hidden, animated: true)
@@ -314,7 +314,7 @@ class ControllerTests: XCTestCase {
         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.traitCollection.displayScale)
+        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)

Tests/LayoutTests.swift

@@ -469,7 +469,11 @@ class LayoutTests: XCTestCase {
                 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))
-                XCTAssertEqual(c.secondAnchor, prop.result.secondAnchor, 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)
         }
     }
@@ -532,7 +536,11 @@ class LayoutTests: XCTestCase {
                 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))
-                XCTAssertEqual(c.secondAnchor, prop.result.secondAnchor, 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)
         }
     }
@@ -641,9 +649,9 @@ class LayoutTests: XCTestCase {
 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 segument = floatingPanel.layoutAdapter.segument(at: pos, forward: forwardY)
-        XCTAssertEqual(segument.lower, lowr, line: line)
-        XCTAssertEqual(segument.upper, upper, line: line)
+        let segment = floatingPanel.layoutAdapter.segment(at: pos, forward: forwardY)
+        XCTAssertEqual(segment.lower, lowr, line: line)
+        XCTAssertEqual(segment.upper, upper, line: line)
     }
 }
 

Tests/SurfaceViewTests.swift

@@ -59,7 +59,7 @@ class SurfaceViewTests: XCTestCase {
             surface.containerOverflow = height
             surface.setNeedsLayout()
             surface.layoutIfNeeded()
-            XCTAssertEqual(surface.contentView.frame, surface.bounds)
+            XCTAssertEqual(surface.contentView?.frame ?? .zero, surface.bounds)
         }
 
         XCTContext.runActivity(named: "Top sheet") { _ in
@@ -75,7 +75,7 @@ class SurfaceViewTests: XCTestCase {
             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, from: surface.containerView),
+            XCTAssertEqual(surface.convert(surface.contentView?.frame ?? .zero, from: surface.containerView),
                            surface.bounds)
         }
     }
@@ -146,22 +146,22 @@ class SurfaceViewTests: XCTestCase {
             let contentView = UIView()
             surface.set(contentView: contentView)
             surface.layoutIfNeeded()
-            XCTAssertEqual(surface.contentView.frame, surface.bounds)
+            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, surface.bounds.inset(by: surface.contentPadding))
+            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, surface.bounds)
+            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, surface.bounds.inset(by: surface.contentPadding))
+            XCTAssertEqual(surface.contentView?.frame ?? .zero, surface.bounds.inset(by: surface.contentPadding))
         }
     }
 
@@ -170,13 +170,13 @@ class SurfaceViewTests: XCTestCase {
         let contentView = UIView()
         surface.set(contentView: contentView)
         surface.layoutIfNeeded()
-        XCTAssertEqual(surface.contentView.frame, surface.bounds)
+        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, surface.containerView.bounds.inset(by: surface.contentPadding))
+        XCTAssertEqual(surface.contentView?.frame ?? .zero, surface.containerView.bounds.inset(by: surface.contentPadding))
     }
 
     func test_surfaceView_cornderRaduis() {