Version 2.4.1

Co-authored-by: CodingIran <codingiran@163.com>

.github/FUNDING.yml

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

.github/workflows/ci.yml

@@ -0,0 +1,104 @@
+name: ci
+
+on: 
+  push:
+    branches: 
+      - master
+  pull_request:
+    branches: 
+      - '*'
+
+jobs:
+  build:
+    runs-on: macOS-11
+    steps:
+    - uses: actions/checkout@v1
+    - name: "Swift 5.4"
+      run: xcodebuild -scheme FloatingPanel SWIFT_VERSION=5.4 clean build
+      env:
+        DEVELOPER_DIR: /Applications/Xcode_12.5.1.app/Contents/Developer
+    - name: "Swift 5.5"
+      run: xcodebuild -scheme FloatingPanel SWIFT_VERSION=5.5 clean build
+      env:
+        DEVELOPER_DIR: /Applications/Xcode_13.0.app/Contents/Developer
+
+  build_compat:
+    runs-on: macOS-10.15
+    steps:
+    - uses: actions/checkout@v1
+    - name: "Swift 5.1"
+      run: xcodebuild -scheme FloatingPanel SWIFT_VERSION=5.1 clean build
+      env:
+        DEVELOPER_DIR: /Applications/Xcode_11.3.1.app/Contents/Developer
+    - name: "Swift 5.2"
+      run: xcodebuild -scheme FloatingPanel SWIFT_VERSION=5.2 clean build
+      env:
+        DEVELOPER_DIR: /Applications/Xcode_11.7.app/Contents/Developer
+    - name: "Swift 5.3"
+      run: xcodebuild -scheme FloatingPanel SWIFT_VERSION=5.3 clean build
+      env:
+        DEVELOPER_DIR: /Applications/Xcode_12.4.app/Contents/Developer
+
+  testing:
+    runs-on: macOS-11
+    steps:
+    - uses: actions/checkout@v1
+    - name: "Testing in iOS 14.5"
+      run: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=14.5,name=iPhone 12 Pro'
+      env:
+        DEVELOPER_DIR: /Applications/Xcode_12.5.1.app/Contents/Developer
+    - name: "Testing in iOS 15.0"
+      run: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=15.0,name=iPhone 13 Pro'
+      env:
+        DEVELOPER_DIR: /Applications/Xcode_13.0.app/Contents/Developer
+
+  testing_compat:
+    runs-on: macOS-10.15
+    steps:
+    - uses: actions/checkout@v1
+    - name: "Testing in iOS 13.7"
+      run: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=13.7,name=iPhone 11 Pro'
+      env:
+        DEVELOPER_DIR: /Applications/Xcode_11.7.app/Contents/Developer
+    - name: "Testing in iOS 14.4"
+      run: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=14.4,name=iPhone 12 Pro'
+      env:
+        DEVELOPER_DIR: /Applications/Xcode_12.4.app/Contents/Developer
+
+  example:
+    runs-on: macOS-11
+    env:
+      DEVELOPER_DIR: /Applications/Xcode_13.0.app/Contents/Developer
+    steps:
+    - uses: actions/checkout@v1
+    - name: "Build Maps"
+      run: xcodebuild -workspace FloatingPanel.xcworkspace -scheme Maps -sdk iphonesimulator clean build
+    - name: "Build Stocks"
+      run: xcodebuild -workspace FloatingPanel.xcworkspace -scheme Stocks -sdk iphonesimulator clean build
+    - name: "Build Samples"
+      run: xcodebuild -workspace FloatingPanel.xcworkspace -scheme Samples -sdk iphonesimulator clean build
+
+  swiftpm:
+    runs-on: macOS-11
+    env:
+      DEVELOPER_DIR: /Applications/Xcode_13.0.app/Contents/Developer
+    steps:
+    - uses: actions/checkout@v1
+    - name: "Swift Package build"
+      run: swift build -Xswiftc "-sdk" -Xswiftc "`xcrun --sdk iphonesimulator --show-sdk-path`" -Xswiftc "-target" -Xswiftc "x86_64-apple-ios14.3-simulator"
+
+  carthage:
+    runs-on: macOS-11
+    steps:
+    - uses: actions/checkout@v1
+    - name: "Carthage build"
+      run: carthage build --use-xcframeworks --no-skip-current
+
+  cocoapods:
+    runs-on: macOS-11
+    steps:
+    - uses: actions/checkout@v1
+    - name: "CocoaPods: pod lib lint"
+      run: pod lib lint --allow-warnings
+    - name: "CocoaPods: pod spec lint"
+      run: pod spec lint --allow-warnings

.swiftformat

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

@@ -1,74 +0,0 @@
-language: objective-c
-branches:
-  only:
-    - master
-env:
-  global:
-  - LANG=en_US.UTF-8
-  - LC_ALL=en_US.UTF-8
-jobs:
-  include:
-  - stage: "Builds"
-    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: xcode11.3
-    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"
-    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: xcode11.6
-    name: "iPhone 7 (iOS 11.4)"
-  - 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: xcode11.6
-    script: xcodebuild -workspace FloatingPanel.xcworkspace -scheme Maps -sdk iphonesimulator clean build
-    name: "Maps"
-  - script: xcodebuild -workspace FloatingPanel.xcworkspace -scheme Stocks -sdk iphonesimulator clean build
-    osx_image: xcode11.6
-    name: "Stocks"
-  - script: xcodebuild -workspace FloatingPanel.xcworkspace -scheme Samples -sdk iphonesimulator clean build
-    osx_image: xcode11.6
-    name: "Samples"
-  - script: xcodebuild -workspace FloatingPanel.xcworkspace -scheme SamplesObjC -sdk iphonesimulator clean build
-    osx_image: xcode11.6
-    name: "SamplesObjC"
-
-  - stage: "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: xcode11.6
-    before_install: 
-    - gem install cocoapods
-    script:
-    - pod spec lint --allow-warnings
-    - pod lib lint --allow-warnings

Documentation/FloatingPanel 2.0 Migration Guide.md

@@ -194,8 +194,8 @@ class MyPanelIntrinsicLayout: FloatingPanelLayout {
     var initialState: FloatingPanelState { .full }
     var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
         return [
-            .full: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 16.0, referenceGuide: .safeArea)
-            .half: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.5, referenceGuide: .safeArea)
+            .full: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 16.0, referenceGuide: .safeArea),
+            .half: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.5, referenceGuide: .safeArea),
             .tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .bottom, referenceGuide: .safeArea)
         ]
     }

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>
@@ -28,6 +28,7 @@
                                 <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"/>
@@ -233,6 +233,7 @@
                                 <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

@@ -83,14 +83,17 @@ class ViewController: UIViewController {
     func layoutPanelForPhone() {
         fpc.track(scrollView: searchVC.tableView) // Only track the tabvle view on iPhone
         fpc.addPanel(toParent: self, animated: true)
-        fpc.setApearanceForPhone()
-        detailFpc.setApearanceForPhone()
+        fpc.setAppearanceForPhone()
+        detailFpc.setAppearanceForPhone()
     }
 }
 
 extension FloatingPanelController {
-    func setApearanceForPhone() {
+    func setAppearanceForPhone() {
         let appearance = SurfaceAppearance()
+        if #available(iOS 13.0, *) {
+            appearance.cornerCurve = .continuous
+        }
         appearance.cornerRadius = 8.0
         appearance.backgroundColor = .clear
         surfaceView.appearance = appearance
@@ -114,19 +117,27 @@ 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)
+    }
+
+    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/Samples.xcodeproj/project.pbxproj

@@ -7,17 +7,32 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		5442E22425FC51AF00A26F43 /* ImageViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5442E22325FC51AF00A26F43 /* ImageViewController.swift */; };
+		5442E22825FC51E200A26F43 /* MultiPanelController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5442E22725FC51E200A26F43 /* MultiPanelController.swift */; };
+		5442E22C25FC521F00A26F43 /* SettingsViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5442E22B25FC521F00A26F43 /* SettingsViewController.swift */; };
+		5442E23025FC525200A26F43 /* TabBarViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5442E22F25FC525200A26F43 /* TabBarViewController.swift */; };
+		5442E23425FC528400A26F43 /* DetailViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5442E23325FC528400A26F43 /* DetailViewController.swift */; };
+		5442E23A25FC52CD00A26F43 /* ModalViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5442E23925FC52CD00A26F43 /* ModalViewController.swift */; };
+		5442E24025FC533800A26F43 /* DebugTableViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5442E23F25FC533800A26F43 /* DebugTableViewController.swift */; };
+		5442E24425FC538200A26F43 /* InspectorViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5442E24325FC538200A26F43 /* InspectorViewController.swift */; };
+		5442E24A25FC53C100A26F43 /* DebugTextViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5442E24925FC53C100A26F43 /* DebugTextViewController.swift */; };
+		5442E25225FC541700A26F43 /* NestedScrollViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5442E25125FC541700A26F43 /* NestedScrollViewController.swift */; };
+		54496C59263A7E5A0031E0C8 /* UseCaseController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54496C58263A7E5A0031E0C8 /* UseCaseController.swift */; };
 		545DB9EE21511E6300CA77B8 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DB9ED21511E6300CA77B8 /* AppDelegate.swift */; };
-		545DB9F021511E6300CA77B8 /* ViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DB9EF21511E6300CA77B8 /* ViewController.swift */; };
+		545DB9F021511E6300CA77B8 /* MainViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DB9EF21511E6300CA77B8 /* MainViewController.swift */; };
 		545DB9F321511E6300CA77B8 /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 545DB9F121511E6300CA77B8 /* Main.storyboard */; };
 		545DB9F521511E6400CA77B8 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 545DB9F421511E6400CA77B8 /* Assets.xcassets */; };
 		545DB9F821511E6400CA77B8 /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 545DB9F621511E6400CA77B8 /* LaunchScreen.storyboard */; };
 		545DBA0321511E6400CA77B8 /* SampleTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DBA0221511E6400CA77B8 /* SampleTests.swift */; };
 		545DBA0E21511E6400CA77B8 /* SampleUITests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DBA0D21511E6400CA77B8 /* SampleUITests.swift */; };
+		546341A125C6415100CA0596 /* UseCase.swift in Sources */ = {isa = PBXBuildFile; fileRef = 546341A025C6415100CA0596 /* UseCase.swift */; };
+		546341AC25C6426500CA0596 /* CustomState.swift in Sources */ = {isa = PBXBuildFile; fileRef = 546341AB25C6426500CA0596 /* CustomState.swift */; };
 		549D23CB233C7779008EF4D7 /* FloatingPanel.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 549D23CA233C7779008EF4D7 /* FloatingPanel.framework */; };
 		549D23CC233C7779008EF4D7 /* FloatingPanel.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 549D23CA233C7779008EF4D7 /* FloatingPanel.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
-		54B51116216AFE5F0033A6F3 /* UIExtensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54B51115216AFE5F0033A6F3 /* UIExtensions.swift */; };
-		54CDC5D8215BBE23007D205C /* UIComponents.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CDC5D7215BBE23007D205C /* UIComponents.swift */; };
+		54B51116216AFE5F0033A6F3 /* Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54B51115216AFE5F0033A6F3 /* Extensions.swift */; };
+		54CDC5D8215BBE23007D205C /* Components.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CDC5D7215BBE23007D205C /* Components.swift */; };
+		54EAD35B263A75EB006A36EA /* Layouts.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54EAD35A263A75EB006A36EA /* Layouts.swift */; };
+		54EAD365263A765F006A36EA /* PagePanelController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54EAD364263A765F006A36EA /* PagePanelController.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -52,9 +67,20 @@
 /* End PBXCopyFilesBuildPhase section */
 
 /* Begin PBXFileReference section */
+		5442E22325FC51AF00A26F43 /* ImageViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ImageViewController.swift; sourceTree = "<group>"; };
+		5442E22725FC51E200A26F43 /* MultiPanelController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MultiPanelController.swift; sourceTree = "<group>"; };
+		5442E22B25FC521F00A26F43 /* SettingsViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SettingsViewController.swift; sourceTree = "<group>"; };
+		5442E22F25FC525200A26F43 /* TabBarViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TabBarViewController.swift; sourceTree = "<group>"; };
+		5442E23325FC528400A26F43 /* DetailViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DetailViewController.swift; sourceTree = "<group>"; };
+		5442E23925FC52CD00A26F43 /* ModalViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ModalViewController.swift; sourceTree = "<group>"; };
+		5442E23F25FC533800A26F43 /* DebugTableViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DebugTableViewController.swift; sourceTree = "<group>"; };
+		5442E24325FC538200A26F43 /* InspectorViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = InspectorViewController.swift; sourceTree = "<group>"; };
+		5442E24925FC53C100A26F43 /* DebugTextViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DebugTextViewController.swift; sourceTree = "<group>"; };
+		5442E25125FC541700A26F43 /* NestedScrollViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NestedScrollViewController.swift; sourceTree = "<group>"; };
+		54496C58263A7E5A0031E0C8 /* UseCaseController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UseCaseController.swift; sourceTree = "<group>"; };
 		545DB9EA21511E6300CA77B8 /* Samples.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Samples.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		545DB9ED21511E6300CA77B8 /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
-		545DB9EF21511E6300CA77B8 /* ViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ViewController.swift; sourceTree = "<group>"; };
+		545DB9EF21511E6300CA77B8 /* MainViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MainViewController.swift; sourceTree = "<group>"; };
 		545DB9F221511E6300CA77B8 /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/Main.storyboard; sourceTree = "<group>"; };
 		545DB9F421511E6400CA77B8 /* Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Assets.xcassets; sourceTree = "<group>"; };
 		545DB9F721511E6400CA77B8 /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/LaunchScreen.storyboard; sourceTree = "<group>"; };
@@ -65,9 +91,13 @@
 		545DBA0921511E6400CA77B8 /* SamplesUITests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = SamplesUITests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		545DBA0D21511E6400CA77B8 /* SampleUITests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SampleUITests.swift; sourceTree = "<group>"; };
 		545DBA0F21511E6400CA77B8 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
+		546341A025C6415100CA0596 /* UseCase.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UseCase.swift; sourceTree = "<group>"; };
+		546341AB25C6426500CA0596 /* CustomState.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CustomState.swift; sourceTree = "<group>"; };
 		549D23CA233C7779008EF4D7 /* FloatingPanel.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = FloatingPanel.framework; sourceTree = BUILT_PRODUCTS_DIR; };
-		54B51115216AFE5F0033A6F3 /* UIExtensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UIExtensions.swift; sourceTree = "<group>"; };
-		54CDC5D7215BBE23007D205C /* UIComponents.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UIComponents.swift; sourceTree = "<group>"; };
+		54B51115216AFE5F0033A6F3 /* Extensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Extensions.swift; sourceTree = "<group>"; };
+		54CDC5D7215BBE23007D205C /* Components.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Components.swift; sourceTree = "<group>"; };
+		54EAD35A263A75EB006A36EA /* Layouts.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Layouts.swift; sourceTree = "<group>"; };
+		54EAD364263A765F006A36EA /* PagePanelController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PagePanelController.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -96,6 +126,23 @@
 /* End PBXFrameworksBuildPhase section */
 
 /* Begin PBXGroup section */
+		5442E22225FC519700A26F43 /* ViewControllers */ = {
+			isa = PBXGroup;
+			children = (
+				5442E23F25FC533800A26F43 /* DebugTableViewController.swift */,
+				5442E24925FC53C100A26F43 /* DebugTextViewController.swift */,
+				5442E23325FC528400A26F43 /* DetailViewController.swift */,
+				5442E24325FC538200A26F43 /* InspectorViewController.swift */,
+				5442E22325FC51AF00A26F43 /* ImageViewController.swift */,
+				5442E25125FC541700A26F43 /* NestedScrollViewController.swift */,
+				5442E23925FC52CD00A26F43 /* ModalViewController.swift */,
+				5442E22725FC51E200A26F43 /* MultiPanelController.swift */,
+				5442E22B25FC521F00A26F43 /* SettingsViewController.swift */,
+				5442E22F25FC525200A26F43 /* TabBarViewController.swift */,
+			);
+			path = ViewControllers;
+			sourceTree = "<group>";
+		};
 		545DB9E121511E6300CA77B8 = {
 			isa = PBXGroup;
 			children = (
@@ -124,9 +171,13 @@
 				545DB9F621511E6400CA77B8 /* LaunchScreen.storyboard */,
 				545DB9F121511E6300CA77B8 /* Main.storyboard */,
 				545DB9ED21511E6300CA77B8 /* AppDelegate.swift */,
-				545DB9EF21511E6300CA77B8 /* ViewController.swift */,
-				54B51115216AFE5F0033A6F3 /* UIExtensions.swift */,
-				54CDC5D7215BBE23007D205C /* UIComponents.swift */,
+				545DB9EF21511E6300CA77B8 /* MainViewController.swift */,
+				54496C58263A7E5A0031E0C8 /* UseCaseController.swift */,
+				546341AA25C6421000CA0596 /* UseCases */,
+				5442E22225FC519700A26F43 /* ViewControllers */,
+				54EAD35A263A75EB006A36EA /* Layouts.swift */,
+				54B51115216AFE5F0033A6F3 /* Extensions.swift */,
+				54CDC5D7215BBE23007D205C /* Components.swift */,
 				545DB9F921511E6400CA77B8 /* Info.plist */,
 			);
 			path = Sources;
@@ -150,6 +201,16 @@
 			path = UITests;
 			sourceTree = "<group>";
 		};
+		546341AA25C6421000CA0596 /* UseCases */ = {
+			isa = PBXGroup;
+			children = (
+				546341A025C6415100CA0596 /* UseCase.swift */,
+				546341AB25C6426500CA0596 /* CustomState.swift */,
+				54EAD364263A765F006A36EA /* PagePanelController.swift */,
+			);
+			path = UseCases;
+			sourceTree = "<group>";
+		};
 /* End PBXGroup section */
 
 /* Begin PBXNativeTarget section */
@@ -303,10 +364,25 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				54CDC5D8215BBE23007D205C /* UIComponents.swift in Sources */,
-				54B51116216AFE5F0033A6F3 /* UIExtensions.swift in Sources */,
-				545DB9F021511E6300CA77B8 /* ViewController.swift in Sources */,
+				5442E23425FC528400A26F43 /* DetailViewController.swift in Sources */,
+				54496C59263A7E5A0031E0C8 /* UseCaseController.swift in Sources */,
+				54CDC5D8215BBE23007D205C /* Components.swift in Sources */,
+				54B51116216AFE5F0033A6F3 /* Extensions.swift in Sources */,
+				5442E24A25FC53C100A26F43 /* DebugTextViewController.swift in Sources */,
+				546341AC25C6426500CA0596 /* CustomState.swift in Sources */,
+				5442E23A25FC52CD00A26F43 /* ModalViewController.swift in Sources */,
+				5442E22425FC51AF00A26F43 /* ImageViewController.swift in Sources */,
+				5442E24025FC533800A26F43 /* DebugTableViewController.swift in Sources */,
+				5442E25225FC541700A26F43 /* NestedScrollViewController.swift in Sources */,
+				5442E22825FC51E200A26F43 /* MultiPanelController.swift in Sources */,
+				546341A125C6415100CA0596 /* UseCase.swift in Sources */,
+				545DB9F021511E6300CA77B8 /* MainViewController.swift in Sources */,
 				545DB9EE21511E6300CA77B8 /* AppDelegate.swift in Sources */,
+				5442E23025FC525200A26F43 /* TabBarViewController.swift in Sources */,
+				54EAD35B263A75EB006A36EA /* Layouts.swift in Sources */,
+				54EAD365263A765F006A36EA /* PagePanelController.swift in Sources */,
+				5442E24425FC538200A26F43 /* InspectorViewController.swift in Sources */,
+				5442E22C25FC521F00A26F43 /* SettingsViewController.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

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

@@ -1,11 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="17156" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="RoN-h0-uBD">
-    <device id="retina5_9" orientation="portrait" appearance="light"/>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="17701" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="RoN-h0-uBD">
     <dependencies>
-        <deployment identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="17125"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="17703"/>
         <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>
@@ -28,24 +27,24 @@
         <!--Samples-->
         <scene sceneID="35L-Gs-Vts">
             <objects>
-                <viewController id="jF4-A0-Eq6" customClass="SampleListViewController" customModule="Samples" customModuleProvider="target" sceneMemberID="viewController">
+                <viewController id="jF4-A0-Eq6" customClass="MainViewController" customModule="Samples" customModuleProvider="target" sceneMemberID="viewController">
                     <view key="view" contentMode="scaleToFill" id="Smh-Bd-AAc">
-                        <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
+                        <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <tableView clipsSubviews="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" dataMode="prototypes" style="plain" separatorStyle="default" rowHeight="-1" estimatedRowHeight="-1" sectionHeaderHeight="28" sectionFooterHeight="28" translatesAutoresizingMaskIntoConstraints="NO" id="7IS-PU-x0P">
-                                <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
+                                <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
                                 <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                                 <prototypes>
                                     <tableViewCell clipsSubviews="YES" contentMode="scaleToFill" preservesSuperviewLayoutMargins="YES" selectionStyle="default" indentationWidth="10" reuseIdentifier="Cell" textLabel="M0G-C8-hAO" style="IBUITableViewCellStyleDefault" id="ySY-oA-g81">
-                                        <rect key="frame" x="0.0" y="28" width="375" height="43.666667938232422"/>
+                                        <rect key="frame" x="0.0" y="28" width="600" height="43.5"/>
                                         <autoresizingMask key="autoresizingMask"/>
                                         <tableViewCellContentView key="contentView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" preservesSuperviewLayoutMargins="YES" insetsLayoutMarginsFromSafeArea="NO" tableViewCell="ySY-oA-g81" id="sXB-nH-2g2">
-                                            <rect key="frame" x="0.0" y="0.0" width="375" height="43.666667938232422"/>
+                                            <rect key="frame" x="0.0" y="0.0" width="600" height="43.5"/>
                                             <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="16" y="0.0" width="343" height="43.666667938232422"/>
+                                                    <rect key="frame" x="16" y="0.0" width="568" height="43.5"/>
                                                     <autoresizingMask key="autoresizingMask"/>
                                                     <fontDescription key="fontDescription" type="system" pointSize="17"/>
                                                     <nil key="textColor"/>
@@ -86,23 +85,23 @@
             <objects>
                 <viewController storyboardIdentifier="SettingsViewController" id="C1X-9Z-TyQ" customClass="SettingsViewController" customModule="Samples" customModuleProvider="target" sceneMemberID="viewController">
                     <view key="view" contentMode="scaleToFill" insetsLayoutMarginsFromSafeArea="NO" id="af9-Zr-Ppc">
-                        <rect key="frame" x="0.0" y="0.0" width="375" height="197.33333333333334"/>
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="197.33000000000001"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <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"/>
+                                <rect key="frame" x="32" y="16" width="311" height="149.5"/>
                                 <subviews>
                                     <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"/>
+                                        <rect key="frame" x="0.0" y="0.0" width="311" height="53"/>
                                         <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="17.333333333333332"/>
+                                                <rect key="frame" x="118.5" y="0.0" width="74.5" height="17.5"/>
                                                 <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"/>
+                                                <rect key="frame" x="78.5" y="25.5" width="154.5" height="27.5"/>
                                                 <fontDescription key="fontDescription" style="UICTFontTextStyleTitle2"/>
                                                 <nil key="textColor"/>
                                                 <nil key="highlightedColor"/>
@@ -110,19 +109,19 @@
                                         </subviews>
                                     </stackView>
                                     <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"/>
+                                        <rect key="frame" x="0.0" y="69" width="311" height="80.5"/>
                                         <subviews>
                                             <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"/>
+                                                        <rect key="frame" x="0.0" y="5.5" width="254" height="20.5"/>
                                                         <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"/>
+                                                        <rect key="frame" x="262" y="0.5" width="51" height="31"/>
                                                         <connections>
                                                             <action selector="toggleLargeTitle:" destination="C1X-9Z-TyQ" eventType="valueChanged" id="FJS-Ty-mCY"/>
                                                         </connections>
@@ -130,16 +129,16 @@
                                                 </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"/>
+                                                <rect key="frame" x="0.0" y="48" width="311" height="32.5"/>
                                                 <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"/>
+                                                        <rect key="frame" x="0.0" y="6" width="254" height="20.5"/>
                                                         <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"/>
+                                                        <rect key="frame" x="262" y="0.5" width="51" height="31"/>
                                                         <connections>
                                                             <action selector="toggleTranslucent:" destination="C1X-9Z-TyQ" eventType="valueChanged" id="nL4-3L-9hh"/>
                                                         </connections>
@@ -176,11 +175,11 @@
             <objects>
                 <viewController id="RpE-lI-27a" customClass="TabBarContentViewController" customModule="Samples" customModuleProvider="target" sceneMemberID="viewController">
                     <view key="view" contentMode="scaleToFill" id="JER-jz-KSq">
-                        <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
+                        <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <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"/>
+                                <rect key="frame" x="20" y="0.0" width="39" height="30"/>
                                 <state key="normal" title="Close"/>
                                 <connections>
                                     <action selector="closeWithSender:" destination="RpE-lI-27a" eventType="touchUpInside" id="hj3-Xv-6Gq"/>
@@ -207,11 +206,11 @@
             <objects>
                 <viewController id="pOk-Zm-vD9" customClass="TabBarContentViewController" customModule="Samples" customModuleProvider="target" sceneMemberID="viewController">
                     <view key="view" contentMode="scaleToFill" id="85d-ub-G8k">
-                        <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
+                        <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <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"/>
+                                <rect key="frame" x="20" y="0.0" width="39" height="30"/>
                                 <state key="normal" title="Close"/>
                                 <connections>
                                     <action selector="closeWithSender:" destination="pOk-Zm-vD9" eventType="touchUpInside" id="111-PD-Pop"/>
@@ -238,11 +237,11 @@
             <objects>
                 <viewController id="lto-Zc-Vtp" customClass="TabBarContentViewController" customModule="Samples" customModuleProvider="target" sceneMemberID="viewController">
                     <view key="view" contentMode="scaleToFill" id="ji9-Ez-N7i">
-                        <rect key="frame" x="0.0" y="0.0" width="375" height="812"/>
+                        <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <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"/>
+                                <rect key="frame" x="20" y="0.0" width="39" height="30"/>
                                 <state key="normal" title="Close"/>
                                 <connections>
                                     <action selector="closeWithSender:" destination="bYI-y3-Rzb" eventType="touchUpInside" id="YL4-GP-ZEZ"/>
@@ -273,7 +272,7 @@
                         <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="125.66666666666669" y="24" width="124" height="20.333333333333329"/>
+                                <rect key="frame" x="125.5" y="24" width="124" height="20.5"/>
                                 <fontDescription key="fontDescription" type="system" pointSize="17"/>
                                 <nil key="textColor"/>
                                 <nil key="highlightedColor"/>
@@ -293,6 +292,71 @@
             </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>
@@ -317,11 +381,11 @@
             <objects>
                 <viewController storyboardIdentifier="ModalViewController" id="bYI-y3-Rzb" customClass="ModalViewController" customModule="Samples" customModuleProvider="target" sceneMemberID="viewController">
                     <view key="view" contentMode="scaleToFill" id="qwo-GK-p1U">
-                        <rect key="frame" x="0.0" y="0.0" width="375" height="724"/>
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="778"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <view contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="vut-mK-Y4t" customClass="SafeAreaView" customModule="Samples" customModuleProvider="target">
-                                <rect key="frame" x="0.0" y="724" width="375" height="0.0"/>
+                                <rect key="frame" x="0.0" y="758" 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="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="sbF-Az-7sy">
@@ -332,7 +396,7 @@
                                 </connections>
                             </button>
                             <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"/>
+                                <rect key="frame" x="134.5" y="88" width="106" height="326"/>
                                 <subviews>
                                     <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"/>
@@ -532,11 +596,11 @@
                                 </constraints>
                             </view>
                             <view alpha="0.5" contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="Kva-Z7-0qY" customClass="OnSafeAreaView" customModule="Samples" customModuleProvider="target">
-                                <rect key="frame" x="0.0" y="44" width="375" height="734"/>
+                                <rect key="frame" x="0.0" y="0.0" width="375" height="778"/>
                                 <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="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"/>
+                                <rect key="frame" x="319" y="0.0" width="44" height="44"/>
                                 <constraints>
                                     <constraint firstAttribute="height" constant="44" id="0jg-5D-A1F"/>
                                     <constraint firstAttribute="width" constant="44" id="1Cq-PA-wgW"/>
@@ -546,10 +610,10 @@
                                 </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" height="31"/>
+                                <rect key="frame" x="8" y="8" 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" height="20.333333333333332"/>
+                                        <rect key="frame" x="0.0" y="5.5" width="91" height="20.5"/>
                                         <fontDescription key="fontDescription" type="system" pointSize="17"/>
                                         <nil key="textColor"/>
                                         <nil key="highlightedColor"/>
@@ -563,7 +627,7 @@
                                 </subviews>
                             </stackView>
                             <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"/>
+                                <rect key="frame" x="130.5" y="88" width="114" height="134"/>
                                 <subviews>
                                     <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"/>
@@ -717,12 +781,22 @@ 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/Components.swift

@@ -3,7 +3,7 @@
 import UIKit
 
 @IBDesignable
-class CloseButton: UIButton {
+final class CloseButton: UIButton {
     required init?(coder aDecoder: NSCoder) {
         super.init(coder: aDecoder)
         render()
@@ -71,7 +71,7 @@ class CloseButton: UIButton {
 }
 
 @IBDesignable
-class SafeAreaView: UIView {
+final class SafeAreaView: UIView {
     override func prepareForInterfaceBuilder() {
         let label = UILabel()
         label.text = "Safe Area"
@@ -86,7 +86,7 @@ class SafeAreaView: UIView {
 
 
 @IBDesignable
-class OnSafeAreaView: UIView {
+final class OnSafeAreaView: UIView {
     override func prepareForInterfaceBuilder() {
         let label = UILabel()
         label.text = "On Safe Area"

Examples/Samples/Sources/Layouts.swift

@@ -0,0 +1,90 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+/**
+ - Attention: `FloatingPanelLayout` must not be applied by the parent view
+ controller of a panel. But here `MainViewController` adopts it
+ purposely to check if the library prints an appropriate warning.
+ */
+extension MainViewController: FloatingPanelLayout {
+    var position: FloatingPanelPosition { .bottom }
+    var initialState: FloatingPanelState { .half }
+    var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: UIScreen.main.bounds.height == 667.0 ? 18.0 : 16.0, edge: .top, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 262.0, edge: .bottom, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 69.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
+    }
+}
+
+class TopPositionedPanelLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition = .top
+    let initialState: FloatingPanelState = .full
+
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 88.0, edge: .bottom, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 216.0, edge: .top, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .top, referenceGuide: .safeArea)
+        ]
+    }
+}
+
+class IntrinsicPanelLayout: FloatingPanelBottomLayout {
+    override var initialState: FloatingPanelState { .full }
+    override var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.0, referenceGuide: .safeArea)
+        ]
+    }
+}
+
+class RemovablePanelLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .half
+
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.0, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 130.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
+    }
+
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return 0.3
+    }
+}
+
+class RemovablePanelLandscapeLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .full
+
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.0, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 216.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
+    }
+
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return 0.3
+    }
+}
+
+class ModalPanelLayout: FloatingPanelLayout {
+    let position: FloatingPanelPosition = .bottom
+    let initialState: FloatingPanelState = .full
+
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 0.0, referenceGuide: .safeArea),
+        ]
+    }
+
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        return 0.3
+    }
+}

Examples/Samples/Sources/MainViewController.swift

@@ -0,0 +1,93 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+final class MainViewController: UIViewController {
+    @IBOutlet weak var tableView: UITableView!
+    private var observations: [NSKeyValueObservation] = []
+
+    private lazy var useCaseController = UseCaseController(mainVC: self)
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        tableView.dataSource = self
+        tableView.delegate = self
+        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell")
+        automaticallyAdjustsScrollViewInsets = false
+
+        let searchController = UISearchController(searchResultsController: nil)
+        if #available(iOS 11.0, *) {
+            navigationItem.searchController = searchController
+            navigationItem.hidesSearchBarWhenScrolling = false
+            navigationItem.largeTitleDisplayMode = .automatic
+        } else {
+            // Fallback on earlier versions
+        }
+        var insets = UIEdgeInsets.zero
+        insets.bottom += 69.0
+        tableView.contentInset = insets
+
+        // Show the initial panel
+        useCaseController.set(useCase: .trackingTableView)
+    }
+
+    override func viewDidAppear(_ animated: Bool) {
+        super.viewDidAppear(animated)
+        if #available(iOS 11.0, *) {
+            if let observation = navigationController?.navigationBar.observe(\.prefersLargeTitles, changeHandler: { (bar, _) in
+                self.tableView.reloadData()
+            }) {
+                observations.append(observation)
+            }
+        }
+    }
+
+    override func viewWillDisappear(_ animated: Bool) {
+        super.viewWillDisappear(animated)
+        observations.removeAll()
+    }
+
+    // MARK:- Actions
+    @IBAction func showDebugMenu(_ sender: UIBarButtonItem) {
+        useCaseController.setUpSettingsPanel(for: self)
+    }
+}
+
+extension MainViewController: UITableViewDataSource {
+    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
+        if #available(iOS 11.0, *) {
+            if navigationController?.navigationBar.prefersLargeTitles == true {
+                return UseCase.allCases.count + 30
+            } else {
+                return UseCase.allCases.count
+            }
+        } else {
+            return UseCase.allCases.count
+        }
+    }
+
+    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
+        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
+        if UseCase.allCases.count > indexPath.row {
+            let menu = UseCase.allCases[indexPath.row]
+            cell.textLabel?.text = menu.name
+        } else {
+            cell.textLabel?.text = "\(indexPath.row) row"
+        }
+        return cell
+    }
+}
+
+extension MainViewController: UITableViewDelegate {
+    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
+        guard UseCase.allCases.count > indexPath.row else { return }
+
+        // Change panels
+        useCaseController.set(useCase: UseCase.allCases[indexPath.row])
+    }
+
+    @objc func dismissPresentedVC() {
+        self.presentedViewController?.dismiss(animated: true, completion: nil)
+    }
+}

Examples/Samples/Sources/UseCaseController.swift

@@ -0,0 +1,329 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+final class UseCaseController: NSObject {
+    unowned let mainVC: MainViewController
+    private(set) var useCase: UseCase = .trackingTableView
+
+    fileprivate var mainPanelVC: FloatingPanelController!
+    private var detailPanelVC: FloatingPanelController!
+    private var settingsPanelVC: FloatingPanelController!
+
+    private lazy var pagePanelController = PagePanelController()
+
+    private var mainPanelObserves: [NSKeyValueObservation] = []
+
+    init(mainVC: MainViewController) {
+        self.mainVC = mainVC
+    }
+
+    func set(useCase: UseCase) {
+        self.useCase = useCase
+
+        let contentVC = useCase.makeContentViewController(with: mainVC.storyboard!)
+
+        detailPanelVC?.removePanelFromParent(animated: true, completion: nil)
+        detailPanelVC = nil
+
+        switch useCase {
+        case .showDetail:
+            detailPanelVC?.removePanelFromParent(animated: false)
+
+            // Initialize FloatingPanelController
+            detailPanelVC = FloatingPanelController()
+            detailPanelVC.delegate = self
+
+            let appearance = SurfaceAppearance()
+            appearance.cornerRadius = 6.0
+            detailPanelVC.surfaceView.appearance = appearance
+
+            // Set a content view controller
+            detailPanelVC.set(contentViewController: contentVC)
+
+            detailPanelVC.contentMode = .fitToBounds
+            (contentVC as? DetailViewController)?.intrinsicHeightConstraint.isActive = false
+
+            //  Add FloatingPanel to self.view
+            detailPanelVC.addPanel(toParent: mainVC, animated: true)
+        case .showModal, .showTabBar:
+            let modalVC = contentVC
+            modalVC.modalPresentationStyle = .fullScreen
+            mainVC.present(modalVC, animated: true, completion: nil)
+
+        case .showPageView:
+            let pageVC = pagePanelController.makePageViewController(for: mainVC)
+            mainVC.present(pageVC, animated: true, completion: nil)
+
+        case .showPageContentView:
+            let pageVC = pagePanelController.makePageViewControllerForContent()
+            self.addMainPanel(with: pageVC)
+        case .showPanelModal:
+            let fpc = FloatingPanelController()
+            let contentVC = mainVC.storyboard!.instantiateViewController(withIdentifier: "DetailViewController")
+            contentVC.loadViewIfNeeded()
+            (contentVC as? DetailViewController)?.modeChangeView.isHidden = true
+            fpc.set(contentViewController: contentVC)
+            fpc.delegate = self
+
+            let appearance = SurfaceAppearance()
+            appearance.cornerRadius = 38.5
+            fpc.surfaceView.appearance = appearance
+            fpc.backdropView.dismissalTapGestureRecognizer.isEnabled = true
+
+            fpc.isRemovalInteractionEnabled = true
+
+            mainVC.present(fpc, animated: true, completion: nil)
+
+        case .showMultiPanelModal:
+            let fpc = MultiPanelController()
+            mainVC.present(fpc, animated: true, completion: nil)
+
+        case .showPanelInSheetModal:
+            let fpc = FloatingPanelController()
+            let contentVC = UIViewController()
+            fpc.set(contentViewController: contentVC)
+            fpc.delegate = self
+
+            let apprearance = SurfaceAppearance()
+            apprearance.cornerRadius = 38.5
+            apprearance.shadows = []
+            fpc.surfaceView.appearance = apprearance
+            fpc.isRemovalInteractionEnabled = true
+
+            let mvc = UIViewController()
+            mvc.view.backgroundColor = UIColor(displayP3Red: 2/255, green: 184/255, blue: 117/255, alpha: 1.0)
+            fpc.addPanel(toParent: mvc)
+            mainVC.present(mvc, animated: true, completion: nil)
+        case .showContentInset:
+            let contentViewController = UIViewController()
+            contentViewController.view.backgroundColor = .green
+
+            let fpc = FloatingPanelController()
+            fpc.set(contentViewController: contentViewController)
+            fpc.surfaceView.contentPadding = .init(top: 20, left: 20, bottom: 20, right: 20)
+
+            fpc.delegate = self
+            fpc.isRemovalInteractionEnabled = true
+            mainVC.present(fpc, animated: true, completion: nil)
+
+        case .showContainerMargins:
+            let fpc = FloatingPanelController()
+
+            let appearance = SurfaceAppearance()
+            appearance.cornerRadius = 38.5
+            fpc.surfaceView.appearance = appearance
+
+            fpc.surfaceView.backgroundColor = .red
+            fpc.surfaceView.containerMargins = .init(top: 24.0, left: 8.0, bottom: max(mainVC.layoutInsets.bottom, 8.0), right: 8.0)
+            #if swift(>=5.1) // Actually Xcode 11 or later
+            if #available(iOS 13.0, *) {
+                fpc.surfaceView.layer.cornerCurve = .continuous
+            }
+            #endif
+
+            fpc.delegate = self
+            fpc.isRemovalInteractionEnabled = true
+            mainVC.present(fpc, animated: true, completion: nil)
+        default:
+            self.addMainPanel(with: contentVC)
+        }
+    }
+
+    private func addMainPanel(with contentVC: UIViewController) {
+        mainPanelObserves.removeAll()
+
+        let oldMainPanelVC = mainPanelVC
+
+        mainPanelVC = FloatingPanelController()
+        mainPanelVC.delegate = self
+        mainPanelVC.contentInsetAdjustmentBehavior = .always
+
+        let appearance = SurfaceAppearance()
+        appearance.cornerRadius = 6.0
+        mainPanelVC.surfaceView.appearance = appearance
+
+        set(contentViewController: contentVC)
+
+        useCase.setUpInteraction(for: self)
+
+        //  Add FloatingPanel to self.view
+        if let oldMainPanelVC = oldMainPanelVC {
+            oldMainPanelVC.removePanelFromParent(animated: true, completion: {
+                self.mainPanelVC.addPanel(toParent: self.mainVC, animated: true)
+            })
+        } else {
+            mainPanelVC.addPanel(toParent: mainVC, animated: true)
+        }
+    }
+
+    private func set(contentViewController contentVC: UIViewController) {
+        mainPanelVC.set(contentViewController: contentVC)
+        // Track a scroll view
+        switch contentVC {
+        case let consoleVC as DebugTextViewController:
+            mainPanelVC.track(scrollView: consoleVC.textView)
+
+        case let contentVC as DebugTableViewController:
+            let ob = contentVC.tableView.observe(\.isEditing) { (tableView, _) in
+                self.mainPanelVC.panGestureRecognizer.isEnabled = !tableView.isEditing
+            }
+            mainPanelObserves.append(ob)
+            mainPanelVC.track(scrollView: contentVC.tableView)
+        case let contentVC as NestedScrollViewController:
+            mainPanelVC.track(scrollView: contentVC.scrollView)
+        case let navVC as UINavigationController:
+            if let rootVC = (navVC.topViewController as? MainViewController) {
+                rootVC.loadViewIfNeeded()
+                mainPanelVC.track(scrollView: rootVC.tableView)
+            }
+        case let contentVC as ImageViewController:
+            if #available(iOS 11.0, *) {
+                let mode: ImageViewController.Mode = (useCase == .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
+        }
+    }
+
+    @objc
+    fileprivate func handleSurface(tapGesture: UITapGestureRecognizer) {
+        switch mainPanelVC.state {
+        case .full:
+            mainPanelVC.move(to: .half, animated: true)
+        default:
+            mainPanelVC.move(to: .full, animated: true)
+        }
+    }
+
+    func setUpSettingsPanel(for mainVC: MainViewController) {
+        guard settingsPanelVC == nil else { return }
+        // Initialize FloatingPanelController
+        settingsPanelVC = FloatingPanelController()
+
+        let appearance = SurfaceAppearance()
+        appearance.cornerRadius = 6.0
+        settingsPanelVC.surfaceView.appearance = appearance
+
+        settingsPanelVC.isRemovalInteractionEnabled = true
+        settingsPanelVC.backdropView.dismissalTapGestureRecognizer.isEnabled = true
+        settingsPanelVC.delegate = self
+
+        let contentVC = mainVC.storyboard?.instantiateViewController(withIdentifier: "SettingsViewController")
+
+        // Set a content view controller
+        settingsPanelVC.set(contentViewController: contentVC)
+
+        //  Add FloatingPanel to self.view
+        settingsPanelVC.addPanel(toParent: mainVC, animated: true)
+    }
+}
+
+extension UseCaseController: FloatingPanelControllerDelegate {
+    func floatingPanel(_ vc: FloatingPanelController, contentOffsetForPinning trackingScrollView: UIScrollView) -> CGPoint {
+        if useCase == .showNavigationController, #available(iOS 11.0, *) {
+            // 148.0 is the SafeArea's top value for a navigation bar with a large title.
+            return CGPoint(x: 0.0, y: 0.0 - trackingScrollView.contentInset.top - 148.0)
+        }
+        return CGPoint(x: 0.0, y: 0.0 - trackingScrollView.contentInset.top)
+    }
+
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+        if vc == settingsPanelVC {
+            return IntrinsicPanelLayout()
+        }
+
+        switch useCase {
+        case .showTopPositionedPanel:
+            return TopPositionedPanelLayout()
+        case .showRemovablePanel:
+            return newCollection.verticalSizeClass == .compact ? RemovablePanelLandscapeLayout() :  RemovablePanelLayout()
+        case .showIntrinsicView:
+            return IntrinsicPanelLayout()
+        case .showPanelModal:
+            if vc != mainPanelVC && vc != detailPanelVC {
+                return ModalPanelLayout()
+            }
+            fallthrough
+        case .showContentInset:
+            return FloatingPanelBottomLayout()
+        case .showCustomStatePanel:
+            return FloatingPanelLayoutWithCustomState()
+        default:
+            return (newCollection.verticalSizeClass == .compact) ? FloatingPanelBottomLayout() : mainVC
+        }
+    }
+
+    func floatingPanelDidRemove(_ vc: FloatingPanelController) {
+        switch vc {
+        case settingsPanelVC:
+            settingsPanelVC = nil
+        default:
+            break
+        }
+    }
+}
+
+extension UseCaseController: UIGestureRecognizerDelegate {
+    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+        switch useCase {
+        case .showNestedScrollView:
+            return true
+        default:
+            return false
+        }
+    }
+    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+        return false
+    }
+}
+
+extension UseCase {
+    func makeContentViewController(with storyboard: UIStoryboard) -> UIViewController {
+        guard let storyboardID = self.storyboardID else { return DebugTableViewController() }
+        return storyboard.instantiateViewController(withIdentifier: storyboardID)
+    }
+
+    func setUpInteraction(for useCaseController: UseCaseController) {
+        let mainVC = useCaseController.mainVC
+        let mainPanelVC = useCaseController.mainPanelVC!
+
+        // Enable tap-to-hide and removal interaction
+        switch self {
+        case .trackingTableView:
+            let tapGesture = UITapGestureRecognizer(target: useCaseController, action: #selector(UseCaseController.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 = useCaseController
+        case .showPageContentView:
+            if let page = (mainPanelVC.contentViewController as? UIPageViewController)?.viewControllers?.first {
+                mainPanelVC.track(scrollView: (page as! DebugTableViewController).tableView)
+            }
+        case .showRemovablePanel, .showIntrinsicView:
+            mainPanelVC.isRemovalInteractionEnabled = true
+            mainPanelVC.backdropView.dismissalTapGestureRecognizer.isEnabled = true
+        case .showNavigationController:
+            mainPanelVC.contentInsetAdjustmentBehavior = .never
+        case .showTopPositionedPanel: // For debug
+            let contentVC = UIViewController()
+            contentVC.view.backgroundColor = .red
+            mainPanelVC.set(contentViewController: contentVC)
+            mainPanelVC.addPanel(toParent: mainVC, animated: true)
+            return
+        default:
+            break
+        }
+    }
+}

Examples/Samples/Sources/UseCases/CustomState.swift

@@ -0,0 +1,22 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import Foundation
+import FloatingPanel
+
+extension FloatingPanelState {
+    static let lastQuart: FloatingPanelState = FloatingPanelState(rawValue: "lastQuart", order: 750)
+    static let firstQuart: FloatingPanelState = FloatingPanelState(rawValue: "firstQuart", order: 250)
+}
+
+class FloatingPanelLayoutWithCustomState: FloatingPanelBottomLayout {
+    override var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .top, referenceGuide: .safeArea),
+            .lastQuart: FloatingPanelLayoutAnchor(fractionalInset: 0.75, edge: .bottom, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
+            .firstQuart: FloatingPanelLayoutAnchor(fractionalInset: 0.25, edge: .bottom, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 20.0, edge: .bottom, referenceGuide: .safeArea),
+        ]
+    }
+}
+

Examples/Samples/Sources/UseCases/PagePanelController.swift

@@ -0,0 +1,82 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+final class PagePanelController: NSObject {
+    lazy var pages = [UIColor.blue, .red, .green].compactMap({ (color) -> UIViewController in
+        let page = FloatingPanelController(delegate: self)
+        page.view.backgroundColor = color
+        page.panGestureRecognizer.delegateProxy = self
+        page.show()
+        return page
+    })
+
+    func makePageViewControllerForContent() -> UIPageViewController {
+        pages = [DebugTableViewController(), DebugTableViewController(), DebugTableViewController()]
+        let pageVC = UIPageViewController(transitionStyle: .scroll, navigationOrientation: .horizontal, options: [:])
+        pageVC.dataSource = self
+        pageVC.delegate = self
+        pageVC.setViewControllers([pages[0]], direction: .forward, animated: false, completion: nil)
+        return pageVC
+    }
+
+    func makePageViewController(for vc: MainViewController) -> UIPageViewController {
+        let pageVC = UIPageViewController(transitionStyle: .scroll, navigationOrientation: .horizontal, options: [:])
+        let closeButton = UIButton(type: .custom)
+        pageVC.view.addSubview(closeButton)
+        closeButton.setTitle("Close", for: .normal)
+        closeButton.translatesAutoresizingMaskIntoConstraints = false
+        closeButton.addTarget(vc, action: #selector(MainViewController.dismissPresentedVC), for: .touchUpInside)
+        NSLayoutConstraint.activate([
+            closeButton.topAnchor.constraint(equalTo: pageVC.layoutGuide.topAnchor, constant: 16.0),
+            closeButton.leftAnchor.constraint(equalTo: pageVC.view.leftAnchor, constant: 16.0),
+            ])
+        pageVC.dataSource = self
+        pageVC.setViewControllers([pages[0]], direction: .forward, animated: false, completion: nil)
+        pageVC.modalPresentationStyle = .fullScreen
+        return pageVC
+    }
+}
+
+extension PagePanelController: FloatingPanelControllerDelegate {
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+        return FloatingPanelBottomLayout()
+    }
+}
+
+extension PagePanelController: UIGestureRecognizerDelegate {
+    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+        return true
+    }
+    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
+        return false
+    }
+}
+
+
+extension PagePanelController: UIPageViewControllerDataSource {
+    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
+        guard
+            let index = pages.firstIndex(of: viewController),
+            index + 1 < pages.count
+            else { return nil }
+        return pages[index + 1]
+    }
+    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
+        guard
+            let index = pages.firstIndex(of: viewController),
+            index - 1 >= 0
+            else { return nil }
+        return pages[index - 1]
+    }
+}
+
+extension PagePanelController: UIPageViewControllerDelegate {
+    // For showPageContent
+    func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
+        if completed, let page = pageViewController.viewControllers?.first {
+            (pageViewController.parent as! FloatingPanelController).track(scrollView: (page as! DebugTableViewController).tableView)
+        }
+    }
+}

Examples/Samples/Sources/UseCases/UseCase.swift

@@ -0,0 +1,78 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import Foundation
+
+enum UseCase: Int, CaseIterable {
+    case trackingTableView
+    case trackingTextView
+    case showDetail
+    case showModal
+    case showPanelModal
+    case showMultiPanelModal
+    case showPanelInSheetModal
+    case showTabBar
+    case showPageView
+    case showPageContentView
+    case showNestedScrollView
+    case showRemovablePanel
+    case showIntrinsicView
+    case showContentInset
+    case showContainerMargins
+    case showNavigationController
+    case showTopPositionedPanel
+    case showAdaptivePanel
+    case showAdaptivePanelWithCustomGuide
+    case showCustomStatePanel
+
+    var name: String {
+        switch self {
+        case .trackingTableView: return "Scroll tracking(TableView)"
+        case .trackingTextView: return "Scroll tracking(TextView)"
+        case .showDetail: return "Show Detail Panel"
+        case .showModal: return "Show Modal"
+        case .showPanelModal: return "Show Panel Modal"
+        case .showMultiPanelModal: return "Show Multi Panel Modal"
+        case .showPanelInSheetModal: return "Show Panel in Sheet Modal"
+        case .showTabBar: return "Show Tab Bar"
+        case .showPageView: return "Show Page View"
+        case .showPageContentView: return "Show Page Content View"
+        case .showNestedScrollView: return "Show Nested ScrollView"
+        case .showRemovablePanel: return "Show Removable Panel"
+        case .showIntrinsicView: return "Show Intrinsic View"
+        case .showContentInset: return "Show with ContentInset"
+        case .showContainerMargins: return "Show with ContainerMargins"
+        case .showNavigationController: return "Show Navigation Controller"
+        case .showTopPositionedPanel: return "Show Top Positioned Panel"
+        case .showAdaptivePanel: return "Show Adaptive Panel"
+        case .showAdaptivePanelWithCustomGuide: return "Show Adaptive Panel (Custom Layout Guide)"
+        case .showCustomStatePanel: return "Show Panel with Custom state"
+        }
+    }
+
+    var storyboardID: String? {
+        switch self {
+        case .trackingTableView: return nil
+        case .trackingTextView: return "ConsoleViewController" // Storyboard only
+        case .showDetail: return String(describing: DetailViewController.self)
+        case .showModal: return String(describing: ModalViewController.self)
+        case .showMultiPanelModal: return nil
+        case .showPanelInSheetModal: return nil
+        case .showPanelModal: return nil
+        case .showTabBar: return String(describing: TabBarViewController.self)
+        case .showPageView: return nil
+        case .showPageContentView: return nil
+        case .showNestedScrollView: return String(describing: NestedScrollViewController.self)
+        case .showRemovablePanel: return String(describing: DetailViewController.self)
+        case .showIntrinsicView: return "IntrinsicViewController" // Storyboard only
+        case .showContentInset: return nil
+        case .showContainerMargins: return nil
+        case .showNavigationController: return "RootNavigationController" // Storyboard only
+        case .showTopPositionedPanel: return nil
+        case .showAdaptivePanel,
+             .showAdaptivePanelWithCustomGuide:
+            return String(describing: ImageViewController.self)
+        case .showCustomStatePanel:
+            return nil
+        }
+    }
+}

Examples/Samples/Sources/ViewControllers/DebugTableViewController.swift

@@ -0,0 +1,272 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+class DebugTableViewController: InspectableViewController {
+    // MARK: - Views
+
+    lazy var tableView: UITableView = {
+        let tableView = UITableView(frame: .zero, style: .plain)
+        tableView.dataSource = self
+        tableView.delegate = self
+        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell")
+        return tableView
+    }()
+    lazy var buttonStackView: UIStackView = {
+        let stackView = UIStackView()
+        stackView.axis = .vertical
+        stackView.distribution = .fillEqually
+        stackView.alignment = .trailing
+        stackView.spacing = 10.0
+        return stackView
+    }()
+    private lazy var reorderButton: UIButton = {
+        let button = UIButton()
+        button.setTitle(Menu.reorder.rawValue, for: .normal)
+        button.setTitleColor(view.tintColor, for: .normal)
+        button.addTarget(self, action: #selector(reorderItems), for: .touchUpInside)
+        return button
+    }()
+    private lazy var trackingSwitchWrapper: UIStackView = {
+        let stackView = UIStackView()
+        stackView.axis = .horizontal
+        stackView.distribution = .fillProportionally
+        stackView.alignment = .center
+        stackView.spacing = 8.0
+        stackView.addArrangedSubview(trackingLabel)
+        stackView.addArrangedSubview(trackingSwitch)
+        return stackView
+    }()
+    private lazy var trackingLabel: UILabel = {
+        let label = UILabel()
+        label.text = "Tracking"
+        label.font = UIFont.systemFont(ofSize: 17.0, weight: .regular)
+        return label
+    }()
+    private lazy var trackingSwitch: UISwitch = {
+        let trackingSwitch = UISwitch()
+        trackingSwitch.isOn = true
+        trackingSwitch.addTarget(self, action: #selector(turnTrackingOn), for: .touchUpInside)
+        return trackingSwitch
+    }()
+
+    // MARK: - Properties
+
+    private lazy var items: [String] = {
+        let items = (0..<100).map { "Items \($0)" }
+        return Command.replace(items: items)
+    }()
+    private var itemHeight: CGFloat = 66.0
+
+    enum Menu: String, CaseIterable {
+        case turnOffTracking = "Tracking"
+        case reorder = "Reorder"
+    }
+
+    enum Command: Int, CaseIterable {
+        case animateScroll
+        case changeContentSize
+        case moveToFull
+        case moveToHalf
+        var text: String {
+            switch self {
+            case .animateScroll: return "Scroll in the middle"
+            case .changeContentSize: return "Change content size"
+            case .moveToFull: return "Move to Full"
+            case.moveToHalf: return "Move to Half"
+            }
+        }
+
+        static func replace(items: [String]) -> [String] {
+            return items.enumerated().map { (index, text) -> String in
+                if let action = Command(rawValue: index) {
+                    return "\(index). \(action.text)"
+                }
+                return text
+            }
+        }
+
+        func execute(for vc: DebugTableViewController) {
+            switch self {
+            case .animateScroll:
+                vc.animateScroll()
+            case .changeContentSize:
+                vc.changeContentSize()
+            case .moveToFull:
+                vc.moveToFull()
+            case .moveToHalf:
+                vc.moveToHalf()
+            }
+        }
+    }
+
+    // MARK: - Lifecycle
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        layoutTableView()
+        layoutMenuStackView()
+        setUpMenu()
+    }
+
+    private func layoutTableView() {
+        view.addSubview(tableView)
+        tableView.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            tableView.topAnchor.constraint(equalTo: view.topAnchor),
+            tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+            tableView.leftAnchor.constraint(equalTo: view.leftAnchor),
+            tableView.rightAnchor.constraint(equalTo: view.rightAnchor)
+            ])
+    }
+
+    private func layoutMenuStackView() {
+        view.addSubview(buttonStackView)
+        buttonStackView.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            buttonStackView.topAnchor.constraint(equalTo: view.topAnchor, constant: 22.0),
+            buttonStackView.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -22.0),
+            ])
+    }
+
+    private func setUpMenu() {
+        for menu in Menu.allCases {
+            switch menu {
+            case .reorder:
+                buttonStackView.addArrangedSubview(reorderButton)
+            case .turnOffTracking:
+                buttonStackView.addArrangedSubview(trackingSwitchWrapper)
+            }
+        }
+    }
+
+    // MARK: - Menu
+    @objc
+    private func reorderItems() {
+        if reorderButton.titleLabel?.text == Menu.reorder.rawValue {
+            tableView.isEditing = true
+            reorderButton.setTitle("Cancel", for: .normal)
+        } else {
+            tableView.isEditing = false
+            reorderButton.setTitle(Menu.reorder.rawValue, for: .normal)
+        }
+    }
+
+    @objc
+    private func turnTrackingOn(_ sender: UISwitch) {
+        guard let fpc = self.parent as? FloatingPanelController else { return }
+        if sender.isOn {
+            fpc.track(scrollView: tableView)
+        } else {
+            fpc.untrack(scrollView: tableView)
+        }
+    }
+
+    // MARK: - Actions
+
+    private func execute(command: Command) {
+        command.execute(for: self)
+    }
+
+    @objc
+    private func animateScroll() {
+        tableView.scrollToRow(at: IndexPath(row: lround(Double(items.count) / 2.0),
+                                            section: 0),
+                              at: .top, animated: true)
+    }
+
+    @objc
+    private func changeContentSize() {
+        let actionSheet = UIAlertController(title: "Change content size", message: "", preferredStyle: .actionSheet)
+        actionSheet.addAction(UIAlertAction(title: "Large", style: .default, handler: { (_) in
+            self.itemHeight = 66.0
+            self.changeItems(100)
+        }))
+        actionSheet.addAction(UIAlertAction(title: "Match", style: .default, handler: { (_) in
+            switch self.tableView.bounds.height {
+            case 585: // iPhone 6,7,8
+                self.itemHeight = self.tableView.bounds.height / 13.0
+                self.changeItems(13)
+            case 656: // iPhone {6,7,8} Plus
+                self.itemHeight = self.tableView.bounds.height / 16.0
+                self.changeItems(16)
+            default: // iPhone X family
+                self.itemHeight = self.tableView.bounds.height / 12.0
+                self.changeItems(12)
+            }
+        }))
+        actionSheet.addAction(UIAlertAction(title: "Short", style: .default, handler: { (_) in
+            self.itemHeight = 66.0
+            self.changeItems(3)
+        }))
+
+        self.present(actionSheet, animated: true, completion: nil)
+    }
+
+    private func changeItems(_ count: Int) {
+        items = Command.replace(items: (0..<count).map{ "\($0). No action" })
+        tableView.reloadData()
+    }
+
+    @objc
+    private func moveToFull() {
+        (self.parent as! FloatingPanelController).move(to: .full, animated: true)
+    }
+
+    @objc
+    private func moveToHalf() {
+        (self.parent as! FloatingPanelController).move(to: .half, animated: true)
+    }
+
+    @objc
+    private func close(sender: UIButton) {
+        //  Remove FloatingPanel from a view
+        (self.parent as! FloatingPanelController).removePanelFromParent(animated: true, completion: nil)
+    }
+}
+
+extension DebugTableViewController: UITableViewDataSource {
+    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
+        return items.count
+    }
+
+    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
+        return itemHeight
+    }
+
+    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
+        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
+        cell.textLabel?.text = items[indexPath.row]
+        return cell
+    }
+}
+
+extension DebugTableViewController: UITableViewDelegate {
+    func scrollViewDidScroll(_ scrollView: UIScrollView) {
+        print("TableView --- ", scrollView.contentOffset, scrollView.contentInset)
+    }
+
+    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
+        print("DebugTableViewController -- select row \(indexPath.row)")
+        guard let action = Command(rawValue: indexPath.row) else { return }
+        execute(command: action)
+    }
+
+    func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
+        return [
+            UITableViewRowAction(style: .destructive, title: "Delete", handler: { (action, path) in
+                self.items.remove(at: path.row)
+                tableView.deleteRows(at: [path], with: .automatic)
+            }),
+        ]
+    }
+
+    func tableView(_ tableView: UITableView, canMoveRowAt indexPath: IndexPath) -> Bool {
+        return true
+    }
+
+    func tableView(_ tableView: UITableView, moveRowAt sourceIndexPath: IndexPath, to destinationIndexPath: IndexPath) {
+        items.insert(items.remove(at: sourceIndexPath.row), at: destinationIndexPath.row)
+    }
+}

Examples/Samples/Sources/ViewControllers/DebugTextViewController.swift

@@ -0,0 +1,44 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+
+final class DebugTextViewController: UIViewController, UITextViewDelegate {
+    @IBOutlet weak var textView: UITextView!
+    @IBOutlet weak var textViewTopConstraint: NSLayoutConstraint!
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        textView.delegate = self
+        print("viewDidLoad: TextView --- ", textView.contentOffset, textView.contentInset)
+
+        if #available(iOS 11.0, *) {
+            textView.contentInsetAdjustmentBehavior = .never
+        }
+    }
+
+    override func viewWillLayoutSubviews() {
+        print("viewWillLayoutSubviews: TextView --- ", textView.contentOffset, textView.contentInset, textView.frame)
+    }
+
+    override func viewDidLayoutSubviews() {
+        super.viewDidLayoutSubviews()
+        print("viewDidLayoutSubviews: TextView --- ", textView.contentOffset, textView.contentInset, textView.frame)
+    }
+
+    override func viewDidAppear(_ animated: Bool) {
+        super.viewDidAppear(animated)
+        print("TextView --- ", textView.contentOffset, textView.contentInset, textView.frame)
+    }
+
+    func scrollViewDidScroll(_ scrollView: UIScrollView) {
+        print("TextView --- ", scrollView.contentOffset, scrollView.contentInset)
+        if #available(iOS 11.0, *) {
+            print("TextView --- ", scrollView.adjustedContentInset)
+        }
+    }
+
+    @IBAction func close(sender: UIButton) {
+        // (self.parent as? FloatingPanelController)?.removePanelFromParent(animated: true, completion: nil)
+        dismiss(animated: true, completion: nil)
+    }
+}

Examples/Samples/Sources/ViewControllers/DetailViewController.swift

@@ -0,0 +1,39 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+final class DetailViewController: InspectableViewController {
+    @IBOutlet weak var modeChangeView: UIStackView!
+    @IBOutlet weak var intrinsicHeightConstraint: NSLayoutConstraint!
+    @IBOutlet weak var closeButton: UIButton!
+    @IBAction func close(sender: UIButton) {
+        // (self.parent as? FloatingPanelController)?.removePanelFromParent(animated: true, completion: nil)
+        dismiss(animated: true, completion: nil)
+    }
+
+    @IBAction func buttonPressed(_ sender: UIButton) {
+        switch sender.titleLabel?.text {
+        case "Show":
+            performSegue(withIdentifier: "ShowSegue", sender: self)
+        case "Present Modally":
+            performSegue(withIdentifier: "PresentModallySegue", sender: self)
+        default:
+            break
+        }
+    }
+    @IBAction func modeChanged(_ sender: Any) {
+        guard let fpc = parent as? FloatingPanelController else { return }
+        fpc.contentMode = (fpc.contentMode == .static) ? .fitToBounds : .static
+    }
+
+    @IBAction func tapped(_ sender: Any) {
+        print("Detail panel is tapped!")
+    }
+    @IBAction func swipped(_ sender: Any) {
+        print("Detail panel is swipped!")
+    }
+    @IBAction func longPressed(_ sender: Any) {
+        print("Detail panel is longPressed!")
+    }
+}

Examples/Samples/Sources/ViewControllers/ImageViewController.swift

@@ -0,0 +1,69 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+final 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/Samples/Sources/ViewControllers/InspectorViewController.swift

@@ -0,0 +1,48 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+
+class InspectableViewController: UIViewController {
+    override func viewWillLayoutSubviews() {
+        super.viewWillLayoutSubviews()
+        print(">>> Content View: viewWillLayoutSubviews", layoutInsets)
+    }
+
+    override func viewDidLayoutSubviews() {
+        super.viewDidLayoutSubviews()
+        print(">>> Content View: viewDidLayoutSubviews", layoutInsets)
+    }
+
+    override func viewWillAppear(_ animated: Bool) {
+        super.viewWillAppear(animated)
+        print(">>> Content View: viewWillAppear", layoutInsets)
+    }
+
+    override func viewDidAppear(_ animated: Bool) {
+        super.viewDidAppear(animated)
+        print(">>> Content View: viewDidAppear", view.bounds, layoutInsets)
+    }
+
+    override func viewWillDisappear(_ animated: Bool) {
+        super.viewWillDisappear(animated)
+        print(">>> Content View: viewWillDisappear")
+    }
+
+    override func viewDidDisappear(_ animated: Bool) {
+        super.viewDidDisappear(animated)
+        print(">>> Content View: viewDidDisappear")
+    }
+
+    override func willMove(toParent parent: UIViewController?) {
+        super.willMove(toParent: parent)
+        print(">>> Content View: willMove(toParent: \(String(describing: parent))")
+    }
+
+    override func didMove(toParent parent: UIViewController?) {
+        super.didMove(toParent: parent)
+        print(">>> Content View: didMove(toParent: \(String(describing: parent))")
+    }
+    public override func willTransition(to newCollection: UITraitCollection, with coordinator: UIViewControllerTransitionCoordinator) {
+        print(">>> Content View: willTransition(to: \(newCollection), with: \(coordinator))", layoutInsets)
+    }
+}

Examples/Samples/Sources/ViewControllers/ModalViewController.swift

@@ -0,0 +1,79 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+final class ModalViewController: UIViewController, FloatingPanelControllerDelegate {
+    var fpc: FloatingPanelController!
+    var consoleVC: DebugTextViewController!
+
+    @IBOutlet weak var safeAreaView: UIView!
+
+    var isNewlayout: Bool = false
+
+    override func viewDidLoad() {
+        // Initialize FloatingPanelController
+        fpc = FloatingPanelController()
+        fpc.delegate = self
+
+        let appearance = SurfaceAppearance()
+        appearance.cornerRadius = 6.0
+        fpc.surfaceView.appearance = appearance
+
+        // Set a content view controller and track the scroll view
+        let consoleVC = storyboard?.instantiateViewController(withIdentifier: "ConsoleViewController") as! DebugTextViewController
+        fpc.set(contentViewController: consoleVC)
+        fpc.track(scrollView: consoleVC.textView)
+
+        self.consoleVC = consoleVC
+
+        //  Add FloatingPanel to self.view
+        fpc.addPanel(toParent: self, at: view.subviews.firstIndex(of: safeAreaView) ?? -1)
+    }
+
+    override func viewDidDisappear(_ animated: Bool) {
+        super.viewDidDisappear(animated)
+        //  Remove FloatingPanel from a view
+        fpc.removePanelFromParent(animated: false)
+    }
+
+    @IBAction func close(sender: UIButton) {
+        dismiss(animated: true, completion: nil)
+    }
+
+    @IBAction func moveToFull(sender: UIButton) {
+        fpc.move(to: .full, animated: true)
+    }
+    @IBAction func moveToHalf(sender: UIButton) {
+        fpc.move(to: .half, animated: true)
+    }
+    @IBAction func moveToTip(sender: UIButton) {
+        fpc.move(to: .tip, animated: true)
+    }
+    @IBAction func moveToHidden(sender: UIButton) {
+        fpc.move(to: .hidden, animated: true)
+    }
+    @IBAction func updateLayout(_ sender: Any) {
+        isNewlayout = !isNewlayout
+        UIView.animate(withDuration: 0.5) {
+            self.fpc.layout = (self.isNewlayout) ? ModalSecondLayout() : FloatingPanelBottomLayout()
+            self.fpc.invalidateLayout()
+        }
+    }
+
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+        return (isNewlayout) ? ModalSecondLayout() : FloatingPanelBottomLayout()
+    }
+
+    class ModalSecondLayout: 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(absoluteInset: 262, edge: .top, referenceGuide: .safeArea),
+                .tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .bottom, referenceGuide: .safeArea)
+            ]
+        }
+    }
+}

Examples/Samples/Sources/ViewControllers/MultiPanelController.swift

@@ -0,0 +1,67 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+import WebKit
+
+final class MultiPanelController: FloatingPanelController, FloatingPanelControllerDelegate {
+
+    private final class FirstPanelContentViewController: UIViewController {
+
+        lazy var webView: WKWebView = WKWebView()
+
+        override func viewDidLoad() {
+            super.viewDidLoad()
+            view.addSubview(webView)
+            webView.frame = view.bounds
+            webView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
+            webView.load(URLRequest(url: URL(string: "https://www.apple.com")!))
+
+            let vc = MultiSecondPanelController()
+            vc.setUpContent()
+            vc.addPanel(toParent: self)
+        }
+    }
+
+    private final class MultiSecondPanelController: FloatingPanelController {
+
+        private final class SecondPanelContentViewController: DebugTableViewController {}
+
+        func setUpContent() {
+            contentInsetAdjustmentBehavior = .never
+            let vc = SecondPanelContentViewController()
+            vc.loadViewIfNeeded()
+            vc.title = "Second Panel"
+            vc.buttonStackView.isHidden = true
+            let navigationController = UINavigationController(rootViewController: vc)
+            navigationController.navigationBar.barTintColor = .white
+            navigationController.navigationBar.titleTextAttributes = [
+                .foregroundColor: UIColor.black
+            ]
+            set(contentViewController: navigationController)
+            self.track(scrollView: vc.tableView)
+            surfaceView.containerMargins = .init(top: 24.0, left: 0.0, bottom: layoutInsets.bottom, right: 0.0)
+        }
+    }
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        layout = FirstViewLayout()
+        isRemovalInteractionEnabled = true
+
+        let vc = FirstPanelContentViewController()
+        set(contentViewController: vc)
+        track(scrollView: vc.webView.scrollView)
+    }
+
+    private final class FirstViewLayout: FloatingPanelLayout {
+        let position: FloatingPanelPosition = .bottom
+        let initialState: FloatingPanelState = .full
+        var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+            return [
+                .full: FloatingPanelLayoutAnchor(absoluteInset: 40.0, edge: .top, referenceGuide: .superview)
+            ]
+        }
+    }
+}
+

Examples/Samples/Sources/ViewControllers/NestedScrollViewController.swift

@@ -0,0 +1,18 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+
+final class NestedScrollViewController: UIViewController {
+    @IBOutlet weak var scrollView: UIScrollView!
+    @IBOutlet weak var nestedScrollView: UIScrollView!
+
+    @IBAction func longPressed(_ sender: Any) {
+        print("LongPressed!")
+    }
+    @IBAction func swipped(_ sender: Any) {
+        print("Swipped!")
+    }
+    @IBAction func tapped(_ sender: Any) {
+        print("Tapped!")
+    }
+}

Examples/Samples/Sources/ViewControllers/SettingsViewController.swift

@@ -0,0 +1,36 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+final class SettingsViewController: InspectableViewController {
+    @IBOutlet weak var largeTitlesSwicth: UISwitch!
+    @IBOutlet weak var translucentSwicth: UISwitch!
+    @IBOutlet weak var versionLabel: UILabel!
+
+    override func viewDidLoad() {
+        versionLabel.text = "Version: \(Bundle.main.infoDictionary?["CFBundleVersion"] ?? "--")"
+    }
+
+    override func viewDidLayoutSubviews() {
+        super.viewDidLayoutSubviews()
+        if #available(iOS 11.0, *) {
+            let prefersLargeTitles = navigationController!.navigationBar.prefersLargeTitles
+            largeTitlesSwicth.setOn(prefersLargeTitles, animated: false)
+        } else {
+            largeTitlesSwicth.isEnabled = false
+        }
+        let isTranslucent = navigationController!.navigationBar.isTranslucent
+        translucentSwicth.setOn(isTranslucent, animated: false)
+    }
+
+    @IBAction func toggleLargeTitle(_ sender: UISwitch) {
+        if #available(iOS 11.0, *) {
+            navigationController?.navigationBar.prefersLargeTitles = sender.isOn
+        }
+    }
+    @IBAction func toggleTranslucent(_ sender: UISwitch) {
+        navigationController?.navigationBar.isTranslucent = sender.isOn
+    }
+}
+

Examples/Samples/Sources/ViewControllers/TabBarViewController.swift

@@ -0,0 +1,248 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+final class TabBarViewController: UITabBarController {}
+
+final class TabBarContentViewController: UIViewController {
+    enum Tab3Mode {
+        case changeOffset
+        case changeAutoLayout
+        var label: String {
+            switch self {
+            case .changeAutoLayout: return "Use AutoLayout(OK)"
+            case .changeOffset: return "Use ContentOffset(NG)"
+            }
+        }
+    }
+    lazy var fpc = FloatingPanelController()
+    var consoleVC: DebugTextViewController!
+
+    var threeLayout: ThreeTabBarPanelLayout!
+    var tab3Mode: Tab3Mode = .changeAutoLayout
+    var switcherLabel: UILabel!
+
+    override func viewDidLoad() {
+        fpc.delegate = self
+
+        let appearance = SurfaceAppearance()
+        appearance.cornerRadius = 6.0
+        fpc.surfaceView.appearance = appearance
+
+        // Set a content view controller and track the scroll view
+        let consoleVC = storyboard?.instantiateViewController(withIdentifier: "ConsoleViewController") as! DebugTextViewController
+        fpc.set(contentViewController: consoleVC)
+        consoleVC.textView.delegate = self // MUST call it before fpc.track(scrollView:)
+        fpc.track(scrollView: consoleVC.textView)
+        self.consoleVC = consoleVC
+
+        //  Add FloatingPanel to self.view
+        fpc.addPanel(toParent: self)
+
+
+        switch tabBarItem.tag {
+        case 1:
+            fpc.behavior = TwoTabBarPanelBehavior()
+        case 2:
+            let switcher = UISwitch()
+            fpc.view.addSubview(switcher)
+            switcher.translatesAutoresizingMaskIntoConstraints = false
+            NSLayoutConstraint.activate([
+                switcher.bottomAnchor.constraint(equalTo: fpc.surfaceView.topAnchor, constant: -16.0),
+                switcher.rightAnchor.constraint(equalTo: fpc.surfaceView.rightAnchor, constant: -16.0),
+                ])
+            switcher.isOn = true
+            switcher.tintColor = .white
+            switcher.backgroundColor = .white
+            switcher.layer.cornerRadius = 16.0
+            switcher.addTarget(self,
+                               action: #selector(changeTab3Mode(_:)),
+                               for: .valueChanged)
+            let label = UILabel()
+            label.text = tab3Mode.label
+            fpc.view.addSubview(label)
+            switcherLabel = label
+            label.translatesAutoresizingMaskIntoConstraints = false
+            NSLayoutConstraint.activate([
+                label.centerYAnchor.constraint(equalTo: switcher.centerYAnchor, constant: 0.0),
+                label.rightAnchor.constraint(equalTo: switcher.leftAnchor, constant: -16.0),
+                ])
+
+            // Turn off the mask instead of content inset change
+            consoleVC.textView.clipsToBounds = false
+        default:
+            break
+        }
+    }
+
+    override func viewDidAppear(_ animated: Bool) {
+        super.viewDidAppear(animated)
+        fpc.invalidateLayout()
+    }
+
+    // MARK: - Action
+
+    @IBAction func close(sender: UIButton) {
+        dismiss(animated: true, completion: nil)
+    }
+
+    // MARK: - Private
+
+    @objc
+    private func changeTab3Mode(_ sender: UISwitch) {
+        if sender.isOn {
+            tab3Mode = .changeAutoLayout
+        } else {
+            tab3Mode = .changeOffset
+        }
+        switcherLabel.text = tab3Mode.label
+    }
+}
+
+extension TabBarContentViewController: UITextViewDelegate {
+    func scrollViewDidScroll(_ scrollView: UIScrollView) {
+        guard self.tabBarItem.tag == 2 else { return }
+        // Reset an invalid content offset by a user after updating the layout
+        // of `consoleVC.textView`.
+        // NOTE: FloatingPanel doesn't implicitly reset the offset(i.e.
+        // Using KVO of `scrollView.contentOffset`). Because it can lead to an
+        // infinite loop if a user also resets a content offset as below and,
+        // in the situation, a user has to modify the library.
+        if fpc.state != .full, fpc.surfaceLocation.y > fpc.surfaceLocation(for: .full).y {
+            scrollView.contentOffset = .zero
+        }
+    }
+}
+
+extension TabBarContentViewController: FloatingPanelControllerDelegate {
+    // MARK: - FloatingPanel
+
+    func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
+        switch self.tabBarItem.tag {
+        case 0:
+            return OneTabBarPanelLayout()
+        case 1:
+            return TwoTabBarPanelLayout()
+        case 2:
+            threeLayout = ThreeTabBarPanelLayout(parent: self)
+            return threeLayout
+        default:
+            return FloatingPanelBottomLayout()
+        }
+    }
+
+    func floatingPanelDidMove(_ vc: FloatingPanelController) {
+        guard self.tabBarItem.tag == 2 else { return }
+        switch tab3Mode {
+        case .changeAutoLayout:
+            /* Good solution: Manipulate top constraint */
+            assert(consoleVC.textViewTopConstraint != nil)
+            let safeAreaTop = vc.layoutInsets.top
+            if vc.surfaceLocation.y + threeLayout.topPadding < safeAreaTop {
+                consoleVC.textViewTopConstraint?.constant = min(safeAreaTop - vc.surfaceLocation.y,
+                                                                safeAreaTop)
+            } else {
+                consoleVC.textViewTopConstraint?.constant = threeLayout.topPadding
+            }
+        case .changeOffset:
+            /*
+             Bad solution: Manipulate scroll content inset
+
+             FloatingPanelController keeps a content offset in moving a panel
+             so that changing content inset or offset causes a buggy behavior.
+             */
+            guard let scrollView = consoleVC.textView else { return }
+            var insets = vc.adjustedContentInsets
+            if vc.surfaceView.frame.minY < vc.layoutInsets.top {
+                insets.top = vc.layoutInsets.top - vc.surfaceView.frame.minY
+            } else {
+                insets.top = 0.0
+            }
+            scrollView.contentInset = insets
+
+            if vc.surfaceView.frame.minY > 0 {
+                scrollView.contentOffset = CGPoint(x: 0.0,
+                                                   y: 0.0 - scrollView.contentInset.top)
+            }
+        }
+
+        if vc.surfaceLocation.y > vc.surfaceLocation(for: .half).y {
+            let progress = (vc.surfaceLocation.y - vc.surfaceLocation(for: .half).y)
+                / (vc.surfaceLocation(for: .tip).y - vc.surfaceLocation(for: .half).y)
+            threeLayout.leftConstraint.constant = max(min(progress, 1.0), 0.0) * threeLayout.sideMargin
+            threeLayout.rightConstraint.constant = -max(min(progress, 1.0), 0.0) * threeLayout.sideMargin
+        } else {
+            threeLayout.leftConstraint.constant = 0.0
+            threeLayout.rightConstraint.constant = 0.0
+        }
+    }
+}
+
+class OneTabBarPanelLayout: FloatingPanelLayout {
+    var initialState: FloatingPanelState { .tip }
+    var position: FloatingPanelPosition { .bottom }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 22.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
+    }
+}
+
+class TwoTabBarPanelLayout: FloatingPanelLayout {
+    var initialState: FloatingPanelState { .half }
+    var position: FloatingPanelPosition { .bottom }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 100.0, edge: .top, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 261.0, edge: .bottom, referenceGuide: .safeArea)
+        ]
+    }
+}
+
+class TwoTabBarPanelBehavior: FloatingPanelBehavior {
+    func allowsRubberBanding(for edges: UIRectEdge) -> Bool {
+        return [UIRectEdge.top, UIRectEdge.bottom].contains(edges)
+    }
+}
+
+
+class ThreeTabBarPanelLayout: FloatingPanelLayout {
+    weak var parentVC: UIViewController!
+
+    var leftConstraint: NSLayoutConstraint!
+    var rightConstraint: NSLayoutConstraint!
+
+    let topPadding: CGFloat = 17.0
+    let sideMargin: CGFloat = 16.0
+
+    init(parent: UIViewController) {
+        parentVC = parent
+    }
+
+    var initialState: FloatingPanelState { .half }
+    var position: FloatingPanelPosition { .bottom }
+    var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .top, referenceGuide: .superview),
+            .half: FloatingPanelLayoutAnchor(absoluteInset: 261.0 + parentVC.layoutInsets.bottom, edge: .bottom, referenceGuide: .superview),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 88.0 + parentVC.layoutInsets.bottom, edge: .bottom, referenceGuide: .superview),
+        ]
+    }
+
+    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)
+            rightConstraint = surfaceView.rightAnchor.constraint(equalTo: view.safeAreaLayoutGuide.rightAnchor, constant: 0.0)
+        } else {
+            leftConstraint = surfaceView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 0.0)
+            rightConstraint = surfaceView.rightAnchor.constraint(equalTo: view.rightAnchor, constant: 0.0)
+        }
+        return [ leftConstraint, rightConstraint ]
+    }
+}

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

@@ -3,6 +3,22 @@
 #import "ViewController.h"
 @import FloatingPanel;
 
+// Defining a custom FloatingPanelState
+@interface FloatingPanelState(Extended)
++ (FloatingPanelState *)LastQuart;
+@end
+
+@implementation FloatingPanelState(Extended)
+static FloatingPanelState *_lastQuart;
++ (FloatingPanelState *)LastQuart {
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        _lastQuart = [[FloatingPanelState alloc] initWithRawValue:@"lastquart" order:750];
+    });
+    return _lastQuart;
+}
+@end
+
 @interface ViewController()<FloatingPanelControllerDelegate>
 @end
 
@@ -20,7 +36,7 @@
     [fpc setBehavior:[MyFloatingPanelBehavior new]];
     [fpc setRemovalInteractionEnabled:NO];
 
-    [fpc addPanelToParent:self at:self.view.subviews.count  animated:NO];
+    [fpc addPanelToParent:self at:self.view.subviews.count animated:NO completion:nil];
     [fpc moveToState:FloatingPanelState.Tip animated:true completion:nil];
 
     [self updateAppearance: fpc];
@@ -59,12 +75,15 @@
 }
 - (NSDictionary<FloatingPanelState *, id<FloatingPanelLayoutAnchoring>> *)anchors {
     return @{
+        FloatingPanelState.LastQuart: [[FloatingPanelLayoutAnchor alloc] initWithFractionalInset:0.25
+                                                                                       edge:FloatingPanelReferenceEdgeTop
+                                                                             referenceGuide:FloatingPanelLayoutReferenceGuideSafeArea],
         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"
+  s.version             = "2.4.1"
   s.summary             = "FloatingPanel is a clean and easy-to-use UI component of a floating panel interface."
   s.description         = <<-DESC
 FloatingPanel is a clean and easy-to-use UI component for a new interface introduced in Apple Maps, Shortcuts and Stocks app.

FloatingPanel.xcodeproj/project.pbxproj

@@ -9,12 +9,11 @@
 /* Begin PBXBuildFile section */
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 		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 */; };
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-		545DB9DE215118C800CA77B8 /* UIExtensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DB9DD215118C800CA77B8 /* UIExtensions.swift */; };
 		545DB9E021511AC100CA77B8 /* Controller.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DB9DF21511AC100CA77B8 /* Controller.swift */; };
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 		546055BF2333C4740069F400 /* TestSupports.swift in Sources */ = {isa = PBXBuildFile; fileRef = 542753C722C49A8F00D17955 /* TestSupports.swift */; };
@@ -24,7 +23,7 @@
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 		5469F4B224B30F1100537F8A /* Position.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5469F4B124B30F1100537F8A /* Position.swift */; };
 		5469F4B424B30F3500537F8A /* LayoutReferences.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5469F4B324B30F3500537F8A /* LayoutReferences.swift */; };
-		549C371F2361E15E007D8058 /* UtilTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 549C371E2361E15D007D8058 /* UtilTests.swift */; };
+		549C371F2361E15E007D8058 /* ExtensionTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 549C371E2361E15D007D8058 /* ExtensionTests.swift */; };
 		549E944522CF295D0050AECF /* StateTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 549E944422CF295D0050AECF /* StateTests.swift */; };
 		54A6B6B122968B530077F348 /* CoreTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54A6B6B022968B530077F348 /* CoreTests.swift */; };
 		54A6B6B82296A8520077F348 /* SurfaceViewTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54A6B6B72296A8520077F348 /* SurfaceViewTests.swift */; };
@@ -33,6 +32,7 @@
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 		54CFBFC5215CD09C006B5735 /* Core.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CFBFC4215CD09C006B5735 /* Core.swift */; };
+		54DBA3DC262E938500D75969 /* Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54DBA3DB262E938500D75969 /* Extensions.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -56,7 +56,7 @@
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 		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>"; };
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 		545DB9C42151169500CA77B8 /* FloatingPanel.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = FloatingPanel.h; sourceTree = "<group>"; };
@@ -64,7 +64,6 @@
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 		545DB9D12151169500CA77B8 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
-		545DB9DD215118C800CA77B8 /* UIExtensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UIExtensions.swift; sourceTree = "<group>"; };
 		545DB9DF21511AC100CA77B8 /* Controller.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Controller.swift; sourceTree = "<group>"; };
 		545DBA2A2152383100CA77B8 /* GrabberView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GrabberView.swift; sourceTree = "<group>"; };
 		5469F49F24B003EF00537F8A /* LaunchScreen.storyboard */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = file.storyboard; path = LaunchScreen.storyboard; sourceTree = "<group>"; };
@@ -74,7 +73,7 @@
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 		5469F4B124B30F1100537F8A /* Position.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Position.swift; sourceTree = "<group>"; };
 		5469F4B324B30F3500537F8A /* LayoutReferences.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LayoutReferences.swift; sourceTree = "<group>"; };
-		549C371E2361E15D007D8058 /* UtilTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UtilTests.swift; sourceTree = "<group>"; };
+		549C371E2361E15D007D8058 /* ExtensionTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ExtensionTests.swift; sourceTree = "<group>"; };
 		549E944422CF295D0050AECF /* StateTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StateTests.swift; sourceTree = "<group>"; };
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 		54A6B6B72296A8520077F348 /* SurfaceViewTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SurfaceViewTests.swift; sourceTree = "<group>"; };
@@ -83,6 +82,7 @@
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 		54CFBFC4215CD09C006B5735 /* Core.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Core.swift; sourceTree = "<group>"; };
+		54DBA3DB262E938500D75969 /* Extensions.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Extensions.swift; sourceTree = "<group>"; };
 		54E740CA218AFD67005C1A34 /* FloatingPanelTesting.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = FloatingPanelTesting.app; sourceTree = BUILT_PRODUCTS_DIR; };
 /* End PBXFileReference section */
 
@@ -142,12 +142,12 @@
 				5469F4B324B30F3500537F8A /* LayoutReferences.swift */,
 				5469F4AF24B30E1500537F8A /* LayoutAnchoring.swift */,
 				5450EEE321646DF500135936 /* Behavior.swift */,
-				54352E9721A521CA00CBCA08 /* PassThroughView.swift */,
+				54352E9721A521CA00CBCA08 /* PassthroughView.swift */,
 				54CDC5D2215B6D5A007D205C /* SurfaceView.swift */,
 				54CDC5D4215B6D8D007D205C /* BackdropView.swift */,
 				545DBA2A2152383100CA77B8 /* GrabberView.swift */,
 				54352E9521A51A2500CBCA08 /* Transitioning.swift */,
-				545DB9DD215118C800CA77B8 /* UIExtensions.swift */,
+				54DBA3DB262E938500D75969 /* Extensions.swift */,
 				54ABD7AE216CCFF7002E6C13 /* Logger.swift */,
 				545DB9C42151169500CA77B8 /* FloatingPanel.h */,
 				545DB9C52151169500CA77B8 /* Info.plist */,
@@ -164,7 +164,7 @@
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 				54A6B6B72296A8520077F348 /* SurfaceViewTests.swift */,
 				549E944422CF295D0050AECF /* StateTests.swift */,
-				549C371E2361E15D007D8058 /* UtilTests.swift */,
+				549C371E2361E15D007D8058 /* ExtensionTests.swift */,
 				542753C722C49A8F00D17955 /* TestSupports.swift */,
 				545DB9D12151169500CA77B8 /* Info.plist */,
 			);
@@ -328,14 +328,14 @@
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 				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 */,
+				54DBA3DC262E938500D75969 /* Extensions.swift in Sources */,
 				5450EEE421646DF500135936 /* Behavior.swift in Sources */,
 				545DBA2B2152383100CA77B8 /* GrabberView.swift in Sources */,
 				54352E9621A51A2500CBCA08 /* Transitioning.swift in Sources */,
-				545DB9DE215118C800CA77B8 /* UIExtensions.swift in Sources */,
 				5469F4AE24B30D7E00537F8A /* State.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
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 			files = (
 				54A6B6B122968B530077F348 /* CoreTests.swift in Sources */,
-				549C371F2361E15E007D8058 /* UtilTests.swift in Sources */,
+				549C371F2361E15E007D8058 /* ExtensionTests.swift in Sources */,
 				545DB9D02151169500CA77B8 /* ControllerTests.swift in Sources */,
 				549E944522CF295D0050AECF /* StateTests.swift in Sources */,
 				542753C622C49A6E00D17955 /* LayoutTests.swift in Sources */,

README.md

@@ -35,6 +35,8 @@ The new interface displays the related contents and utilities in parallel as a u
         - [Support your landscape layout](#support-your-landscape-layout)
         - [Use the intrinsic size of a content in your panel layout](#use-the-intrinsic-size-of-a-content-in-your-panel-layout)
         - [Specify an anchor for each state by an inset of the `FloatingPanelController.view` frame](#specify-an-anchor-for-each-state-by-an-inset-of-the-floatingpanelcontrollerview-frame)
+        - [Change the backdrop alpha](#change-the-backdrop-alpha)
+        - [Using custome panel states](#using-custome-panel-states)
     - [Customize the behavior with `FloatingPanelBehavior` protocol](#customize-the-behavior-with-floatingpanelbehavior-protocol)
         - [Modify your floating panel's interaction](#modify-your-floating-panels-interaction)
         - [Activate the rubber-band effect on panel edges](#activate-the-rubber-band-effect-on-panel-edges)
@@ -53,6 +55,7 @@ The new interface displays the related contents and utilities in parallel as a u
     - [Create an additional floating panel for a detail](#create-an-additional-floating-panel-for-a-detail)
     - [Move a position with an animation](#move-a-position-with-an-animation)
     - [Work your contents together with a floating panel behavior](#work-your-contents-together-with-a-floating-panel-behavior)
+    - [Enabling the tap-to-dismiss action of the backdrop view](#enabling-the-tap-to-dismiss-action-of-the-backdrop-view)
 - [Notes](#notes)
     - ['Show' or 'Show Detail' Segues from `FloatingPanelController`'s content view controller](#show-or-show-detail-segues-from-floatingpanelcontrollers-content-view-controller)
     - [UISearchController issue](#uisearchcontroller-issue)
@@ -71,7 +74,7 @@ The new interface displays the related contents and utilities in parallel as a u
 - [x] Multi panel support
 - [x] Modal presentation
 - [x] 4 positioning support(top, left, bottom, right)
-- [x] 1~3 magnetic anchors(full, half, tip)
+- [x] 1 or more magnetic anchors(full, half, tip and more)
 - [x] Layout support for all trait environments(i.e. Landscape orientation)
 - [x] Common UI elements: surface, backdrop and grabber handle
 - [x] Free from common issues of Auto Layout and gesture handling
@@ -163,7 +166,7 @@ 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
 
@@ -370,6 +373,46 @@ class MyFullScreenLayout: FloatingPanelLayout {
 
 :pencil2: `FloatingPanelFullScreenLayout` is deprecated on v1.
 
+#### Change the backdrop alpha
+
+You can change the backdrop alpha by `FloatingPanelLayout.backdropAlpha(for:)` for each state(`.full`, `.half` and `.tip`).
+
+For instance, if a panel seems like the backdrop view isn't there on `.half` state, it's time to implement the backdropAlpha API and return a value for the state as below.
+
+```swift
+class MyPanelLayout: FloatingPanelLayout {
+    func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+        switch state {
+        case .full, .half: return 0.3
+        default: return 0.0
+        }
+    }
+}
+```
+
+#### Using custome panel states
+
+You're able to define custom panel states and use them as the following example.
+
+```swift
+extension FloatingPanelState {
+    static let lastQuart: FloatingPanelState = FloatingPanelState(rawValue: "lastQuart", order: 750)
+    static let firstQuart: FloatingPanelState = FloatingPanelState(rawValue: "firstQuart", order: 250)
+}
+
+class FloatingPanelLayoutWithCustomState: FloatingPanelBottomLayout {
+    override var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
+        return [
+            .full: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .top, referenceGuide: .safeArea),
+            .lastQuart: FloatingPanelLayoutAnchor(fractionalInset: 0.75, edge: .bottom, referenceGuide: .safeArea),
+            .half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
+            .firstQuart: FloatingPanelLayoutAnchor(fractionalInset: 0.25, edge: .bottom, referenceGuide: .safeArea),
+            .tip: FloatingPanelLayoutAnchor(absoluteInset: 20.0, edge: .bottom, referenceGuide: .safeArea),
+        ]
+    }
+}
+```
+
 ### Customize the behavior with `FloatingPanelBehavior` protocol
 
 #### Modify your floating panel's interaction
@@ -522,8 +565,8 @@ override func viewDidLoad() {
     surfaceTapGesture.isEnabled = (fpc.position == .tip)
 }
 
-// Enable `surfaceTapGesture` only at `tip` position
-func floatingPanelDidChangePosition(_ vc: FloatingPanelController) {
+// Enable `surfaceTapGesture` only at `tip` state
+func floatingPanelDidChangeState(_ vc: FloatingPanelController) {
     surfaceTapGesture.isEnabled = (vc.position == .tip)
 }
 ```
@@ -616,6 +659,14 @@ class ViewController: UIViewController, FloatingPanelControllerDelegate {
 }
 ```
 
+### Enabling the tap-to-dismiss action of the backdrop view
+
+The tap-to-dismiss action is disabled by default. So it needs to be enabled as below.
+
+```swift
+fpc.backdropView.dismissalTapGestureRecognizer.isEnabled = true
+```
+
 ## Notes
 
 ### 'Show' or 'Show Detail' Segues from `FloatingPanelController`'s content view controller

Sources/BackdropView.swift

@@ -7,5 +7,5 @@ import UIKit
 public class BackdropView: UIView {
 
     /// The gesture recognizer for tap gestures to dismiss a panel.
-    public var dismissalTapGestureRecognizer: UITapGestureRecognizer!
+    @objc public var dismissalTapGestureRecognizer: UITapGestureRecognizer!
 }

Sources/Behavior.swift

@@ -43,44 +43,41 @@ public protocol FloatingPanelBehavior {
     /// 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
+    
+    /// Returns the velocity threshold for the default interactive removal gesture.
+    ///
+    /// In case `floatingPanel:shouldRemoveAt:with` is implemented, this value will not be used. The default value of `FloatingPanelDefaultBehavior` is 5.5
+    @objc optional
+    var removalInteractionVelocityThreshold: CGFloat { get }
 }
 
 /// The default behavior object for a panel
 ///
 /// This behavior object is fine-tuned to behave as a search panel(card) in Apple Maps on iPhone portrait orientation.
-public class FloatingPanelDefaultBehavior: FloatingPanelBehavior {
-    public var springDecelerationRate: CGFloat {
+open class FloatingPanelDefaultBehavior: FloatingPanelBehavior {
+    public init() {}
+
+    open var springDecelerationRate: CGFloat {
         return UIScrollView.DecelerationRate.fast.rawValue + 0.001
     }
 
-    public var springResponseTime: CGFloat {
+    open var springResponseTime: CGFloat {
         return 0.4
     }
 
-    public var momentumProjectionRate: CGFloat {
+    open var momentumProjectionRate: CGFloat {
         return UIScrollView.DecelerationRate.normal.rawValue
     }
 
-    public 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))
-    }
-
-    public func allowsRubberBanding(for edge: UIRectEdge) -> Bool {
+    open func allowsRubberBanding(for edge: UIRectEdge) -> Bool {
         return false
     }
+    
+    open var removalInteractionVelocityThreshold: CGFloat = 5.5
 }
 
 class BehaviorAdapter {
@@ -103,6 +100,10 @@ class BehaviorAdapter {
     var momentumProjectionRate: CGFloat {
         behavior.momentumProjectionRate ?? FloatingPanelDefaultBehavior().momentumProjectionRate
     }
+    
+    var removalInteractionVelocityThreshold: CGFloat {
+        behavior.removalInteractionVelocityThreshold ?? FloatingPanelDefaultBehavior().removalInteractionVelocityThreshold
+    }
 
     func redirectionalProgress(from: FloatingPanelState, to: FloatingPanelState) -> CGFloat {
         behavior.redirectionalProgress?(vc, from: from, to: to) ?? FloatingPanelDefaultBehavior().redirectionalProgress(vc,from: from, to: to)

Sources/Controller.swift

@@ -5,7 +5,7 @@ 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 {
+@objc public protocol FloatingPanelControllerDelegate {
     /// 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
@@ -26,10 +26,12 @@ import UIKit
     @objc(floatingPanel:animatorForDismissingWithVelocity:) optional
     func floatingPanel(_ fpc: FloatingPanelController, animatorForDismissingWith velocity: CGVector) -> UIViewPropertyAnimator
 
-    /// Called when a panel has changed to a new position. Can be called inside an animation block, so any
-    /// view properties set inside this function will be automatically animated alongside a panel.
+    /// Called when a panel has changed to a new state.
+    ///
+    /// This can be called inside an animation block for presenting, dismissing a panel or moving a panel with your
+    /// animation. So any view properties set inside this function will be automatically animated alongside a panel.
     @objc optional
-    func floatingPanelDidChangePosition(_ fpc: FloatingPanelController)
+    func floatingPanelDidChangeState(_ fpc: FloatingPanelController)
 
     /// Asks the delegate if dragging should begin by the pan gesture recognizer.
     @objc optional
@@ -274,7 +276,7 @@ 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
@@ -396,20 +398,8 @@ open class FloatingPanelController: UIViewController {
     }
 
     private func activateLayout(forceLayout: Bool = false) {
-        floatingPanel.layoutAdapter.prepareLayout()
-
-        // preserve the current content offset if contentInsetAdjustmentBehavior is `.always`
-        var contentOffset: CGPoint?
-        if contentInsetAdjustmentBehavior == .always {
-            contentOffset = trackingScrollView?.contentOffset
-        }
-
-        floatingPanel.layoutAdapter.updateStaticConstraint()
-        floatingPanel.layoutAdapter.activateLayout(for: floatingPanel.state, forceLayout: forceLayout)
-
-        if let contentOffset = contentOffset {
-            trackingScrollView?.contentOffset = contentOffset
-        }
+        floatingPanel.activateLayout(forceLayout: forceLayout,
+                                     contentInsetAdjustmentBehavior: contentInsetAdjustmentBehavior)
     }
 
     func remove() {
@@ -427,6 +417,9 @@ open class FloatingPanelController: UIViewController {
     // MARK: - Container view controller interface
 
     /// Shows the surface view at the initial position defined by the current layout
+    /// - Parameters:
+    ///     - animated: Pass true to animate the presentation; otherwise, pass false.
+    ///     - completion: The block to execute after the presentation finishes. This block has no return value and takes no parameters. You may specify nil for this parameter.
     @objc(show:completion:)
     public func show(animated: Bool = false, completion: (() -> Void)? = nil) {
         // Must apply the current layout here
@@ -468,8 +461,9 @@ open class FloatingPanelController: UIViewController {
     ///     - parent: A parent view controller object that displays FloatingPanelController's view. A container view controller object isn't applicable.
     ///     - viewIndex: Insert the surface view managed by the controller below the specified view index. By default, the surface view will be added to the end of the parent list of subviews.
     ///     - animated: Pass true to animate the presentation; otherwise, pass false.
-    @objc(addPanelToParent:at:animated:)
-    public func addPanel(toParent parent: UIViewController, at viewIndex: Int = -1, animated: Bool = false) {
+    ///     - completion: The block to execute after the presentation finishes. This block has no return value and takes no parameters. You may specify nil for this parameter.
+    @objc(addPanelToParent:at:animated:completion:)
+    public func addPanel(toParent parent: UIViewController, at viewIndex: Int = -1, animated: Bool = false, completion: (() -> Void)? = nil) {
         guard self.parent == nil else {
             log.warning("Already added to a parent(\(parent))")
             return
@@ -498,8 +492,9 @@ open class FloatingPanelController: UIViewController {
             ])
 
         show(animated: animated) { [weak self] in
-            guard let `self` = self else { return }
+            guard let self = self else { return }
             self.didMove(toParent: parent)
+            completion?()
         }
     }
 
@@ -517,7 +512,7 @@ open class FloatingPanelController: UIViewController {
         delegate?.floatingPanelWillRemove?(self)
 
         hide(animated: animated) { [weak self] in
-            guard let `self` = self else { return }
+            guard let self = self else { return }
 
             self.willMove(toParent: nil)
 
@@ -531,13 +526,13 @@ open class FloatingPanelController: UIViewController {
     }
 
     /// Moves the position to the specified position.
+    ///
     /// - Parameters:
     ///     - to: Pass a FloatingPanelPosition value to move the surface view to the position.
     ///     - animated: Pass true to animate the presentation; otherwise, pass false.
     ///     - completion: The block to execute after the view controller has finished moving. This block has no return value and takes no parameters. You may specify nil for this parameter.
     @objc(moveToState:animated:completion:)
     public func move(to: FloatingPanelState, animated: Bool, completion: (() -> Void)? = nil) {
-        assert(floatingPanel.layoutAdapter.vc != nil, "Use show(animated:completion)")
         floatingPanel.move(to: to, animated: animated, completion: completion)
     }
 
@@ -598,6 +593,14 @@ 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
@@ -641,10 +644,31 @@ 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 {
-    private static let dismissSwizzling: Any? = {
+    private static let dismissSwizzling: Void = {
         let aClass: AnyClass! = UIViewController.self //object_getClass(vc)
         if let imp = class_getMethodImplementation(aClass, #selector(dismiss(animated:completion:))),
             let originalAltMethod = class_getInstanceMethod(aClass, #selector(fp_original_dismiss(animated:completion:))) {
@@ -653,10 +677,8 @@ extension FloatingPanelController {
         let originalMethod = class_getInstanceMethod(aClass, #selector(dismiss(animated:completion:)))
         let swizzledMethod = class_getInstanceMethod(aClass, #selector(fp_dismiss(animated:completion:)))
         if let originalMethod = originalMethod, let swizzledMethod = swizzledMethod {
-            // switch implementation..
             method_exchangeImplementations(originalMethod, swizzledMethod)
         }
-        return nil
     }()
 }
 

Sources/Core.swift

@@ -24,7 +24,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         didSet {
             log.debug("state changed: \(oldValue) -> \(state)")
             if let vc = ownerVC {
-                vc.delegate?.floatingPanelDidChangePosition?(vc)
+                vc.delegate?.floatingPanelDidChangeState?(vc)
             }
         }
     }
@@ -32,7 +32,8 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     let panGestureRecognizer: FloatingPanelPanGestureRecognizer
     var isRemovalInteractionEnabled: Bool = false
 
-    fileprivate var animator: UIViewPropertyAnimator?
+    fileprivate var isSuspended: Bool = false // Prevent a memory leak in the modal transition
+    fileprivate var transitionAnimator: UIViewPropertyAnimator?
     fileprivate var moveAnimator: NumericSpringAnimator?
 
     private var initialSurfaceLocation: CGPoint = .zero
@@ -68,11 +69,8 @@ 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()
 
@@ -94,6 +92,11 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         backdropView.addGestureRecognizer(tapGesture)
     }
 
+    deinit {
+        // Release `NumericSpringAnimator.displayLink` from the run loop.
+        self.moveAnimator?.stopAnimation(false)
+    }
+
     func move(to: FloatingPanelState, animated: Bool, completion: (() -> Void)? = nil) {
         move(from: state, to: to, animated: animated, completion: completion)
     }
@@ -104,7 +107,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             completion?()
             return
         }
-        if state != layoutAdapter.edgeMostState {
+        if state != layoutAdapter.mostExpandedState {
             lockScrollView()
         }
         tearDownActiveInteraction()
@@ -112,8 +115,9 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         interruptAnimationIfNeeded()
 
         if animated {
-            func updateScrollView() {
-                if self.state == self.layoutAdapter.edgeMostState, abs(self.layoutAdapter.offsetFromEdgeMost) <= 1.0 {
+            let updateScrollView: () -> Void = { [weak self] in
+                guard let self = self else { return }
+                if self.state == self.layoutAdapter.mostExpandedState, abs(self.layoutAdapter.offsetFromMostExpandedAnchor) <= 1.0 {
                     self.unlockScrollView()
                 } else {
                     self.lockScrollView()
@@ -123,14 +127,15 @@ 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)
-            case (let from, .hidden):
+                animator = vc.animatorForPresenting(to: to)
+            case (_, .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) {
+                move(to: to, with: 0) { [weak self] in
+                    guard let self = self else { return }
+
+                    self.moveAnimator = nil
                     updateScrollView()
                     completion?()
                 }
@@ -142,7 +147,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                 && layoutAdapter.isIntrinsicAnchor(state: to)
 
             animator.addAnimations { [weak self] in
-                guard let `self` = self else { return }
+                guard let self = self else { return }
 
                 self.state = to
                 self.updateLayout(to: to)
@@ -153,18 +158,22 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                 }
             }
             animator.addCompletion { [weak self] _ in
-                guard let `self` = self else { return }
-                self.animator = nil
+                guard let self = self else { return }
+
+                self.transitionAnimator = nil
                 updateScrollView()
                 self.ownerVC?.notifyDidMove()
                 completion?()
             }
-            self.animator = animator
+            self.transitionAnimator = animator
+            if isSuspended {
+                return
+            }
             animator.startAnimation()
         } else {
             self.state = to
             self.updateLayout(to: to)
-            if self.state == self.layoutAdapter.edgeMostState {
+            if self.state == self.layoutAdapter.mostExpandedState {
                 self.unlockScrollView()
             } else {
                 self.lockScrollView()
@@ -177,8 +186,37 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
     // MARK: - Layout update
 
+    func activateLayout(forceLayout: Bool = false,
+                        contentInsetAdjustmentBehavior: FloatingPanelController.ContentInsetAdjustmentBehavior) {
+        layoutAdapter.prepareLayout()
+
+        // preserve the current content offset if contentInsetAdjustmentBehavior is `.always`
+        var contentOffset: CGPoint?
+        if contentInsetAdjustmentBehavior == .always {
+            contentOffset = scrollView?.contentOffset
+        }
+
+        layoutAdapter.updateStaticConstraint()
+        layoutAdapter.activateLayout(for: state, forceLayout: true)
+
+        // Update the backdrop alpha only when called in `Controller.show(animated:completion:)`
+        // Because that prevents a backdrop flicking just before presenting a panel(#466).
+        if forceLayout {
+            backdropView.alpha = getBackdropAlpha(for: state)
+        }
+
+        if let contentOffset = contentOffset {
+            scrollView?.contentOffset = contentOffset
+        }
+    }
+
     private func updateLayout(to target: FloatingPanelState) {
-        self.layoutAdapter.activateLayout(for: state, forceLayout: true)
+        self.layoutAdapter.activateLayout(for: target, forceLayout: true)
+        self.backdropView.alpha = self.getBackdropAlpha(for: target)
+    }
+
+    private func getBackdropAlpha(for target: FloatingPanelState) -> CGFloat {
+        return target == .hidden ? 0.0 : layoutAdapter.backdropAlpha(for: target)
     }
 
     func getBackdropAlpha(at cur: CGFloat, with translation: CGFloat) -> CGFloat {
@@ -187,8 +225,8 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
         let segment = layoutAdapter.segment(at: cur, forward: forwardY)
 
-        let lowerState = segment.lower ?? layoutAdapter.edgeMostState
-        let upperState = segment.upper ?? layoutAdapter.edgeLeastState
+        let lowerState = segment.lower ?? layoutAdapter.mostExpandedState
+        let upperState = segment.upper ?? layoutAdapter.leastExpandedState
 
         let preState = forwardY ? lowerState : upperState
         let nextState = forwardY ? upperState : lowerState
@@ -201,9 +239,8 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
         if pre == next {
             return preAlpha
-        } else {
-            return preAlpha + max(min(1.0, 1.0 - (next - cur) / (next - pre) ), 0.0) * (nextAlpha - preAlpha)
         }
+        return preAlpha + max(min(1.0, 1.0 - (next - cur) / (next - pre) ), 0.0) * (nextAlpha - preAlpha)
     }
 
     // MARK: - UIGestureRecognizerDelegate
@@ -340,7 +377,7 @@ 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.fp_displayScale)
+            let belowEdgeMost = 0 > layoutAdapter.offsetFromMostExpandedAnchor + (1.0 / surfaceView.fp_displayScale)
 
             log.debug("""
                 scroll gesture(\(state):\(panGesture.state)) -- \
@@ -354,7 +391,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
             if belowEdgeMost {
                 // Scroll offset pinning
-                if state == layoutAdapter.edgeMostState {
+                if state == layoutAdapter.mostExpandedState {
                     if interactionInProgress {
                         log.debug("settle offset --", value(of: initialScrollOffset))
                         stopScrolling(at: initialScrollOffset)
@@ -372,7 +409,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                 if interactionInProgress {
                     lockScrollView()
                 } else {
-                    if state == layoutAdapter.edgeMostState, self.animator == nil {
+                    if state == layoutAdapter.mostExpandedState, self.transitionAnimator == nil {
                         switch layoutAdapter.position {
                         case .top, .left:
                             if offsetDiff < 0 && velocity > 0 {
@@ -400,14 +437,14 @@ class Core: NSObject, UIGestureRecognizerDelegate {
                             return
                         }
                     }
-                    if state == layoutAdapter.edgeMostState {
+                    if state == layoutAdapter.mostExpandedState {
                         // Adjust a small gap of the scroll offset just after swiping down starts in the grabber area.
                         if grabberAreaFrame.contains(location), grabberAreaFrame.contains(initialLocation) {
                             stopScrolling(at: initialScrollOffset)
                         }
                     }
                 } else {
-                    if state == layoutAdapter.edgeMostState {
+                    if state == layoutAdapter.mostExpandedState {
                         switch layoutAdapter.position {
                         case .top, .left:
                             if velocity < 0, !allowScrollPanGesture(for: scrollView) {
@@ -492,16 +529,16 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             animator.stopAnimation(true)
             endAttraction(false)
         }
-        if let animator = self.animator {
-            guard 0 >= layoutAdapter.offsetFromEdgeMost else { return }
+        if let animator = self.transitionAnimator {
+            guard 0 >= layoutAdapter.offsetFromMostExpandedAnchor else { return }
             log.debug("a panel animation(interruptible: \(animator.isInterruptible)) interrupted!!!")
             if animator.isInterruptible {
                 animator.stopAnimation(false)
                 // A user can stop a panel at the nearest Y of a target position so this fine-tunes
                 // the a small gap between the presentation layer frame and model layer frame
                 // to unlock scroll view properly at finishAnimation(at:)
-                if abs(layoutAdapter.offsetFromEdgeMost) <= 1.0 {
-                    layoutAdapter.surfaceLocation = layoutAdapter.surfaceLocation(for: layoutAdapter.edgeMostState)
+                if abs(layoutAdapter.offsetFromMostExpandedAnchor) <= 1.0 {
+                    layoutAdapter.surfaceLocation = layoutAdapter.surfaceLocation(for: layoutAdapter.mostExpandedState)
                 }
                 animator.finishAnimation(at: .current)
             } else {
@@ -527,22 +564,27 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         }
 
         guard
-            state == layoutAdapter.edgeMostState,  // When not top most(i.e. .full), don't scroll.
+            state == layoutAdapter.mostExpandedState,  // When not top most(i.e. .full), don't scroll.
             interactionInProgress == false,        // When interaction already in progress, don't scroll.
-            0 == layoutAdapter.offsetFromEdgeMost
+            0 == layoutAdapter.offsetFromMostExpandedAnchor
         else {
             return false
         }
 
-        // When the current and initial point within grabber area, do scroll.
+        // When the current point is within grabber area but the initial point is not, do scroll.
         if grabberAreaFrame.contains(point), !grabberAreaFrame.contains(initialLocation) {
             return true
         }
 
+        // When the initial point is within grabber area and the current point is out of surface, don't scroll.
+        if grabberAreaFrame.contains(initialLocation), !surfaceView.frame.contains(point) {
+            return false
+        }
+
         let scrollViewFrame = scrollView.convert(scrollView.bounds, to: surfaceView)
         guard
-            scrollViewFrame.contains(initialLocation), // When initialLocation not in scrollView, don't scroll.
-            !grabberAreaFrame.contains(point)           // When point within grabber area, don't scroll.
+            scrollViewFrame.contains(initialLocation), // When the initial point not in scrollView, don't scroll.
+            !grabberAreaFrame.contains(point)          // When point within grabber area, don't scroll.
         else {
             return false
         }
@@ -570,6 +612,9 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         if scrollView.isDecelerating {
             return true
         }
+        if let tableView = (scrollView as? UITableView), tableView.isEditing {
+            return true
+        }
 
         return false
     }
@@ -581,7 +626,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         log.debug("panningBegan -- location = \(value(of: location))")
 
         guard let scrollView = scrollView else { return }
-        if state == layoutAdapter.edgeMostState {
+        if state == layoutAdapter.mostExpandedState {
             if grabberAreaFrame.contains(location) {
                 initialScrollOffset = scrollView.contentOffset
             }
@@ -648,10 +693,11 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             return
         }
 
-        stopScrollDeceleration = (0 > layoutAdapter.offsetFromEdgeMost + (1.0 / surfaceView.fp_displayScale)) // Projecting the dragging to the scroll dragging or not
+        stopScrollDeceleration = (0 > layoutAdapter.offsetFromMostExpandedAnchor + (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 }
+                guard let self = self else { return }
+
                 self.stopScrolling(at: self.initialScrollOffset)
             }
         }
@@ -697,14 +743,14 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
         // Workaround: Disable a tracking scroll to prevent bouncing a scroll content in a panel animating
         let isScrollEnabled = scrollView?.isScrollEnabled
-        if let scrollView = scrollView, targetPosition != .full {
+        if let scrollView = scrollView, targetPosition != layoutAdapter.mostExpandedState {
             scrollView.isScrollEnabled = false
         }
 
         startAttraction(to: targetPosition, with: velocity)
 
         // Workaround: Reset `self.scrollView.isScrollEnabled`
-        if let scrollView = scrollView, targetPosition != .full,
+        if let scrollView = scrollView, targetPosition != layoutAdapter.mostExpandedState,
             let isScrollEnabled = isScrollEnabled {
             scrollView.isScrollEnabled = isScrollEnabled
         }
@@ -717,15 +763,16 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         if let result = vc.delegate?.floatingPanel?(vc, shouldRemoveAt: vc.surfaceLocation, with: velocityVector) {
             return result
         }
+        let threshold = behaviorAdapter.removalInteractionVelocityThreshold
         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)
         }
     }
 
@@ -737,7 +784,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         var offset: CGPoint = .zero
 
         initialSurfaceLocation = layoutAdapter.surfaceLocation
-        if state == layoutAdapter.edgeMostState, let scrollView = scrollView {
+        if state == layoutAdapter.mostExpandedState, let scrollView = scrollView {
             if grabberAreaFrame.contains(location) {
                 initialScrollOffset = scrollView.contentOffset
             } else {
@@ -782,7 +829,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         interactionInProgress = false
 
         // Prevent to keep a scroll view indicator visible at the half/tip position
-        if targetPosition != layoutAdapter.edgeMostState {
+        if targetPosition != layoutAdapter.mostExpandedState {
             lockScrollView()
         }
 
@@ -790,6 +837,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 
     private func tearDownActiveInteraction() {
+        guard panGestureRecognizer.isEnabled else { return }
         // Cancel the pan gesture so that panningEnd(with:velocity:) is called
         panGestureRecognizer.isEnabled = false
         panGestureRecognizer.isEnabled = true
@@ -823,16 +871,19 @@ class Core: NSObject, UIGestureRecognizerDelegate {
             decelerationRate: behaviorAdapter.springDecelerationRate,
             responseTime: behaviorAdapter.springResponseTime,
             update: { [weak self] data in
-                guard let self = self else { return }
+                guard let self = self,
+                      let ownerVC = self.ownerVC // Ensure the owner vc is existing for `layoutAdapter.surfaceLocation`
+                else { return }
                 animationConstraint.constant = data.value
                 let current = self.value(of: self.layoutAdapter.surfaceLocation)
                 let translation = data.value - initialData.value
                 self.backdropView.alpha = self.getBackdropAlpha(at: current, with: translation)
-                self.ownerVC?.notifyDidMove()
+                ownerVC.notifyDidMove()
         },
             completion: { [weak self] in
-                guard let self = self else { return }
-                self.layoutAdapter.activateLayout(for: targetPosition, forceLayout: true)
+                guard let self = self,
+                      self.ownerVC != nil else { return }
+                self.updateLayout(to: targetPosition)
                 completion()
         })
         moveAnimator?.startAnimation()
@@ -856,9 +907,9 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         log.debug("""
             finishAnimation -- state = \(state) \
             surface location = \(layoutAdapter.surfaceLocation) \
-            edge most position = \(layoutAdapter.surfaceLocation(for: layoutAdapter.edgeMostState))
+            edge most position = \(layoutAdapter.surfaceLocation(for: layoutAdapter.mostExpandedState))
             """)
-        if finished, state == layoutAdapter.edgeMostState, abs(layoutAdapter.offsetFromEdgeMost) <= 1.0 {
+        if finished, state == layoutAdapter.mostExpandedState, abs(layoutAdapter.offsetFromMostExpandedAnchor) <= 1.0 {
             unlockScrollView()
         }
     }
@@ -885,7 +936,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     func targetPosition(from currentY: CGFloat, with velocity: CGFloat) -> (FloatingPanelState) {
         log.debug("targetPosition -- currentY = \(currentY), velocity = \(velocity)")
 
-        let sortedPositions = layoutAdapter.sortedDirectionalStates
+        let sortedPositions = layoutAdapter.sortedAnchorStatesByCoordinate
 
         guard sortedPositions.count > 1 else {
             return state
@@ -893,7 +944,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
 
         // Projection
         let decelerationRate = behaviorAdapter.momentumProjectionRate
-        let baseY = abs(layoutAdapter.position(for: layoutAdapter.edgeLeastState) - layoutAdapter.position(for: layoutAdapter.edgeMostState))
+        let baseY = abs(layoutAdapter.position(for: layoutAdapter.leastExpandedState) - layoutAdapter.position(for: layoutAdapter.mostExpandedState))
         let vecY = velocity / baseY
         var pY = project(initialVelocity: vecY, decelerationRate: decelerationRate) * baseY + currentY
 
@@ -989,7 +1040,7 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 
     private func allowScrollPanGesture(for scrollView: UIScrollView) -> Bool {
-        guard state == layoutAdapter.edgeMostState else { return false }
+        guard state == layoutAdapter.mostExpandedState else { return false }
         var offsetY: CGFloat = 0
         switch layoutAdapter.position {
         case .top, .left:
@@ -1021,7 +1072,7 @@ public final class FloatingPanelPanGestureRecognizer: UIPanGestureRecognizer {
     public override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
         super.touchesBegan(touches, with: event)
         initialLocation = touches.first?.location(in: view) ?? .zero
-        if floatingPanel?.animator != nil || floatingPanel?.moveAnimator != nil {
+        if floatingPanel?.transitionAnimator != nil || floatingPanel?.moveAnimator != nil {
             self.state = .began
         }
     }
@@ -1182,3 +1233,12 @@ private class NumericSpringAnimator: NSObject {
         v = (v + h * o2 * (xt - x)) / det
     }
 }
+
+extension FloatingPanelController {
+    func suspendTransitionAnimator(_ suspended: Bool) {
+        self.floatingPanel.isSuspended = suspended
+    }
+    var transitionAnimator: UIViewPropertyAnimator? {
+        return self.floatingPanel.transitionAnimator
+    }
+}

Sources/Extensions.swift

@@ -2,16 +2,38 @@
 
 import UIKit
 
-internal func displayTrunc(_ v: CGFloat, by s: CGFloat) -> CGFloat {
-    let base = (1 / s)
-    let t = v.rounded(.down)
-    return t + ((v - t) / base).rounded(.toNearestOrAwayFromZero) * base
+// MARK: - CoreGraphics
+
+extension CGFloat {
+    /// Returns this value rounded to an logical pixel value by a display scale
+    func rounded(by displayScale: CGFloat) -> CGFloat {
+        return (self * displayScale).rounded(.toNearestOrAwayFromZero) / displayScale
+    }
+    func isEqual(to: CGFloat, on displayScale: CGFloat) -> Bool {
+        return self.rounded(by: displayScale) == to.rounded(by: displayScale)
+    }
 }
 
-internal func displayEqual(_ lhs: CGFloat, _ rhs: CGFloat, by displayScale: CGFloat) -> Bool {
-    return displayTrunc(lhs, by: displayScale) == displayTrunc(rhs, by: displayScale)
+extension CGPoint {
+    static var leastNonzeroMagnitude: CGPoint {
+        return CGPoint(x: CGFloat.leastNonzeroMagnitude, y: CGFloat.leastNonzeroMagnitude)
+    }
+
+    static func + (lhs: CGPoint, rhs: CGPoint) -> CGPoint {
+        return CGPoint(x: lhs.x + rhs.x, y: lhs.y + rhs.y)
+    }
+
+    static func - (lhs: CGPoint, rhs: CGPoint) -> CGPoint {
+        return CGPoint(x: lhs.x - rhs.x, y: lhs.y - rhs.y)
+    }
+
+    static prefix func - (point: CGPoint) -> CGPoint {
+        return CGPoint(x: -point.x, y: -point.y)
+    }
 }
 
+// MARK: - UIKit
+
 protocol LayoutGuideProvider {
     var topAnchor: NSLayoutYAxisAnchor { get }
     var leftAnchor: NSLayoutXAxisAnchor { get }
@@ -164,24 +186,6 @@ extension UISpringTimingParameters {
     }
 }
 
-extension CGPoint {
-    static var leastNonzeroMagnitude: CGPoint {
-        return CGPoint(x: CGFloat.leastNonzeroMagnitude, y: CGFloat.leastNonzeroMagnitude)
-    }
-
-    static func + (lhs: CGPoint, rhs: CGPoint) -> CGPoint {
-        return CGPoint(x: lhs.x + rhs.x, y: lhs.y + rhs.y)
-    }
-
-    static func - (lhs: CGPoint, rhs: CGPoint) -> CGPoint {
-        return CGPoint(x: lhs.x - rhs.x, y: lhs.y - rhs.y)
-    }
-
-    static prefix func - (point: CGPoint) -> CGPoint {
-        return CGPoint(x: -point.x, y: -point.y)
-    }
-}
-
 extension NSLayoutConstraint {
     static func activate(constraint: NSLayoutConstraint?) {
         guard let constraint = constraint else { return }
@@ -201,3 +205,70 @@ extension UIEdgeInsets {
         return self.top + self.bottom
     }
 }
+
+extension UIBezierPath {
+    static func path(roundedRect rect: CGRect, appearance: SurfaceAppearance) -> UIBezierPath {
+        let cornerRadius = appearance.cornerRadius;
+        if #available(iOS 13.0, *) {
+            if appearance.cornerCurve == .circular {
+                let path = UIBezierPath()
+                let start = CGPoint(x: rect.minX + cornerRadius, y: rect.minY)
+
+                path.move(to: start)
+
+                path.addLine(to: CGPoint(x: rect.maxX - cornerRadius, y: rect.minY))
+                if cornerRadius > 0 {
+                    path .addArc(withCenter: CGPoint(x: rect.maxX - cornerRadius,
+                                                     y: rect.minY + cornerRadius),
+                                 radius: cornerRadius,
+                                 startAngle: -0.5 * .pi,
+                                 endAngle: 0,
+                                 clockwise: true)
+                }
+
+                path.addLine(to: CGPoint(x: rect.maxX, y: rect.maxY - cornerRadius))
+
+                if cornerRadius > 0 {
+                    path.addArc(withCenter: CGPoint(x: rect.maxX - cornerRadius,
+                                                    y: rect.maxY - cornerRadius),
+                                radius: cornerRadius,
+                                startAngle: 0,
+                                endAngle: .pi * 0.5,
+                                clockwise: true)
+                }
+
+                path.addLine(to: CGPoint(x: rect.minX + cornerRadius, y: rect.maxY))
+
+                if cornerRadius > 0 {
+                    path.addArc(withCenter: CGPoint(x: rect.minX + cornerRadius,
+                                                    y: rect.maxY - cornerRadius),
+                                radius: cornerRadius,
+                                startAngle: .pi * 0.5,
+                                endAngle: .pi,
+                                clockwise: true)
+                }
+
+                path.addLine(to: CGPoint(x: rect.minX, y: rect.minY + cornerRadius))
+
+                if cornerRadius > 0 {
+                    path.addArc(withCenter: CGPoint(x: rect.minX + cornerRadius,
+                                                    y: rect.minY + cornerRadius),
+                                radius: cornerRadius,
+                                startAngle: .pi,
+                                endAngle: .pi * 1.5,
+                                clockwise: true)
+                }
+
+                path.addLine(to: start)
+
+                path.close()
+
+                return path
+            }
+        }
+        return UIBezierPath(roundedRect: rect,
+                            byRoundingCorners: [.allCorners],
+                            cornerRadii: CGSize(width: cornerRadius,
+                                                height: cornerRadius))
+    }
+}

Sources/Info.plist

@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>2.0.0</string>
+	<string>2.4.1</string>
 	<key>CFBundleVersion</key>
 	<string>$(CURRENT_PROJECT_VERSION)</string>
 </dict>

Sources/Layout.swift

@@ -60,9 +60,7 @@ struct LayoutSegment {
 }
 
 class LayoutAdapter {
-    weak var vc: FloatingPanelController!
-    private weak var surfaceView: SurfaceView!
-    private weak var backdropView: BackdropView!
+    private unowned var vc: FloatingPanelController
     private let defaultLayout = FloatingPanelBottomLayout()
 
     fileprivate var layout: FloatingPanelLayout {
@@ -71,16 +69,21 @@ 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
+        return vc.fp_safeAreaInsets
     }
 
     private var initialConst: CGFloat = 0.0
 
     private var fixedConstraints: [NSLayoutConstraint] = []
-    private var fullConstraints: [NSLayoutConstraint] = []
-    private var halfConstraints: [NSLayoutConstraint] = []
-    private var tipConstraints: [NSLayoutConstraint] = []
+
+    private var stateConstraints: [FloatingPanelState: [NSLayoutConstraint]] = [:]
     private var offConstraints: [NSLayoutConstraint] = []
     private var fitToBoundsConstraint: NSLayoutConstraint?
 
@@ -89,10 +92,16 @@ class LayoutAdapter {
 
     private var staticConstraint: NSLayoutConstraint?
 
-    private var activeStates: Set<FloatingPanelState> {
+    private var anchorStates: Set<FloatingPanelState> {
         return Set(layout.anchors.keys)
     }
 
+    private var sortedAnchorStates: [FloatingPanelState] {
+        return anchorStates.sorted(by: {
+            return $0.order < $1.order
+        })
+    }
+
     var initialState: FloatingPanelState {
         layout.initialState
     }
@@ -101,18 +110,12 @@ class LayoutAdapter {
         layout.position
     }
 
-    var orderedStates: [FloatingPanelState] {
-        return activeStates.sorted(by: {
-            return $0.order < $1.order
-        })
-    }
-
     var validStates: Set<FloatingPanelState> {
-        return activeStates.union([.hidden])
+        return anchorStates.union([.hidden])
     }
 
-    var sortedDirectionalStates: [FloatingPanelState] {
-        return activeStates.sorted(by: {
+    var sortedAnchorStatesByCoordinate: [FloatingPanelState] {
+        return anchorStates.sorted(by: {
             switch position {
             case .top, .left:
                 return $0.order < $1.order
@@ -122,30 +125,26 @@ class LayoutAdapter {
         })
     }
 
-    private var directionalLeastState: FloatingPanelState {
-        return sortedDirectionalStates.first ?? .hidden
+    private var leastCoordinateState: FloatingPanelState {
+        return sortedAnchorStatesByCoordinate.first ?? .hidden
     }
 
-    private var directionalMostState: FloatingPanelState {
-        return sortedDirectionalStates.last ?? .hidden
+    private var mostCoordinateState: FloatingPanelState {
+        return sortedAnchorStatesByCoordinate.last ?? .hidden
     }
 
-    var edgeLeastState: FloatingPanelState {
-        if orderedStates.count == 1 {
+    var leastExpandedState: FloatingPanelState {
+        if sortedAnchorStates.count == 1 {
             return .hidden
         }
-        return orderedStates.first ?? .hidden
+        return sortedAnchorStates.first ?? .hidden
     }
 
-    var edgeMostState: FloatingPanelState {
-        if orderedStates.count == 1 {
-            return orderedStates[0]
+    var mostExpandedState: FloatingPanelState {
+        if sortedAnchorStates.count == 1 {
+            return sortedAnchorStates[0]
         }
-        return orderedStates.last ?? .hidden
-    }
-
-    var edgeMostY: CGFloat {
-        return position(for: edgeMostState)
+        return sortedAnchorStates.last ?? .hidden
     }
 
     var adjustedContentInsets: UIEdgeInsets {
@@ -220,7 +219,7 @@ class LayoutAdapter {
                     }
                 }
             } else {
-                pos = displayTrunc(edgePosition(surfaceView.frame), by: surfaceView.fp_displayScale)
+                pos = edgePosition(surfaceView.frame).rounded(by: surfaceView.fp_displayScale)
             }
             switch position {
             case .top, .bottom:
@@ -262,12 +261,12 @@ class LayoutAdapter {
         }
     }
 
-    var offsetFromEdgeMost: CGFloat {
+    var offsetFromMostExpandedAnchor: CGFloat {
         switch position {
         case .top, .left:
-            return edgePosition(surfaceView.presentationFrame) - position(for: directionalMostState)
+            return edgePosition(surfaceView.presentationFrame) - position(for: mostExpandedState)
         case .bottom, .right:
-            return position(for: directionalLeastState) - edgePosition(surfaceView.presentationFrame)
+            return position(for: mostExpandedState) - edgePosition(surfaceView.presentationFrame)
         }
     }
 
@@ -284,18 +283,13 @@ 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.fp_displayScale)
+        let pos = position(for: state).rounded(by: surfaceView.fp_displayScale)
         switch layout.position {
         case .top, .bottom:
             return CGPoint(x: 0.0, y: pos)
@@ -327,6 +321,22 @@ class LayoutAdapter {
                 }
                 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 - dimension + diff
+            }
         case let anchor as FloatingPanelLayoutAnchor:
             let referenceBounds = anchor.referenceGuide == .safeArea ? bounds.inset(by: safeAreaInsets) : bounds
             let diff = anchor.isAbsolute ? anchor.inset : position.mainDimension(referenceBounds.size) * anchor.inset
@@ -364,7 +374,8 @@ 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
@@ -436,25 +447,13 @@ class LayoutAdapter {
     }
 
     private func updateStateConstraints() {
-        NSLayoutConstraint.deactivate(fullConstraints + halfConstraints + tipConstraints + offConstraints)
-
-        if let fullAnchor = layout.anchors[.full] {
-            fullConstraints = fullAnchor.layoutConstraints(vc, for: position)
-            fullConstraints.forEach {
-                $0.identifier = "FloatingPanel-full-constraint"
-            }
-        }
-        if let halfAnchor = layout.anchors[.half] {
-            halfConstraints = halfAnchor.layoutConstraints(vc, for: position)
-            halfConstraints.forEach {
-                $0.identifier = "FloatingPanel-half-constraint"
-            }
-        }
-        if let tipAnchors = layout.anchors[.tip] {
-            tipConstraints = tipAnchors.layoutConstraints(vc, for: position)
-            tipConstraints.forEach {
-                $0.identifier = "FloatingPanel-tip-constraint"
-            }
+        let allStateConstraints = stateConstraints.flatMap { $1 }
+        NSLayoutConstraint.deactivate(allStateConstraints + offConstraints)
+        stateConstraints.removeAll()
+        for state in layout.anchors.keys {
+            stateConstraints[state] = layout.anchors[state]?
+                .layoutConstraints(vc, for: position)
+                .map{ $0.identifier = "FloatingPanel-\(state)-constraint"; return $0 }
         }
         let hiddenAnchor = layout.anchors[.hidden] ?? self.hiddenAnchor
         offConstraints = hiddenAnchor.layoutConstraints(vc, for: position)
@@ -471,7 +470,7 @@ class LayoutAdapter {
 
         tearDownAttraction()
 
-        NSLayoutConstraint.deactivate(fullConstraints + halfConstraints + tipConstraints + offConstraints)
+        NSLayoutConstraint.deactivate(stateConstraints.flatMap { $1 } + offConstraints)
 
         initialConst = edgePosition(surfaceView.frame) + offset.y
 
@@ -487,7 +486,7 @@ class LayoutAdapter {
             constraint = surfaceView.leftAnchor.constraint(equalTo: vc.view.leftAnchor, constant: initialConst)
         }
 
-        constraint.priority = .defaultHigh
+        constraint.priority = .required
         constraint.identifier = "FloatingPanel-interaction"
 
         NSLayoutConstraint.activate([constraint])
@@ -511,7 +510,7 @@ class LayoutAdapter {
 
         let anchor = layout.anchors[state] ?? self.hiddenAnchor
 
-        NSLayoutConstraint.deactivate(fullConstraints + halfConstraints + tipConstraints + offConstraints)
+        NSLayoutConstraint.deactivate(stateConstraints.flatMap { $1 } + offConstraints)
         NSLayoutConstraint.deactivate(constraint: interactionConstraint)
         interactionConstraint = nil
 
@@ -630,7 +629,6 @@ class LayoutAdapter {
     // The method is separated from prepareLayout(to:) for the rotation support
     // It must be called in FloatingPanelController.traitCollectionDidChange(_:)
     func updateStaticConstraint() {
-        guard let vc = vc else { return }
         NSLayoutConstraint.deactivate(constraint: staticConstraint)
         staticConstraint = nil
 
@@ -639,20 +637,32 @@ class LayoutAdapter {
             return
         }
 
-        let anchor = layout.anchors[self.edgeMostState]!
-        if anchor is FloatingPanelIntrinsicLayoutAnchor {
-            var constant = layout.position.mainDimension(surfaceView.intrinsicContentSize)
+        let anchor = layout.anchors[self.mostExpandedState]!
+        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.mostCoordinateState))
             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.leastCoordinateState))
             }
         }
 
@@ -673,8 +683,8 @@ class LayoutAdapter {
             log.debug("update surface location = \(surfaceLocation)")
         }
 
-        let minConst: CGFloat = position(for: directionalLeastState)
-        let maxConst: CGFloat = position(for: directionalMostState)
+        let minConst: CGFloat = position(for: leastCoordinateState)
+        let maxConst: CGFloat = position(for: mostCoordinateState)
 
         var const = initialConst + diff
 
@@ -730,8 +740,6 @@ class LayoutAdapter {
 
         var state = state
 
-        setBackdropAlpha(of: state)
-
         if validStates.contains(state) == false {
             state = layout.initialState
         }
@@ -741,17 +749,16 @@ class LayoutAdapter {
         // on-screen and off-screen view which includes
         // UIStackView(i.e. Settings view in Samples.app)
         updateStateConstraints()
+
         switch state {
-        case .full:
-            NSLayoutConstraint.activate(fullConstraints)
-        case .half:
-            NSLayoutConstraint.activate(halfConstraints)
-        case .tip:
-            NSLayoutConstraint.activate(tipConstraints)
         case .hidden:
             NSLayoutConstraint.activate(offConstraints)
         default:
-            break
+            if let constraints = stateConstraints[state] {
+                NSLayoutConstraint.activate(constraints)
+            } else {
+                log.error("Couldn't find any constraints for \(state)")
+            }
         }
     }
 
@@ -762,21 +769,13 @@ class LayoutAdapter {
         surfaceView.superview?.layoutIfNeeded()
     }
 
-    private func setBackdropAlpha(of target: FloatingPanelState) {
-        if target == .hidden {
-            self.backdropView.alpha = 0.0
-        } else {
-            self.backdropView.alpha = backdropAlpha(for: target)
-        }
-    }
-
     func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
         return layout.backdropAlpha?(for: state) ?? defaultLayout.backdropAlpha(for: state)
     }
 
     fileprivate func checkLayout() {
         // Verify layout configurations
-        assert(activeStates.count > 0)
+        assert(anchorStates.count > 0)
         assert(validStates.contains(layout.initialState),
                "Does not include an initial state (\(layout.initialState)) in (\(validStates))")
         /* This assertion does not work in a device rotating
@@ -796,7 +795,7 @@ extension LayoutAdapter {
         /// |-------|-------|===o===|  |-------|===o===|-------|
         /// pos: o/x, segment: =
 
-        let sortedStates = sortedDirectionalStates
+        let sortedStates = sortedAnchorStatesByCoordinate
 
         let upperIndex: Int?
         if forward {

Sources/LayoutAnchoring.swift

@@ -8,22 +8,25 @@ import UIKit
     func layoutConstraints(_ fpc: FloatingPanelController, for position: FloatingPanelPosition) -> [NSLayoutConstraint]
 }
 
-/// A layout anchor object that anchors a panel in a state.
+/// 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 */ {
-    /// Initializes and returns a layout anchor object to specify an absolute inset value for the position of a panel.
+
+    /// Returns a layout anchor with the specified inset by an absolute value, edge and reference guide for a panel.
     ///
-    /// The inset is a distance from the edge of the specified layout guide.
+    /// 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
     }
-    /// Initializes and returns a layout anchor object to specify a fractional inset value for the position of a panel.
+
+    /// Returns a layout anchor with the specified inset by a fractional value, edge and reference guide for a panel.
     ///
-    /// The inset is a distance from the edge of the specified layout guide. The value is a floating-point number
-    /// in the range 0.0 to 1.0, where 0.0 represents zero distance from the edge and 1.0 represents a distance
-    /// to the opposite edge.
+    /// 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
@@ -91,19 +94,20 @@ public extension FloatingPanelLayoutAnchor {
     }
 }
 
-
-/// A layout anchor object that anchors a panel in a state using the intrinsic size for a content.
+/// An object that defines how to settles a panel with the intrinsic size for a content.
 @objc final public class FloatingPanelIntrinsicLayoutAnchor: NSObject, FloatingPanelLayoutAnchoring /*, NSCopying */ {
-    /// Initializes and returns a layout anchor object to specify an absolute offset value for the position of a panel.
+
+    /// Returns a layout anchor with the specified offset by an absolute value and reference guide for a panel.
     ///
-    /// The offset is a distance from a position at which a panel displays the entire content.
+    /// 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
     }
 
-    /// Initializes and returns a layout anchor object to specify a fractional offset value for the position of a panel.
+    /// 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.
@@ -136,3 +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/Logger.swift

@@ -3,6 +3,7 @@
 import Foundation
 import os.log
 
+// Must be a variable to use `hook` property in testing
 var log = {
     return Logger()
 }()
@@ -68,7 +69,7 @@ struct Logger {
 
         hook?(log, level)
 
-        os_log("%@", log: osLog, type: level.osLogType, log)
+        os_log("%{public}@", log: osLog, type: level.osLogType, log)
     }
 
     private func getPrettyFunction(_ function: String, _ file: String) -> String {

Sources/PassthroughView.swift

@@ -2,8 +2,8 @@
 
 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/State.swift

@@ -4,7 +4,7 @@ import Foundation
 
 /// An object that represents the display state of a panel in a screen.
 @objc
-public class FloatingPanelState: NSObject, NSCopying, RawRepresentable {
+open class FloatingPanelState: NSObject, NSCopying, RawRepresentable {
     public typealias RawValue = String
 
     required public init?(rawValue: RawValue) {
@@ -13,6 +13,7 @@ public class FloatingPanelState: NSObject, NSCopying, RawRepresentable {
         super.init()
     }
 
+    @objc
     public init(rawValue: RawValue, order: Int) {
         self.rawValue = rawValue
         self.order = order
@@ -33,7 +34,7 @@ public class FloatingPanelState: NSObject, NSCopying, RawRepresentable {
     }
 
     public override var debugDescription: String {
-        return description
+        return "<FloatingPanel.FloatingPanelState: \(Unmanaged.passUnretained(self).toOpaque())>"
     }
 
     /// A panel state indicates the entire panel is shown.

Sources/SurfaceView.swift

@@ -50,6 +50,12 @@ public class SurfaceAppearance: NSObject {
     /// 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
 
+    /// Defines the curve used for rendering the rounded corners of the layer.
+    ///
+    /// Defaults to `.circular`.
+    @available(iOS 13.0, *)
+    public lazy var cornerCurve: CALayerCornerCurve = .circular
+
     /// An array of shadows used to create drop shadows underneath a surface view.
     public var shadows: [Shadow] = [Shadow()]
 
@@ -311,8 +317,8 @@ public class SurfaceView: UIView {
 
         containerView.backgroundColor = appearance.backgroundColor
 
-        updateShadow()
         updateCornerRadius()
+        updateShadow()
         updateBorder()
 
         grabberHandle.layer.cornerRadius = grabberHandleSize.height / 2
@@ -336,10 +342,9 @@ public class SurfaceView: UIView {
             shadowLayer.frame = layer.bounds
 
             let spread = shadow.spread
-            let shadowPath = UIBezierPath(roundedRect: containerView.frame.insetBy(dx: -spread,
-                                                                                   dy: -spread),
-                                          byRoundingCorners: [.allCorners],
-                                          cornerRadii: CGSize(width: appearance.cornerRadius, height: 0))
+            let shadowRect = containerView.frame.insetBy(dx: -spread, dy: -spread)
+            let shadowPath = UIBezierPath.path(roundedRect: shadowRect,
+                                               appearance: appearance)
             shadowLayer.shadowPath = shadowPath.cgPath
             shadowLayer.shadowColor = shadow.color.cgColor
             shadowLayer.shadowOffset = shadow.offset
@@ -348,16 +353,16 @@ public class SurfaceView: UIView {
             shadowLayer.shadowOpacity = shadow.opacity
 
             let mask = CAShapeLayer()
-            let path = UIBezierPath(roundedRect: containerView.frame,
-                                    byRoundingCorners: [.allCorners],
-                                    cornerRadii: CGSize(width: appearance.cornerRadius, height: 0))
+            let path = UIBezierPath.path(roundedRect: containerView.frame,
+                                         appearance: appearance)
             let size = window?.bounds.size ?? CGSize(width: 1000.0, height: 1000.0)
             path.append(UIBezierPath(rect: layer.bounds.insetBy(dx: -size.width,
                                                                 dy: -size.height)))
             mask.fillRule = .evenOdd
             mask.path = path.cgPath
             if #available(iOS 13.0, *) {
-                mask.cornerCurve = containerView.layer.cornerCurve
+                containerView.layer.cornerCurve = appearance.cornerCurve
+                mask.cornerCurve = appearance.cornerCurve
             }
             shadowLayer.mask = mask
         }

Sources/Transitioning.swift

@@ -61,7 +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) {
@@ -86,19 +86,29 @@ 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)
     }
 
-    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
+    func interruptibleAnimator(using transitionContext: UIViewControllerContextTransitioning) -> UIViewImplicitlyAnimating {
         guard
             let fpc = transitionContext.viewController(forKey: .to) as? FloatingPanelController
         else { fatalError() }
 
-        fpc.show(animated: true) {
+        if let animator = fpc.transitionAnimator {
+            return animator
+        }
+
+        fpc.suspendTransitionAnimator(true)
+        fpc.show(animated: true) { [weak fpc] in
+            fpc?.suspendTransitionAnimator(false)
             transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
         }
+        return fpc.transitionAnimator!
+    }
+
+    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
+        self.interruptibleAnimator(using: transitionContext).startAnimation()
     }
 }
 
@@ -108,19 +118,29 @@ 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)
     }
 
-    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
+    func interruptibleAnimator(using transitionContext: UIViewControllerContextTransitioning) -> UIViewImplicitlyAnimating {
         guard
             let fpc = transitionContext.viewController(forKey: .from) as? FloatingPanelController
         else { fatalError() }
 
-        fpc.hide(animated: true) {
+        if let animator = fpc.transitionAnimator {
+            return animator
+        }
+
+        fpc.suspendTransitionAnimator(true)
+        fpc.hide(animated: true) { [weak fpc] in
+            fpc?.suspendTransitionAnimator(false)
             transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
         }
+        return fpc.transitionAnimator!
+    }
+
+    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
+        self.interruptibleAnimator(using: transitionContext).startAnimation()
     }
 }
 

Tests/CoreTests.swift

@@ -185,6 +185,57 @@ class CoreTests: XCTestCase {
         XCTAssertEqual(fpc.floatingPanel.getBackdropAlpha(at: halfPos, with: -1 * distance2), 0.0)
     }
 
+
+    func test_updateBackdropAlpha() {
+        class BackdropTestLayout: FloatingPanelTestLayout {
+            override var initialState: FloatingPanelState { .hidden }
+            func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
+                switch state {
+                case .full: return 0.3
+                case .half: return 0.0
+                case .tip: return 0.3
+                default: return 0.0
+                }
+            }
+        }
+        let fpc = FloatingPanelController()
+        fpc.layout = BackdropTestLayout()
+
+        fpc.showForTest()
+
+        fpc.move(to: .full, animated: false)
+        XCTAssertEqual(floor(fpc.backdropView.alpha * 1000_000) / 1000_000, 0.3)
+
+        fpc.move(to: .half, animated: false)
+        XCTAssertEqual(fpc.backdropView.alpha, 0.0)
+
+        fpc.move(to: .tip, animated: false)
+        XCTAssertEqual(floor(fpc.backdropView.alpha * 1000_000) / 1000_000, 0.3)
+
+        let exp1 = expectation(description: "move to full with animation")
+        fpc.move(to: .full, animated: true) {
+            exp1.fulfill()
+        }
+        wait(for: [exp1], timeout: 1.0)
+        XCTAssertEqual(floor(fpc.backdropView.alpha * 1000_000) / 1000_000, 0.3)
+
+        let exp2 = expectation(description: "move to half with animation")
+        fpc.move(to: .half, animated: true) {
+            exp2.fulfill()
+        }
+        wait(for: [exp2], timeout: 1.0)
+        XCTAssertEqual(fpc.backdropView.alpha, 0.0)
+
+        let exp3 = expectation(description: "move to tip with animation")
+        fpc.move(to: .tip, animated: true) {
+            exp3.fulfill()
+        }
+        fpc.contentMode = .fitToBounds
+        XCTAssertEqual(fpc.backdropView.alpha, 0.0) // Must not affect the backdrop alpha by changing the content mode
+        wait(for: [exp3], timeout: 1.0)
+        XCTAssertEqual(floor(fpc.backdropView.alpha * 1000_000) / 1000_000, 0.3)
+    }
+
     func test_targetPosition_1positions() {
         class FloatingPanelLayout1Positions: FloatingPanelLayout {
             let initialState: FloatingPanelState = .full
@@ -715,6 +766,13 @@ class CoreTests: XCTestCase {
             (#line, tipPos, CGPoint(x: 0.0, y: 1000.0), .hidden),
             ])
     }
+
+    func test_keep_pan_gesture_disabled() {
+        let fpc = FloatingPanelController()
+        fpc.panGestureRecognizer.isEnabled = false
+        fpc.showForTest()
+        XCTAssertFalse(fpc.panGestureRecognizer.isEnabled)
+    }
 }
 
 private class FloatingPanelLayout3Positions: FloatingPanelTestLayout {

Tests/ExtensionTests.swift

@@ -0,0 +1,12 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import XCTest
+@testable import FloatingPanel
+
+class ExtensionTests: XCTestCase {
+    func test_roundedByDisplayScale() {
+        XCTAssertEqual(CGFloat(333.222).rounded(by: 3), 333.3333333333333)
+        XCTAssertNotEqual(CGFloat(333.5).rounded(by: 3), 333.66666666666674)
+        XCTAssertTrue(CGFloat(333.5).isEqual(to: 333.66666666666674, on: 3.0))
+    }
+}

Tests/LayoutTests.swift

@@ -13,8 +13,8 @@ class LayoutTests: XCTestCase {
     override func tearDown() {}
 
     func test_layoutAdapter_topAndBottomMostState() {
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeMostState, .full)
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeLeastState, .tip)
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.mostExpandedState, .full)
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.leastExpandedState, .tip)
 
         class FloatingPanelLayoutWithHidden: FloatingPanelLayout {
             var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring]  {
@@ -38,12 +38,12 @@ class LayoutTests: XCTestCase {
             let position: FloatingPanelPosition = .bottom
         }
         fpc.layout = FloatingPanelLayoutWithHidden()
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeMostState, .full)
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeLeastState, .hidden)
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.mostExpandedState, .full)
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.leastExpandedState, .hidden)
 
         fpc.layout = FloatingPanelLayout2Positions()
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeMostState, .half)
-        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.edgeLeastState, .tip)
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.mostExpandedState, .half)
+        XCTAssertEqual(fpc.floatingPanel.layoutAdapter.leastExpandedState, .tip)
     }
 
     func test_layoutSegment_3position() {

Tests/TestSupports.swift

@@ -18,7 +18,7 @@ extension FloatingPanelController {
 class FloatingPanelTestDelegate: FloatingPanelControllerDelegate {
     var position: FloatingPanelState = .hidden
     var didMoveCallback: ((FloatingPanelController) -> Void)?
-    func floatingPanelDidChangePosition(_ vc: FloatingPanelController) {
+    func floatingPanelDidChangeState(_ vc: FloatingPanelController) {
         position = vc.state
     }
     func floatingPanelDidMove(_ vc: FloatingPanelController) {

Tests/UtilTests.swift

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