Improve doc comments in LayoutAnchoring.swift

This PR modifies the transitionDuration(using:) method in FloatingPanelController to return 0.0 instead of calling fatalError when the FloatingPanelController instance is not found. This change is crucial for several reasons:

1. Avoiding Crashes in Production: Using fatalError in production can lead to unexpected crashes, which are detrimental to user experience. It's safer to return a default value like 0.0 and handle the scenario gracefully.

2. Improved Stability: By returning 0.0, the application can continue running, allowing for better stability and user satisfaction. This approach also aligns with the principle of fail-safety, where the system continues operating under error conditions.

3. Real-World Case: In our large-scale project, we encountered a crash at this specific point due to the fatalError. Given the size and complexity of our application, it has been challenging to pinpoint the exact cause. Switching to a return value of 0.0 would significantly help us mitigate the issue and maintain app stability while we investigate further.

4. Maintainability: Returning a default value makes the codebase more maintainable and easier to debug, as it avoids abrupt termination and allows for logging or other error handling mechanisms.

.circleci/config.yml

@@ -7,15 +7,8 @@ jobs:
     steps:
       - checkout
       - run: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=14.5,name=iPhone 12 Pro'
-  test-ios13_7-iPhone_11_Pro:
-    macos:
-      xcode: 12.5.1
-    steps:
-      - checkout
-      - run: xcodebuild clean test -scheme FloatingPanel -workspace FloatingPanel.xcworkspace -destination 'platform=iOS Simulator,OS=13.7,name=iPhone 11 Pro'
 
 workflows:
   test: 
     jobs:
       - test-ios14_5-iPhone_12_Pro
-      - test-ios13_7-iPhone_11_Pro

.github/workflows/ci.yml

@@ -18,6 +18,9 @@ jobs:
       fail-fast: false
       matrix:
         include:
+          - swift: "5.10"
+            xcode: "15.4"
+            runs-on: macos-14
           - swift: "5.9"
             xcode: "15.2"
             runs-on: macos-13
@@ -33,17 +36,8 @@ jobs:
           - swift: "5.5"
             xcode: "13.2.1"
             runs-on: macos-12
-          - swift: "5.4"
-            xcode: "12.5.1"
-            runs-on: macos-11
-          - swift: "5.3"
-            xcode: "12.4"
-            runs-on: macos-11
-          - swift: "5.2"
-            xcode: "11.7"
-            runs-on: macos-11
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Building in Swift ${{ matrix.swift }}
         run: xcodebuild -scheme FloatingPanel SWIFT_VERSION=${{ matrix.swift }} clean build
 
@@ -55,11 +49,11 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: "17.2"
-            xcode: "15.2"
+          - os: "17.5"
+            xcode: "15.4"
             sim: "iPhone 15 Pro"
             parallel: NO  # Stop random test job failures
-            runs-on: macos-13
+            runs-on: macos-14
           - os: "16.4"
             xcode: "14.3.1"
             sim: "iPhone 14 Pro"
@@ -71,7 +65,7 @@ jobs:
             parallel: NO  # Stop random test job failures
             runs-on: macos-12
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Testing in iOS ${{ matrix.os }}
       run: |
         xcodebuild clean test \
@@ -82,9 +76,9 @@ jobs:
     timeout-minutes: 20
 
   example:
-    runs-on: macos-13
+    runs-on: macos-14
     env:
-      DEVELOPER_DIR: /Applications/Xcode_15.2.app/Contents/Developer
+      DEVELOPER_DIR: /Applications/Xcode_15.4.app/Contents/Developer
     strategy:
       fail-fast: false
       matrix:
@@ -94,7 +88,7 @@ jobs:
           - example: "Stocks"
           - example: "Samples"
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Building ${{ matrix.example }}
       run: |
         xcodebuild clean build \
@@ -103,9 +97,9 @@ jobs:
           -sdk iphonesimulator
 
   swiftpm:
-    runs-on: macos-13
+    runs-on: macos-14
     env:
-      DEVELOPER_DIR: /Applications/Xcode_15.2.app/Contents/Developer
+      DEVELOPER_DIR: /Applications/Xcode_15.4.app/Contents/Developer
     strategy:
       fail-fast: false
       matrix:
@@ -121,7 +115,7 @@ jobs:
           - platform: iphonesimulator
             sys: "ios17.2-simulator"
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: "Swift Package Manager build"
       run: |
         xcrun swift build \
@@ -151,26 +145,19 @@ jobs:
             xcode: "14.1"
             runs-on: macos-12
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: "Swift Package Manager build"
       run: |
         swift build \
           -Xswiftc "-sdk" -Xswiftc "`xcrun --sdk iphonesimulator --show-sdk-path`" \
           -Xswiftc "-target" -Xswiftc "${{ matrix.target }}"
 
-  carthage:
-    runs-on: macos-11
-    steps:
-    - uses: actions/checkout@v3
-    - name: "Carthage build"
-      run: carthage build --use-xcframeworks --no-skip-current
-
   cocoapods:
-    runs-on: macos-13
+    runs-on: macos-14
     env:
-      DEVELOPER_DIR: /Applications/Xcode_15.2.app/Contents/Developer
+      DEVELOPER_DIR: /Applications/Xcode_15.4.app/Contents/Developer
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: "CocoaPods: pod lib lint"
       run: pod lib lint --allow-warnings
     - name: "CocoaPods: pod spec lint"

Examples/Samples/Samples.xcodeproj/project.pbxproj

@@ -18,7 +18,7 @@
 		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 */; };
-		544BC56826CC918200D0A436 /* AdaptiveLayoutTestViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 544BC56726CC918200D0A436 /* AdaptiveLayoutTestViewController.swift */; };
+		544BC56826CC918200D0A436 /* TableViewControllerForAdaptiveLayout.swift in Sources */ = {isa = PBXBuildFile; fileRef = 544BC56726CC918200D0A436 /* TableViewControllerForAdaptiveLayout.swift */; };
 		545DB9EE21511E6300CA77B8 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DB9ED21511E6300CA77B8 /* AppDelegate.swift */; };
 		545DB9F021511E6300CA77B8 /* MainViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 545DB9EF21511E6300CA77B8 /* MainViewController.swift */; };
 		545DB9F321511E6300CA77B8 /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 545DB9F121511E6300CA77B8 /* Main.storyboard */; };
@@ -30,8 +30,11 @@
 		549D23CC233C7779008EF4D7 /* FloatingPanel.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 549D23CA233C7779008EF4D7 /* FloatingPanel.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
 		54B51116216AFE5F0033A6F3 /* Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54B51115216AFE5F0033A6F3 /* Extensions.swift */; };
 		54CDC5D8215BBE23007D205C /* SupplementaryViews.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54CDC5D7215BBE23007D205C /* SupplementaryViews.swift */; };
+		54E58CB72BF8A8D900408EA9 /* CollectionViewControllerForAdaptiveLayout.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54E58CB62BF8A8D900408EA9 /* CollectionViewControllerForAdaptiveLayout.swift */; };
 		54EAD35B263A75EB006A36EA /* PanelLayouts.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54EAD35A263A75EB006A36EA /* PanelLayouts.swift */; };
 		54EAD365263A765F006A36EA /* PagePanelController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54EAD364263A765F006A36EA /* PagePanelController.swift */; };
+		54F185822BF4AD0000916F57 /* DebugListCollectionViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54F185812BF4AD0000916F57 /* DebugListCollectionViewController.swift */; };
+		54F185842BF4B82E00916F57 /* UnavailableViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 54F185832BF4B82E00916F57 /* UnavailableViewController.swift */; };
 		5D82A6AD28D1843C006A44BA /* libswiftCoreGraphics.tbd in Frameworks */ = {isa = PBXBuildFile; fileRef = 5D82A6AC28D18438006A44BA /* libswiftCoreGraphics.tbd */; };
 /* End PBXBuildFile section */
 
@@ -61,7 +64,7 @@
 		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>"; };
-		544BC56726CC918200D0A436 /* AdaptiveLayoutTestViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AdaptiveLayoutTestViewController.swift; sourceTree = "<group>"; };
+		544BC56726CC918200D0A436 /* TableViewControllerForAdaptiveLayout.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TableViewControllerForAdaptiveLayout.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 /* MainViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MainViewController.swift; sourceTree = "<group>"; };
@@ -74,8 +77,11 @@
 		549D23CA233C7779008EF4D7 /* FloatingPanel.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = FloatingPanel.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		54B51115216AFE5F0033A6F3 /* Extensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Extensions.swift; sourceTree = "<group>"; };
 		54CDC5D7215BBE23007D205C /* SupplementaryViews.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SupplementaryViews.swift; sourceTree = "<group>"; };
+		54E58CB62BF8A8D900408EA9 /* CollectionViewControllerForAdaptiveLayout.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CollectionViewControllerForAdaptiveLayout.swift; sourceTree = "<group>"; };
 		54EAD35A263A75EB006A36EA /* PanelLayouts.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PanelLayouts.swift; sourceTree = "<group>"; };
 		54EAD364263A765F006A36EA /* PagePanelController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PagePanelController.swift; sourceTree = "<group>"; };
+		54F185812BF4AD0000916F57 /* DebugListCollectionViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DebugListCollectionViewController.swift; sourceTree = "<group>"; };
+		54F185832BF4B82E00916F57 /* UnavailableViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UnavailableViewController.swift; sourceTree = "<group>"; };
 		5D82A6AC28D18438006A44BA /* libswiftCoreGraphics.tbd */ = {isa = PBXFileReference; lastKnownFileType = "sourcecode.text-based-dylib-definition"; name = libswiftCoreGraphics.tbd; path = usr/lib/swift/libswiftCoreGraphics.tbd; sourceTree = SDKROOT; };
 /* End PBXFileReference section */
 
@@ -95,17 +101,18 @@
 		5442E22225FC519700A26F43 /* ContentViewControllers */ = {
 			isa = PBXGroup;
 			children = (
+				54E58CB52BF8A88600408EA9 /* AdaptiveLayout */,
 				5442E23F25FC533800A26F43 /* DebugTableViewController.swift */,
 				5442E24925FC53C100A26F43 /* DebugTextViewController.swift */,
+				54F185812BF4AD0000916F57 /* DebugListCollectionViewController.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 */,
-				544BC56726CC918200D0A436 /* AdaptiveLayoutTestViewController.swift */,
+				54F185832BF4B82E00916F57 /* UnavailableViewController.swift */,
 			);
 			path = ContentViewControllers;
 			sourceTree = "<group>";
@@ -157,6 +164,16 @@
 			path = UseCases;
 			sourceTree = "<group>";
 		};
+		54E58CB52BF8A88600408EA9 /* AdaptiveLayout */ = {
+			isa = PBXGroup;
+			children = (
+				5442E22325FC51AF00A26F43 /* ImageViewController.swift */,
+				544BC56726CC918200D0A436 /* TableViewControllerForAdaptiveLayout.swift */,
+				54E58CB62BF8A8D900408EA9 /* CollectionViewControllerForAdaptiveLayout.swift */,
+			);
+			path = AdaptiveLayout;
+			sourceTree = "<group>";
+		};
 		5D82A6AB28D18438006A44BA /* Frameworks */ = {
 			isa = PBXGroup;
 			children = (
@@ -238,15 +255,17 @@
 			buildActionMask = 2147483647;
 			files = (
 				5442E23425FC528400A26F43 /* DetailViewController.swift in Sources */,
+				54E58CB72BF8A8D900408EA9 /* CollectionViewControllerForAdaptiveLayout.swift in Sources */,
 				54496C59263A7E5A0031E0C8 /* UseCaseController.swift in Sources */,
 				54CDC5D8215BBE23007D205C /* SupplementaryViews.swift in Sources */,
 				54B51116216AFE5F0033A6F3 /* Extensions.swift in Sources */,
-				544BC56826CC918200D0A436 /* AdaptiveLayoutTestViewController.swift in Sources */,
+				544BC56826CC918200D0A436 /* TableViewControllerForAdaptiveLayout.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 */,
+				54F185822BF4AD0000916F57 /* DebugListCollectionViewController.swift in Sources */,
 				5442E25225FC541700A26F43 /* NestedScrollViewController.swift in Sources */,
 				5442E22825FC51E200A26F43 /* MultiPanelController.swift in Sources */,
 				546341A125C6415100CA0596 /* UseCase.swift in Sources */,
@@ -257,6 +276,7 @@
 				54EAD365263A765F006A36EA /* PagePanelController.swift in Sources */,
 				5442E24425FC538200A26F43 /* InspectorViewController.swift in Sources */,
 				5442E22C25FC521F00A26F43 /* SettingsViewController.swift in Sources */,
+				54F185842BF4B82E00916F57 /* UnavailableViewController.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

Examples/Samples/Sources/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="21701" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="RoN-h0-uBD">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="32700.99.1234" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="RoN-h0-uBD">
     <device id="retina6_1" orientation="portrait" appearance="light"/>
     <dependencies>
         <deployment identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="21679"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="22685"/>
         <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"/>
@@ -801,10 +801,10 @@ Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
             </objects>
             <point key="canvasLocation" x="-2.1739130434782612" y="733.92857142857144"/>
         </scene>
-        <!--Adaptive Layout Test View Controller-->
+        <!--Table View Controller For Adaptive Layout-->
         <scene sceneID="rDI-lU-wEx">
             <objects>
-                <viewController storyboardIdentifier="AdaptiveLayoutTestViewController" id="5nC-6E-bXf" customClass="AdaptiveLayoutTestViewController" customModule="Samples" customModuleProvider="target" sceneMemberID="viewController">
+                <viewController storyboardIdentifier="TableViewControllerForAdaptiveLayout" id="5nC-6E-bXf" customClass="TableViewControllerForAdaptiveLayout" customModule="Samples" customModuleProvider="target" sceneMemberID="viewController">
                     <view key="view" contentMode="scaleToFill" id="jXL-Ss-NCJ">
                         <rect key="frame" x="0.0" y="0.0" width="375" height="778"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
@@ -861,13 +861,13 @@ Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
             <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"/>
+            <color red="1" green="0.58431372550000005" 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"/>
+            <color red="0.68627450980000004" green="0.32156862749999998" blue="0.87058823529999996" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
         </systemColor>
         <systemColor name="systemTealColor">
-            <color red="0.18823529411764706" green="0.69019607843137254" blue="0.7803921568627451" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+            <color red="0.18823529410000001" green="0.69019607839999997" blue="0.78039215689999997" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
         </systemColor>
     </resources>
 </document>

Examples/Samples/Sources/ContentViewControllers/AdaptiveLayout/CollectionViewControllerForAdaptiveLayout.swift

@@ -0,0 +1,175 @@
+// Copyright 2018-Present Shin Yamamoto. All rights reserved. MIT license.
+
+import UIKit
+import FloatingPanel
+
+@available(iOS 13.0, *)
+class CollectionViewControllerForAdaptiveLayout: UIViewController {
+    class PanelLayout: FloatingPanelLayout {
+        let position: FloatingPanelPosition = .bottom
+        let initialState: FloatingPanelState = .full
+
+        private unowned var targetGuide: UILayoutGuide
+
+        init(targetGuide: UILayoutGuide) {
+            self.targetGuide = targetGuide
+        }
+
+        var anchors: [FloatingPanelState : FloatingPanelLayoutAnchoring] {
+            return [
+                .full: FloatingPanelAdaptiveLayoutAnchor(
+                    absoluteOffset: 0.0,
+                    contentLayout: targetGuide,
+                    referenceGuide: .superview,
+                    contentBoundingGuide: .safeArea
+                ),
+                .half: FloatingPanelAdaptiveLayoutAnchor(
+                    fractionalOffset: 0.5,
+                    contentLayout: targetGuide,
+                    referenceGuide: .superview,
+                    contentBoundingGuide: .safeArea
+                ),
+            ]
+        }
+    }
+
+    enum LayoutType {
+        case flow
+        case compositional
+    }
+
+    weak var collectionView: UICollectionView!
+    var layoutType: LayoutType = .flow
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        setupCollectionView()
+    }
+
+    private func setupCollectionView() {
+        let collectionViewLayout = {
+            switch layoutType {
+            case .flow:
+                CollectionViewLayoutFactory.flowLayout
+            case .compositional:
+                CollectionViewLayoutFactory.compositionalLayout
+            }
+        }()
+        let collectionView = IntrinsicCollectionView(
+            frame: .zero,
+            collectionViewLayout: collectionViewLayout
+        )
+
+        collectionView.delegate = self
+        collectionView.dataSource = self
+        collectionView.backgroundColor = .yellow
+        collectionView.register(Cell.self, forCellWithReuseIdentifier: Cell.reuseIdentifier)
+
+        view.addSubview(collectionView)
+        self.collectionView = collectionView
+
+        collectionView.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            collectionView.topAnchor.constraint(equalTo: view.topAnchor),
+            collectionView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+            collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            collectionView.trailingAnchor.constraint(equalTo: view.trailingAnchor)
+        ])
+    }
+}
+
+@available(iOS 13.0, *)
+extension CollectionViewControllerForAdaptiveLayout: UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
+    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
+        return 5  // Only three cells needed to fill the space
+    }
+
+    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
+        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: Cell.reuseIdentifier, for: indexPath) as! Cell
+        cell.configure(text: "Item \(indexPath.row)")
+        return cell
+    }
+
+
+    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
+        let width = collectionView.frame.width  
+        return CGSize(width: width, height: 100)
+    }
+}
+
+@available(iOS 13.0, *)
+extension CollectionViewControllerForAdaptiveLayout {
+    enum CollectionViewLayoutFactory {
+        static var flowLayout: UICollectionViewLayout {
+            let layout = UICollectionViewFlowLayout()
+            layout.scrollDirection = .vertical
+            layout.minimumLineSpacing = 8  // Vertical spacing between rows
+            return layout
+        }
+
+        @available(iOS 13.0, *)
+        static var compositionalLayout: UICollectionViewLayout {
+            UICollectionViewCompositionalLayout { (sectionIndex: Int, layoutEnvironment: NSCollectionLayoutEnvironment) -> NSCollectionLayoutSection? in
+                let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0), heightDimension: .absolute(100))
+                let item = NSCollectionLayoutItem(layoutSize: itemSize)
+
+                let group = NSCollectionLayoutGroup.horizontal(layoutSize: itemSize, subitems: [item])
+
+                let section = NSCollectionLayoutSection(group: group)
+                section.interGroupSpacing = 8 // Spacing between each group/item
+                section.contentInsets = NSDirectionalEdgeInsets(top: 0, leading: 0, bottom: 0, trailing: 0)
+
+                return section
+            }
+        }
+    }
+
+
+    private final class Cell: UICollectionViewCell {
+        static let reuseIdentifier = "Cell"
+
+        private let label: UILabel = {
+            let label = UILabel()
+            label.textAlignment = .center
+            label.textColor = .white
+            return label
+        }()
+
+        override init(frame: CGRect) {
+            super.init(frame: frame)
+            commonInit()
+        }
+
+        required init?(coder: NSCoder) {
+            super.init(coder: coder)
+            commonInit()
+        }
+
+        private func commonInit() {
+            backgroundColor = .systemBlue
+            addSubview(label)
+            label.translatesAutoresizingMaskIntoConstraints = false
+            NSLayoutConstraint.activate([
+                label.centerXAnchor.constraint(equalTo: centerXAnchor),
+                label.centerYAnchor.constraint(equalTo: centerYAnchor)
+            ])
+        }
+
+        func configure(text: String) {
+            label.text = text
+        }
+    }
+
+    private final class IntrinsicCollectionView: UICollectionView {
+        override public var contentSize: CGSize {
+            didSet {
+                invalidateIntrinsicContentSize()
+            }
+        }
+
+        override public var intrinsicContentSize: CGSize {
+            layoutIfNeeded()
+            return CGSize(width: UIView.noIntrinsicMetric, height: contentSize.height)
+        }
+    }
+}

Examples/Samples/Sources/ContentViewControllers/AdaptiveLayout/TableViewControllerForAdaptiveLayout.swift

@@ -3,7 +3,7 @@
 import UIKit
 import FloatingPanel
 
-final class AdaptiveLayoutTestViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
+final class TableViewControllerForAdaptiveLayout: UIViewController, UITableViewDataSource, UITableViewDelegate {
     class PanelLayout: FloatingPanelLayout {
         let position: FloatingPanelPosition = .bottom
         let initialState: FloatingPanelState = .full
@@ -75,7 +75,6 @@ final class AdaptiveLayoutTestViewController: UIViewController, UITableViewDataS
 }
 
 class IntrinsicTableView: UITableView {
-
     override var contentSize:CGSize {
         didSet {
             invalidateIntrinsicContentSize()

Examples/Samples/Sources/ContentViewControllers/DebugListCollectionViewController.swift

@@ -0,0 +1,77 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+
+@available(iOS 14, *)
+class DebugListCollectionViewController: UIViewController {
+
+    enum Section {
+        case main
+    }
+
+    var dataSource: UICollectionViewDiffableDataSource<Section, Int>! = nil
+    var collectionView: UICollectionView! = nil
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        navigationItem.title = "List"
+        configureHierarchy()
+        configureDataSource()
+    }
+}
+
+@available(iOS 14, *)
+extension DebugListCollectionViewController {
+    /// - Tag: List
+    private func createLayout() -> UICollectionViewLayout {
+        var config = UICollectionLayoutListConfiguration(appearance: .insetGrouped)
+        config.trailingSwipeActionsConfigurationProvider =  { indexPath -> UISwipeActionsConfiguration? in
+            return UISwipeActionsConfiguration(
+                actions: [UIContextualAction(
+                    style: .destructive,
+                    title: "Delete",
+                    handler: { _, _, completion in
+                        // Do nothing now
+                    }
+                )]
+            )
+        }
+        return UICollectionViewCompositionalLayout.list(using: config)
+    }
+}
+
+@available(iOS 14, *)
+extension DebugListCollectionViewController {
+    private func configureHierarchy() {
+        collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: createLayout())
+        collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
+        view.addSubview(collectionView)
+        collectionView.delegate = self
+    }
+    private func configureDataSource() {
+
+        let cellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, Int> { (cell, indexPath, item) in
+            var content = cell.defaultContentConfiguration()
+            content.text = "\(item)"
+            cell.contentConfiguration = content
+        }
+
+        dataSource = UICollectionViewDiffableDataSource<Section, Int>(collectionView: collectionView) {
+            (collectionView: UICollectionView, indexPath: IndexPath, identifier: Int) -> UICollectionViewCell? in
+
+            return collectionView.dequeueConfiguredReusableCell(using: cellRegistration, for: indexPath, item: identifier)
+        }
+
+        var snapshot = NSDiffableDataSourceSnapshot<Section, Int>()
+        snapshot.appendSections([.main])
+        snapshot.appendItems(Array(0..<94))
+        dataSource.apply(snapshot, animatingDifferences: false)
+    }
+}
+
+@available(iOS 14, *)
+extension DebugListCollectionViewController: UICollectionViewDelegate {
+    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
+        collectionView.deselectItem(at: indexPath, animated: true)
+    }
+}

Examples/Samples/Sources/ContentViewControllers/UnavailableViewController.swift

@@ -0,0 +1,24 @@
+// Copyright 2018 the FloatingPanel authors. All rights reserved. MIT license.
+
+import UIKit
+
+class UnavailableViewController: UIViewController {
+    weak var label: UILabel!
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        let label = UILabel()
+        label.text = "Unavailable content"
+        label.numberOfLines = 0
+        label.textAlignment = .center
+        label.frame = view.bounds
+        label.autoresizingMask = [
+            .flexibleTopMargin,
+            .flexibleLeftMargin,
+            .flexibleBottomMargin,
+            .flexibleRightMargin
+        ]
+        view.addSubview(label)
+        self.label = label
+    }
+}

Examples/Samples/Sources/UseCases/UseCase.swift

@@ -5,6 +5,7 @@ import UIKit
 enum UseCase: Int, CaseIterable {
     case trackingTableView
     case trackingTextView
+    case trackingCollectionViewList
     case showDetail
     case showModal
     case showPanelModal
@@ -22,7 +23,9 @@ enum UseCase: Int, CaseIterable {
     case showNavigationController
     case showTopPositionedPanel
     case showAdaptivePanel
-    case showAdaptivePanelWithCustomGuide
+    case showAdaptivePanelWithTableView
+    case showAdaptivePanelWithCollectionView
+    case showAdaptivePanelWithCompositionalCollectionView
     case showCustomStatePanel
     case showCustomBackdrop
 }
@@ -31,6 +34,7 @@ extension UseCase {
     var name: String {
         switch self {
         case .trackingTableView: return "Scroll tracking(TableView)"
+        case .trackingCollectionViewList: return "Scroll tracking(List CollectionView)"
         case .trackingTextView: return "Scroll tracking(TextView)"
         case .showDetail: return "Show Detail Panel"
         case .showModal: return "Show Modal"
@@ -49,7 +53,9 @@ extension UseCase {
         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 .showAdaptivePanelWithTableView: return "Show Adaptive Panel (TableView)"
+        case .showAdaptivePanelWithCollectionView: return "Show Adaptive Panel (CollectionView)"
+        case .showAdaptivePanelWithCompositionalCollectionView: return "Show Adaptive Panel (Compositional CollectionView)"
         case .showCustomStatePanel: return "Show Panel with Custom state"
         case .showCustomBackdrop: return "Show Panel with Custom Backdrop"
         }
@@ -65,6 +71,13 @@ extension UseCase {
     private var content: Content {
         switch self {
         case .trackingTableView: return .viewController(DebugTableViewController())
+        case .trackingCollectionViewList:
+            if #available(iOS 14, *) {
+                return .viewController(DebugListCollectionViewController())
+            } else {
+                let msg = "UICollectionLayoutListConfiguration is unavailable.\nBuild this app on iOS 14 and later."
+                return makeUnavailableViewContent(message: msg)
+            }
         case .trackingTextView: return .storyboard("ConsoleViewController") // Storyboard only
         case .showDetail: return .storyboard(String(describing: DetailViewController.self))
         case .showModal: return .storyboard(String(describing: ModalViewController.self))
@@ -83,7 +96,17 @@ extension UseCase {
         case .showNavigationController: return .storyboard("RootNavigationController") // Storyboard only
         case .showTopPositionedPanel: return .viewController(DebugTableViewController())
         case .showAdaptivePanel: return .storyboard(String(describing: ImageViewController.self))
-        case .showAdaptivePanelWithCustomGuide: return .storyboard(String(describing: AdaptiveLayoutTestViewController.self))
+        case .showAdaptivePanelWithTableView: return .storyboard(String(describing: TableViewControllerForAdaptiveLayout.self))
+        case .showAdaptivePanelWithCollectionView,
+            .showAdaptivePanelWithCompositionalCollectionView:
+            if #available(iOS 13, *) {
+                let vc = CollectionViewControllerForAdaptiveLayout()
+                vc.layoutType = self == .showAdaptivePanelWithCollectionView ? .flow : .compositional
+                return .viewController(vc)
+            } else {
+                let msg = "Compositional layout is unavailable.\nBuild this app on iOS 13 and later."
+                return makeUnavailableViewContent(message: msg)
+            }
         case .showCustomStatePanel: return .viewController(DebugTableViewController())
         case .showCustomBackdrop: return .viewController(UIViewController())
         }
@@ -98,4 +121,11 @@ extension UseCase {
             return vc
         }
     }
+
+    private func makeUnavailableViewContent(message: String) -> Content {
+        let vc = UnavailableViewController()
+        vc.loadViewIfNeeded()
+        vc.label.text = message
+        return .viewController(vc)
+    }
 }

Examples/Samples/Sources/UseCases/UseCaseController.swift

@@ -52,6 +52,30 @@ extension UseCaseController {
             fpc.ext_trackScrollView(in: contentVC)
             addMain(panel: fpc)
 
+         case .trackingCollectionViewList:
+            let fpc = FloatingPanelController()
+            fpc.delegate = self
+            fpc.contentInsetAdjustmentBehavior = .always
+            fpc.surfaceView.appearance = {
+                let appearance = SurfaceAppearance()
+                appearance.cornerRadius = 6.0
+                return appearance
+            }()
+
+            let tapGesture = UITapGestureRecognizer(target: self, 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
+            fpc.surfaceView.addGestureRecognizer(tapGesture)
+
+            fpc.set(contentViewController: contentVC)
+            if #available(iOS 14, *),
+                let scrollView = (fpc.contentViewController as? DebugListCollectionViewController)?.collectionView {
+                    fpc.track(scrollView: scrollView)
+            }
+            addMain(panel: fpc)
+
         case .trackingTextView:
             let fpc = FloatingPanelController()
             fpc.delegate = self
@@ -239,13 +263,13 @@ extension UseCaseController {
             fpc.set(contentViewController: contentVC)
             fpc.ext_trackScrollView(in: contentVC)
             if case let contentVC as ImageViewController = contentVC {
-                let mode: ImageViewController.Mode = (useCase == .showAdaptivePanelWithCustomGuide) ? .withHeaderFooter : .onlyImage
+                let mode: ImageViewController.Mode = (useCase == .showAdaptivePanelWithTableView) ? .withHeaderFooter : .onlyImage
                 let layoutGuide = contentVC.layoutGuideFor(mode: mode)
                 fpc.layout = ImageViewController.PanelLayout(targetGuide: layoutGuide)
             }
             addMain(panel: fpc)
 
-        case .showAdaptivePanelWithCustomGuide:
+        case .showAdaptivePanelWithTableView:
             let fpc = FloatingPanelController()
             fpc.isRemovalInteractionEnabled = true
             fpc.contentInsetAdjustmentBehavior = .always
@@ -255,10 +279,25 @@ extension UseCaseController {
                 return appearance
             }()
 
-
             fpc.set(contentViewController: contentVC)
-            fpc.ext_trackScrollView(in: contentVC)
-            fpc.layout = AdaptiveLayoutTestViewController.PanelLayout(targetGuide: contentVC.view.makeBoundsLayoutGuide())
+            fpc.track(scrollView: (contentVC as! TableViewControllerForAdaptiveLayout).tableView)
+            fpc.layout = TableViewControllerForAdaptiveLayout.PanelLayout(targetGuide: contentVC.view.makeBoundsLayoutGuide())
+            addMain(panel: fpc)
+
+        case .showAdaptivePanelWithCollectionView, .showAdaptivePanelWithCompositionalCollectionView:
+            let fpc = FloatingPanelController()
+            fpc.isRemovalInteractionEnabled = true
+            fpc.contentInsetAdjustmentBehavior = .always
+            fpc.surfaceView.appearance = {
+                let appearance = SurfaceAppearance()
+                appearance.cornerRadius = 6.0
+                return appearance
+            }()
+            fpc.set(contentViewController: contentVC)
+            if #available(iOS 13, *) {
+                fpc.track(scrollView: (contentVC as! CollectionViewControllerForAdaptiveLayout).collectionView)
+                fpc.layout = CollectionViewControllerForAdaptiveLayout.PanelLayout(targetGuide: contentVC.view.makeBoundsLayoutGuide())
+            }
             addMain(panel: fpc)
 
         case .showCustomStatePanel:
@@ -458,7 +497,7 @@ private extension FloatingPanelController {
         case let contentVC as ImageViewController:
             track(scrollView: contentVC.scrollView)
 
-        case let contentVC as AdaptiveLayoutTestViewController:
+        case let contentVC as TableViewControllerForAdaptiveLayout:
             track(scrollView: contentVC.tableView)
 
         default:

FloatingPanel.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
 
   s.name                = "FloatingPanel"
-  s.version             = "2.8.2"
+  s.version             = "2.8.5"
   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.

README.md

@@ -2,14 +2,13 @@
 [![Platform](https://img.shields.io/cocoapods/p/FloatingPanel.svg)](https://cocoapods.org/pods/FloatingPanel)
 [![Version](https://img.shields.io/cocoapods/v/FloatingPanel.svg)](https://cocoapods.org/pods/FloatingPanel)
 ![GitHub Workflow Status (with branch)](https://img.shields.io/github/actions/workflow/status/scenee/FloatingPanel/ci.yml?branch=master)
-[![Carthage compatible](https://img.shields.io/badge/carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)
 
 # FloatingPanel
 
 FloatingPanel is a simple and easy-to-use UI component designed for a user interface featured in Apple Maps, Shortcuts and Stocks app.
 The user interface displays related content and utilities alongside the main content.
 
-Please see also [the API reference@SPI](https://swiftpackageindex.com/scenee/FloatingPanel/2.8.2/documentation/floatingpanel) for more details.
+Please see also [the API reference@SPI](https://swiftpackageindex.com/scenee/FloatingPanel/2.8.5/documentation/floatingpanel) for more details.
 
 ![Maps](https://github.com/SCENEE/FloatingPanel/blob/master/assets/maps.gif)
 ![Stocks](https://github.com/SCENEE/FloatingPanel/blob/master/assets/stocks.gif)
@@ -22,7 +21,6 @@ Please see also [the API reference@SPI](https://swiftpackageindex.com/scenee/Flo
 - [Requirements](#requirements)
 - [Installation](#installation)
   - [CocoaPods](#cocoapods)
-  - [Carthage](#carthage)
   - [Swift Package Manager](#swift-package-manager)
 - [Getting Started](#getting-started)
   - [Add a floating panel as a child view controller](#add-a-floating-panel-as-a-child-view-controller)
@@ -104,14 +102,6 @@ it, simply add the following line to your Podfile:
 pod 'FloatingPanel'
 ```
 
-### Carthage
-
-For [Carthage](https://github.com/Carthage/Carthage), add the following to your `Cartfile`:
-
-```ogdl
-github "scenee/FloatingPanel"
-```
-
 ### Swift Package Manager
 
 Follow [this doc](https://developer.apple.com/documentation/swift_packages/adding_package_dependencies_to_your_app).

Sources/Core.swift

@@ -588,11 +588,16 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         // When no scrollView, nothing to handle.
         guard let scrollView = scrollView, scrollView.frame.contains(initialLocation) else { return false }
 
-        // For _UISwipeActionPanGestureRecognizer
-        if let scrollGestureRecognizers = scrollView.gestureRecognizers {
+        // Prevents moving a panel on swipe actions using _UISwipeActionPanGestureRecognizer.
+        // [Warning] Do not apply this to WKWebView. Since iOS 17.4, WKWebView has an additional pan
+        // gesture recognizer besides UIScrollViewPanGestureRecognizer. Applying this to WKWebView
+        // will block panel movements because another pan gesture isn't `scrollView.panGestureRecognizer`.
+        if let scrollGestureRecognizers = scrollView.gestureRecognizers,
+            scrollView is UITableView || scrollView is UICollectionView {
             for gesture in scrollGestureRecognizers {
-                guard gesture.state == .began || gesture.state == .changed
-                else { continue }
+                guard gesture.state == .began || gesture.state == .changed else {
+                    continue
+                }
 
                 if gesture != scrollView.panGestureRecognizer {
                     return true
@@ -651,14 +656,19 @@ class Core: NSObject, UIGestureRecognizerDelegate {
     }
 
     private func panningChange(with translation: CGPoint) {
-        os_log(msg, log: devLog, type: .debug, "panningChange -- translation = \(value(of: translation))")
         let pre = value(of: layoutAdapter.surfaceLocation)
         let diff = value(of: translation - initialTranslation)
         let next = pre + diff
 
-        layoutAdapter.updateInteractiveEdgeConstraint(diff: diff,
-                                                      scrollingContent: shouldScrollingContentInMoving(from: pre, to: next),
-                                                      allowsRubberBanding: behaviorAdapter.allowsRubberBanding(for:))
+        os_log(msg, log: devLog, type: .debug, """
+        panningChange -- translation = \(value(of: translation)), diff = \(diff), pre = \(pre), next = \(next)
+        """)
+
+        layoutAdapter.updateInteractiveEdgeConstraint(
+            diff: diff,
+            scrollingContent: shouldScrollingContentInMoving(from: pre, to: next),
+            allowsRubberBanding: behaviorAdapter.allowsRubberBanding(for:)
+        )
 
         let cur = value(of: layoutAdapter.surfaceLocation)
 
@@ -671,31 +681,36 @@ class Core: NSObject, UIGestureRecognizerDelegate {
         }
     }
 
-    private func shouldScrollingContentInMoving(from pre: CGFloat, to next: CGFloat) -> Bool {
+    /// Determines if the content should scroll while the surface is moving from `cur` to `target`.
+    ///
+    /// - Note: `cur` argument starts from an anchor location of surface view in a state. For example,
+    /// it starts from zero if the state is full whose FloatingPanelLayoutAnchor.absoluteInset is zero
+    /// and there is no additional safe area insets like a navigation bar. Therefore, `cur` argument
+    /// can be minus if the absoluteInset is minus with such a condition.
+    private func shouldScrollingContentInMoving(from cur: CGFloat, to target: CGFloat) -> Bool {
         // Don't allow scrolling if the initial panning location is in the grabber area.
         if surfaceView.grabberAreaContains(initialLocation) {
             return false
         }
-        if let scrollView = scrollView, scrollView.panGestureRecognizer.state == .changed {
+        if let sv = scrollView, sv.panGestureRecognizer.state == .changed {
+            let (contentSize, bounds, alwaysBounceHorizontal, alwaysBounceVertical)
+                = (sv.contentSize, sv.bounds, sv.alwaysBounceHorizontal, sv.alwaysBounceVertical)
+
             switch layoutAdapter.position {
             case .top:
-                if pre > .zero, pre < next,
-                    scrollView.contentSize.height > scrollView.bounds.height || scrollView.alwaysBounceVertical {
+                if cur < target, contentSize.height > bounds.height || alwaysBounceVertical {
                     return true
                 }
             case .left:
-                if pre > .zero, pre < next,
-                    scrollView.contentSize.width > scrollView.bounds.width || scrollView.alwaysBounceHorizontal {
+                if cur < target, contentSize.width > bounds.width || alwaysBounceHorizontal {
                     return true
                 }
             case .bottom:
-                if pre > .zero, pre > next,
-                    scrollView.contentSize.height > scrollView.bounds.height || scrollView.alwaysBounceVertical {
+                if cur > target, contentSize.height > bounds.height || alwaysBounceVertical {
                     return true
                 }
             case .right:
-                if pre > .zero, pre > next,
-                    scrollView.contentSize.width > scrollView.bounds.width || scrollView.alwaysBounceHorizontal {
+                if cur > target, contentSize.width > bounds.width || alwaysBounceHorizontal {
                     return true
                 }
             }

Sources/Info.plist

@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>2.8.2</string>
+	<string>2.8.5</string>
 	<key>CFBundleVersion</key>
 	<string>$(CURRENT_PROJECT_VERSION)</string>
 </dict>

Sources/LayoutAnchoring.swift

@@ -17,7 +17,7 @@ import UIKit
     /// positioning.
     ///
     /// - Parameters:
-    ///     - absoluteOffset: An absolute offset to attach the panel from the edge.
+    ///     - absoluteInset: An absolute distance to attach the panel from the specified edge.
     ///     - edge: Specify the edge of ``FloatingPanelController``'s view. This is the staring point of the offset.
     ///     - referenceGuide: The rectangular area to lay out the content. If it's set to `.safeArea`, the panel content lays out inside the safe area of its ``FloatingPanelController``'s view.
     @objc public init(absoluteInset: CGFloat, edge: FloatingPanelReferenceEdge, referenceGuide: FloatingPanelLayoutReferenceGuide) {
@@ -34,7 +34,7 @@ import UIKit
     /// 1.0 represents a distance to the opposite edge.
     ///
     /// - Parameters:
-    ///     - fractionalOffset: A fractional value of the size of ``FloatingPanelController``'s view to attach the panel from the edge.
+    ///     - fractionalInset: A fractional value of the size of ``FloatingPanelController``'s view to attach the panel from the specified edge.
     ///     - edge: Specify the edge of ``FloatingPanelController``'s view. This is the staring point of the offset.
     ///     - referenceGuide: The rectangular area to lay out the content. If it's set to `.safeArea`, the panel content lays out inside the safe area of its ``FloatingPanelController``'s view.
     @objc public init(fractionalInset: CGFloat, edge: FloatingPanelReferenceEdge, referenceGuide: FloatingPanelLayoutReferenceGuide) {
@@ -115,8 +115,8 @@ public extension FloatingPanelLayoutAnchor {
     /// - Parameters:
     ///     - absoluteOffset: An absolute offset from the content size in the main dimension(i.e. y axis for a bottom panel) to attach the panel.
     ///     - referenceGuide: The rectangular area to lay out the content. If it's set to `.safeArea`, the panel content lays out inside the safe area of its ``FloatingPanelController``'s view.
-    @objc public init(absoluteOffset offset: CGFloat, referenceGuide: FloatingPanelLayoutReferenceGuide = .safeArea) {
-        self.offset = offset
+    @objc public init(absoluteOffset: CGFloat, referenceGuide: FloatingPanelLayoutReferenceGuide = .safeArea) {
+        self.offset = absoluteOffset
         self.referenceGuide = referenceGuide
         self.isAbsolute = true
     }
@@ -129,8 +129,8 @@ public extension FloatingPanelLayoutAnchor {
     /// - Parameters:
     ///     - fractionalOffset: A fractional offset of the content size in the main dimension(i.e. y axis for a bottom panel) to attach the panel.
     ///     - referenceGuide: The rectangular area to lay out the content. If it's set to `.safeArea`, the panel content lays out inside the safe area of its ``FloatingPanelController``'s view.
-    @objc public init(fractionalOffset offset: CGFloat, referenceGuide: FloatingPanelLayoutReferenceGuide = .safeArea) {
-        self.offset = offset
+    @objc public init(fractionalOffset: CGFloat, referenceGuide: FloatingPanelLayoutReferenceGuide = .safeArea) {
+        self.offset = fractionalOffset
         self.referenceGuide = referenceGuide
         self.isAbsolute = false
     }
@@ -177,12 +177,12 @@ public extension FloatingPanelIntrinsicLayoutAnchor {
     ///
     /// - Warning: If ``contentBoundingGuide`` is set to none, the panel may expand out of the screen size, depending on the intrinsic size of its content.
     @objc public init(
-        absoluteOffset offset: CGFloat,
+        absoluteOffset: CGFloat,
         contentLayout: UILayoutGuide,
         referenceGuide: FloatingPanelLayoutReferenceGuide,
         contentBoundingGuide: FloatingPanelLayoutContentBoundingGuide = .none
     ) {
-        self.offset = offset
+        self.offset = absoluteOffset
         self.contentLayoutGuide = contentLayout
         self.referenceGuide = referenceGuide
         self.contentBoundingGuide = contentBoundingGuide
@@ -204,12 +204,12 @@ public extension FloatingPanelIntrinsicLayoutAnchor {
     ///
     /// - Warning: If ``contentBoundingGuide`` is set to none, the panel may expand out of the screen size, depending on the intrinsic size of its content.
     @objc public init(
-        fractionalOffset offset: CGFloat,
+        fractionalOffset: CGFloat,
         contentLayout: UILayoutGuide,
         referenceGuide: FloatingPanelLayoutReferenceGuide,
         contentBoundingGuide: FloatingPanelLayoutContentBoundingGuide = .none
     ) {
-        self.offset = offset
+        self.offset = fractionalOffset
         self.contentLayoutGuide = contentLayout
         self.referenceGuide = referenceGuide
         self.contentBoundingGuide = contentBoundingGuide

Sources/SurfaceView.swift

@@ -56,11 +56,11 @@ public class SurfaceAppearance: NSObject {
     /// Defaults to `.circular`.
     @available(iOS 13.0, *)
     public var cornerCurve: CALayerCornerCurve {
-        get { _cornerCurve ?? .circular }
+        get { _cornerCurve as? CALayerCornerCurve ?? .circular }
         set { _cornerCurve = newValue }
     }
 
-    private var _cornerCurve: CALayerCornerCurve?
+    private var _cornerCurve: Any?
 
     /// An array of shadows used to create drop shadows underneath a surface view.
     public var shadows: [Shadow] = [Shadow()]
@@ -418,12 +418,30 @@ public class SurfaceView: UIView {
         let leftConstraint = contentView.leftAnchor.constraint(equalTo: leftAnchor, constant: containerMargins.left + contentPadding.left)
         let rightConstraint = rightAnchor.constraint(equalTo: contentView.rightAnchor, constant: containerMargins.right + contentPadding.right)
         let bottomConstraint = bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: containerMargins.bottom + contentPadding.bottom)
-        NSLayoutConstraint.activate([
+
+        var constraints = [
             topConstraint,
             leftConstraint,
             rightConstraint,
-            bottomConstraint,
-        ].map {
+            bottomConstraint
+        ]
+
+        // This constraint is for UICollectionView using UICollectionViewCompositionalLayout.
+        // It's seemingly obvious, but the UICollectionView doesn't work without setting it. (#628)
+        switch position {
+        case .top, .bottom:
+            constraints += [
+                heightAnchor.constraint(greaterThanOrEqualToConstant: 1.0)
+            ]
+        case .left, .right:
+            constraints += [
+                widthAnchor.constraint(greaterThanOrEqualToConstant: 1.0)
+            ]
+        }
+
+        NSLayoutConstraint.activate(
+            constraints
+            .map {
             switch mode {
             case .static:
                 $0.priority = .required

Sources/Transitioning.swift

@@ -84,7 +84,7 @@ class ModalPresentTransition: NSObject, UIViewControllerAnimatedTransitioning {
     func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
         guard
             let fpc = transitionContext?.viewController(forKey: .to) as? FloatingPanelController
-        else { fatalError()}
+        else { return 0.0 }
 
         let animator = fpc.animatorForPresenting(to: fpc.layout.initialState)
         return TimeInterval(animator.duration)
@@ -119,7 +119,7 @@ class ModalDismissTransition: NSObject, UIViewControllerAnimatedTransitioning {
     func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
         guard
             let fpc = transitionContext?.viewController(forKey: .from) as? FloatingPanelController
-        else { fatalError()}
+        else { return 0.0 }
 
         let animator = fpc.animatorForDismissing(with: .zero)
         return TimeInterval(animator.duration)

Tests/ControllerTests.swift

@@ -64,6 +64,7 @@ class ControllerTests: XCTestCase {
     }
 
     func test_moveTo() {
+        let timeout = 3.0
         let delegate = FloatingPanelTestDelegate()
         let fpc = FloatingPanelController(delegate: delegate)
         XCTAssertEqual(delegate.position, .hidden)
@@ -102,7 +103,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .full)
             XCTAssertEqual(delegate.position, .full)
-            wait(for: [exp], timeout: 1.0)
+            wait(for: [exp], timeout: timeout)
         }
 
         XCTContext.runActivity(named: "move to half(animated)") { act in
@@ -113,7 +114,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .half)
             XCTAssertEqual(delegate.position, .half)
-            wait(for: [exp], timeout: 1.0)
+            wait(for: [exp], timeout: timeout)
         }
 
         XCTContext.runActivity(named: "move to tip(animated)") { act in
@@ -124,7 +125,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .tip)
             XCTAssertEqual(delegate.position, .tip)
-            wait(for: [exp], timeout: 1.0)
+            wait(for: [exp], timeout: timeout)
         }
 
         fpc.move(to: .hidden, animated: true)
@@ -137,6 +138,7 @@ class ControllerTests: XCTestCase {
         class MyFloatingPanelTop2BottomLayout: FloatingPanelTop2BottomTestLayout {
             override var initialState: FloatingPanelState { return .half }
         }
+        let timeout = 3.0
         let delegate = FloatingPanelTestDelegate()
         let fpc = FloatingPanelController(delegate: delegate)
         fpc.layout = MyFloatingPanelTop2BottomLayout()
@@ -175,7 +177,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .full)
             XCTAssertEqual(delegate.position, .full)
-            wait(for: [exp], timeout: 1.0)
+            wait(for: [exp], timeout: timeout)
         }
 
         XCTContext.runActivity(named: "move to half(animated)") { act in
@@ -186,7 +188,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .half)
             XCTAssertEqual(delegate.position, .half)
-            wait(for: [exp], timeout: 1.0)
+            wait(for: [exp], timeout: timeout)
         }
 
         XCTContext.runActivity(named: "move to tip(animated)") { act in
@@ -197,7 +199,7 @@ class ControllerTests: XCTestCase {
             }
             XCTAssertEqual(fpc.state, .tip)
             XCTAssertEqual(delegate.position, .tip)
-            wait(for: [exp], timeout: 1.0)
+            wait(for: [exp], timeout: timeout)
         }
 
         fpc.move(to: .hidden, animated: true)
@@ -223,6 +225,7 @@ class ControllerTests: XCTestCase {
     }
 
     func test_moveTo_didMoveDelegate() {
+        let timeout = 3.0
         let delegate = FloatingPanelTestDelegate()
         let fpc = FloatingPanelController(delegate: delegate)
         XCTAssertEqual(delegate.position, .hidden)
@@ -237,7 +240,7 @@ class ControllerTests: XCTestCase {
                 exp.fulfill()
             }
             fpc.move(to: .full, animated: false)
-            wait(for: [exp], timeout: 1.0)
+            wait(for: [exp], timeout: timeout)
 
             XCTAssertEqual(count, 1)
         }
@@ -253,7 +256,7 @@ class ControllerTests: XCTestCase {
             fpc.move(to: .half, animated: true) {
                 exp.fulfill()
             }
-            wait(for: [exp], timeout: 1.0)
+            wait(for: [exp], timeout: timeout)
 
             XCTAssertGreaterThan(count, 1)
         }
@@ -270,7 +273,7 @@ class ControllerTests: XCTestCase {
                     exp.fulfill()
                 }
             }
-            wait(for: [exp], timeout: 1.0)
+            wait(for: [exp], timeout: timeout)
 
             XCTAssertEqual(count, 1)
         }
@@ -288,7 +291,7 @@ class ControllerTests: XCTestCase {
                     exp.fulfill()
                 }
             }
-            wait(for: [exp], timeout: 1.0)
+            wait(for: [exp], timeout: timeout)
 
             XCTAssertGreaterThan(count, 1)
         }

Tests/CoreTests.swift

@@ -209,6 +209,8 @@ class CoreTests: XCTestCase {
             return floor(fpc.backdropView.alpha * 1e+06) / 1e+06
         }
 
+        let timeout = 3.0
+
         let delegate = TestDelegate()
         let fpc = FloatingPanelController(delegate: delegate)
         fpc.layout = BackdropTestLayout()
@@ -228,14 +230,14 @@ class CoreTests: XCTestCase {
         fpc.move(to: .full, animated: true) {
             exp1.fulfill()
         }
-        wait(for: [exp1], timeout: 1.0)
+        wait(for: [exp1], timeout: timeout)
         XCTAssertEqual(_floor(fpc.backdropView.alpha), 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)
+        wait(for: [exp2], timeout: timeout)
         XCTAssertEqual(fpc.backdropView.alpha, 0.0)
 
         // Test a content mode change of FloatingPanelController
@@ -246,7 +248,7 @@ class CoreTests: XCTestCase {
         }
         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)
+        wait(for: [exp3], timeout: timeout)
         XCTAssertEqual(_floor(fpc.backdropView.alpha), 0.3)
 
         // Test a size class change of FloatingPanelController.view
@@ -922,7 +924,6 @@ class CoreTests: XCTestCase {
             }
         }
         let fpc = FloatingPanelController()
-        let scrollView = UIScrollView()
         let delegate = Delegate()
         fpc.showForTest()
         fpc.delegate = delegate