Add Duckable package, make Compose screen duckable

Packages/Duckable/.gitignore

@@ -0,0 +1,9 @@
+.DS_Store
+/.build
+/Packages
+/*.xcodeproj
+xcuserdata/
+DerivedData/
+.swiftpm/config/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc

Packages/Duckable/Package.swift

@@ -0,0 +1,31 @@
+// swift-tools-version: 5.7
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "Duckable",
+    platforms: [
+        .iOS(.v15),
+    ],
+    products: [
+        // Products define the executables and libraries a package produces, and make them visible to other packages.
+        .library(
+            name: "Duckable",
+            targets: ["Duckable"]),
+    ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        // .package(url: /* package url */, from: "1.0.0"),
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages this package depends on.
+        .target(
+            name: "Duckable",
+            dependencies: []),
+        .testTarget(
+            name: "DuckableTests",
+            dependencies: ["Duckable"]),
+    ]
+)

Packages/Duckable/README.md

@@ -0,0 +1,3 @@
+# Duckable
+
+A package that allows modally-presented view controllers to be 'ducked' to make the content behind them accessible (à la Mail.app).

Packages/Duckable/Sources/Duckable/API.swift

@@ -0,0 +1,44 @@
+//
+//  API.swift
+//  Duckable
+//
+//  Created by Shadowfacts on 11/7/22.
+//
+
+import UIKit
+
+public protocol DuckableViewController: UIViewController {
+    var duckableDelegate: DuckableViewControllerDelegate? { get set }
+    
+    func duckableViewControllerMayAttemptToDuck()
+    
+    func duckableViewControllerWillAnimateDuck(withDuration duration: CGFloat, afterDelay delay: CGFloat)
+    
+    func duckableViewControllerDidFinishAnimatingDuck()
+}
+
+extension DuckableViewController {
+    public func duckableViewControllerMayAttemptToDuck() {}
+    public func duckableViewControllerWillAnimateDuck(withDuration duration: CGFloat, afterDelay delay: CGFloat) {}
+    public func duckableViewControllerDidFinishAnimatingDuck() {}
+}
+
+public protocol DuckableViewControllerDelegate: AnyObject {
+    func duckableViewControllerWillDismiss(animated: Bool)
+}
+
+extension UIViewController {
+    @available(iOS 16.0, *)
+    public func presentDuckable(_ viewController: DuckableViewController) -> Bool {
+        var cur: UIViewController? = self
+        while let vc = cur {
+            if let container = vc as? DuckableContainerViewController {
+                container.presentDuckable(viewController, animated: true, completion: nil)
+                return true
+            } else {
+                cur = vc.parent
+            }
+        }
+        return false
+    }
+}

Packages/Duckable/Sources/Duckable/DetentIdentifier.swift

@@ -0,0 +1,12 @@
+//
+//  DetentIdentifier.swift
+//  Duckable
+//
+//  Created by Shadowfacts on 11/7/22.
+//
+
+import UIKit
+
+extension UISheetPresentationController.Detent.Identifier {
+    static let bottom = Self("\(Bundle.main.bundleIdentifier!).bottom")
+}

Packages/Duckable/Sources/Duckable/DuckAnimationController.swift

@@ -0,0 +1,89 @@
+//
+//  DuckAnimationController.swift
+//  Duckable
+//
+//  Created by Shadowfacts on 11/7/22.
+//
+
+import UIKit
+
+@available(iOS 16.0, *)
+class DuckAnimationController: NSObject, UIViewControllerAnimatedTransitioning {
+    let owner: DuckableContainerViewController
+    let needsShrinkAnimation: Bool
+    
+    init(owner: DuckableContainerViewController, needsShrinkAnimation: Bool) {
+        self.owner = owner
+        self.needsShrinkAnimation = needsShrinkAnimation
+    }
+    
+    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
+        return 0.2
+    }
+
+    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
+        guard case .ducked(let duckable, placeholder: let placeholder) = owner.state,
+              let presented = transitionContext.viewController(forKey: .from) else {
+            transitionContext.completeTransition(false)
+            return
+        }
+
+        guard transitionContext.isAnimated else {
+            transitionContext.completeTransition(true)
+            return
+        }
+        
+        let container = transitionContext.containerView
+        
+
+        if needsShrinkAnimation {
+            
+            duckable.duckableViewControllerWillAnimateDuck(withDuration: 0.2, afterDelay: 0.2)
+
+            let presentedFrameInContainer = container.convert(presented.view.bounds, from: presented.view)
+            let heightToSlide = container.bounds.height - container.safeAreaInsets.bottom - detentHeight - presentedFrameInContainer.minY
+
+            let slideAnimator = UIViewPropertyAnimator(duration: 0.4, dampingRatio: 1)
+            slideAnimator.addAnimations {
+                container.transform = CGAffineTransform(translationX: 0, y: heightToSlide + 10)
+            }
+            slideAnimator.addCompletion { _ in
+                duckable.duckableViewControllerDidFinishAnimatingDuck()
+                transitionContext.completeTransition(true)
+            }
+            slideAnimator.startAnimation()
+
+            placeholder.view.transform = CGAffineTransform(translationX: 0, y: 10)
+            let bounceAnimator = UIViewPropertyAnimator(duration: 0.1, curve: .linear) {
+                placeholder.view.transform = .identity
+                container.transform = CGAffineTransform(translationX: 0, y: heightToSlide)
+            }
+            bounceAnimator.startAnimation(afterDelay: 0.3)
+
+            let fadeAnimator = UIViewPropertyAnimator(duration: 0.1, curve: .linear) {
+                presented.view.layer.opacity = 0
+            }
+            fadeAnimator.startAnimation(afterDelay: 0.3)
+
+        } else {
+            
+            duckable.duckableViewControllerWillAnimateDuck(withDuration: 0.2, afterDelay: 0)
+
+            placeholder.view.transform = CGAffineTransform(translationX: 0, y: 10)
+            let bounceAnimator = UIViewPropertyAnimator(duration: 0.1, curve: .linear) {
+                placeholder.view.transform = .identity
+                container.transform = CGAffineTransform(translationX: 0, y: -10)
+            }
+            bounceAnimator.startAnimation(afterDelay: 0.2)
+
+            let fadeAnimator = UIViewPropertyAnimator(duration: 0.1, curve: .linear) {
+                presented.view.layer.opacity = 0
+            }
+            fadeAnimator.addCompletion { _ in
+                duckable.duckableViewControllerDidFinishAnimatingDuck()
+                transitionContext.completeTransition(true)
+            }
+            fadeAnimator.startAnimation(afterDelay: 0.2)
+        }
+    }
+}

Packages/Duckable/Sources/Duckable/DuckableContainerViewController.swift

@@ -0,0 +1,217 @@
+//
+//  DuckableContainerViewController.swift
+//  Duckable
+//
+//  Created by Shadowfacts on 11/7/22.
+//
+
+import UIKit
+
+let duckedCornerRadius: CGFloat = 10
+let detentHeight: CGFloat = 44
+
+@available(iOS 16.0, *)
+public class DuckableContainerViewController: UIViewController, DuckableViewControllerDelegate {
+    
+    public let child: UIViewController
+    private var bottomConstraint: NSLayoutConstraint!
+    private(set) var state = State.idle
+    
+    public init(child: UIViewController) {
+        self.child = child
+        
+        super.init(nibName: nil, bundle: nil)
+        
+        swizzleSheetController()
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError()
+    }
+
+    public override func viewDidLoad() {
+        super.viewDidLoad()
+        
+        view.backgroundColor = .black
+
+        child.beginAppearanceTransition(true, animated: false)
+        addChild(child)
+        child.didMove(toParent: self)
+        child.view.translatesAutoresizingMaskIntoConstraints = false
+        view.addSubview(child.view)
+        child.endAppearanceTransition()
+        
+        bottomConstraint = child.view.bottomAnchor.constraint(equalTo: view.bottomAnchor)
+        NSLayoutConstraint.activate([
+            child.view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            child.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+            child.view.topAnchor.constraint(equalTo: view.topAnchor),
+            bottomConstraint,
+        ])
+    }
+    
+    func presentDuckable(_ viewController: DuckableViewController, animated: Bool, completion: (() -> Void)?) {
+        guard case .idle = state else {
+            if animated,
+               case .ducked(_, placeholder: let placeholder) = state {
+                UIImpactFeedbackGenerator(style: .soft).impactOccurred()
+                let origConstant = placeholder.topConstraint.constant
+                UIView.animateKeyframes(withDuration: 0.4, delay: 0) {
+                    UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 0.5) {
+                        placeholder.topConstraint.constant = origConstant - 20
+                        self.view.layoutIfNeeded()
+                    }
+                    UIView.addKeyframe(withRelativeStartTime: 0.5, relativeDuration: 0.5) {
+                        placeholder.topConstraint.constant = origConstant
+                        self.view.layoutIfNeeded()
+                    }
+                }
+            }
+            return
+        }
+        state = .presentingDucked(viewController, isFirstPresentation: true)
+        doPresentDuckable(viewController, animated: animated, completion: completion)
+    }
+    
+    private func doPresentDuckable(_ viewController: DuckableViewController, animated: Bool, completion: (() -> Void)?) {
+        viewController.duckableDelegate = self
+        let nav = UINavigationController(rootViewController: viewController)
+        nav.modalPresentationStyle = .custom
+        nav.transitioningDelegate = self
+        present(nav, animated: animated) {
+            self.bottomConstraint.isActive = false
+            self.bottomConstraint = self.child.view.bottomAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.bottomAnchor, constant: -detentHeight - 4)
+            self.bottomConstraint.isActive = true
+            completion?()
+        }
+    }
+    
+    public func duckableViewControllerWillDismiss(animated: Bool) {
+        state = .idle
+        bottomConstraint.isActive = false
+        bottomConstraint = child.view.bottomAnchor.constraint(equalTo: view.bottomAnchor)
+        bottomConstraint.isActive = true
+        child.view.layer.cornerRadius = 0
+        setOverrideTraitCollection(nil, forChild: child)
+    }
+    
+    func createPlaceholderForDuckedViewController(_ viewController: DuckableViewController) -> DuckedPlaceholderViewController {
+        let placeholder = DuckedPlaceholderViewController(for: viewController, owner: self)
+        placeholder.view.translatesAutoresizingMaskIntoConstraints = false
+        
+        placeholder.beginAppearanceTransition(true, animated: false)
+        self.addChild(placeholder)
+        placeholder.didMove(toParent: self)
+        self.view.addSubview(placeholder.view)
+        placeholder.endAppearanceTransition()
+        
+        let placeholderTopConstraint = placeholder.view.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.bottomAnchor, constant: -detentHeight)
+        placeholder.topConstraint = placeholderTopConstraint
+        NSLayoutConstraint.activate([
+            placeholder.view.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
+            placeholder.view.trailingAnchor.constraint(equalTo: self.view.trailingAnchor),
+            placeholder.view.bottomAnchor.constraint(equalTo: self.view.bottomAnchor),
+            placeholderTopConstraint
+        ])
+            
+        // otherwise the layout changes get lumped in with the system animation
+        UIView.performWithoutAnimation {
+            self.view.layoutIfNeeded()
+        }
+        return placeholder
+    }
+    
+    func duckViewController() {
+        guard case .presentingDucked(let viewController, isFirstPresentation: _) = state else {
+            return
+        }
+        let placeholder = createPlaceholderForDuckedViewController(viewController)
+        state = .ducked(viewController, placeholder: placeholder)
+        child.view.layer.cornerRadius = duckedCornerRadius
+        child.view.layer.maskedCorners = [.layerMinXMaxYCorner, .layerMaxXMaxYCorner]
+        child.view.layer.masksToBounds = true
+        dismiss(animated: true)
+    }
+    
+    @objc func unduckViewController() {
+        guard case .ducked(let viewController, placeholder: let placeholder) = state else {
+            return
+        }
+        state = .presentingDucked(viewController, isFirstPresentation: false)
+        doPresentDuckable(viewController, animated: true) {
+            placeholder.view.removeFromSuperview()
+            placeholder.willMove(toParent: nil)
+            placeholder.removeFromParent()
+        }
+    }
+    
+    func sheetOffsetDidChange() {
+        if case .presentingDucked(let duckable, isFirstPresentation: _) = state {
+            duckable.duckableViewControllerMayAttemptToDuck()
+        }
+    }
+    
+    enum State {
+        case idle
+        case presentingDucked(DuckableViewController, isFirstPresentation: Bool)
+        case ducked(DuckableViewController, placeholder: DuckedPlaceholderViewController)
+    }
+
+}
+
+@available(iOS 16.0, *)
+extension DuckableContainerViewController: UIViewControllerTransitioningDelegate {
+    public func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
+        let controller = UISheetPresentationController(presentedViewController: presented, presenting: presenting)
+        controller.delegate = self
+        controller.prefersGrabberVisible = true
+        controller.selectedDetentIdentifier = .large
+        controller.largestUndimmedDetentIdentifier = .bottom
+        controller.detents = [
+            .custom(identifier: .bottom, resolver: { context in
+                return detentHeight
+            }),
+            .large(),
+        ]
+        return controller
+    }
+    
+    public func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
+        if case .ducked(_, placeholder: _) = state {
+            return DuckAnimationController(
+                owner: self,
+                needsShrinkAnimation: isDetentChangingDueToGrabberAction
+            )
+        } else {
+            return nil
+        }
+    }
+}
+
+@available(iOS 16.0, *)
+extension DuckableContainerViewController: UISheetPresentationControllerDelegate {
+    public func presentationController(_ presentationController: UIPresentationController, willPresentWithAdaptiveStyle style: UIModalPresentationStyle, transitionCoordinator: UIViewControllerTransitionCoordinator?) {
+        let snapshot = child.view.snapshotView(afterScreenUpdates: false)!
+        snapshot.translatesAutoresizingMaskIntoConstraints = false
+        self.view.addSubview(snapshot)
+        NSLayoutConstraint.activate([
+            snapshot.leadingAnchor.constraint(equalTo: child.view.leadingAnchor),
+            snapshot.trailingAnchor.constraint(equalTo: child.view.trailingAnchor),
+            snapshot.topAnchor.constraint(equalTo: child.view.topAnchor),
+            snapshot.bottomAnchor.constraint(equalTo: child.view.bottomAnchor),
+        ])
+        setOverrideTraitCollection(UITraitCollection(userInterfaceLevel: .elevated), forChild: child)
+        transitionCoordinator!.animate { context in
+            snapshot.layer.opacity = 0
+        } completion: { _ in
+            snapshot.removeFromSuperview()
+        }
+    }
+    
+    public func sheetPresentationControllerDidChangeSelectedDetentIdentifier(_ sheetPresentationController: UISheetPresentationController) {
+        if sheetPresentationController.selectedDetentIdentifier == .bottom {
+            duckViewController()
+        }
+    }
+}
+

Packages/Duckable/Sources/Duckable/DuckedPlaceholderViewController.swift

@@ -0,0 +1,71 @@
+//
+//  DuckedPlaceholderView.swift
+//  Duckable
+//
+//  Created by Shadowfacts on 11/7/22.
+//
+
+import UIKit
+
+@available(iOS 16.0, *)
+class DuckedPlaceholderViewController: UIViewController {
+    private unowned let owner: DuckableContainerViewController
+    private let navBar = UINavigationBar()
+    
+    var topConstraint: NSLayoutConstraint!
+    
+    init(for duckableViewController: DuckableViewController, owner: DuckableContainerViewController) {
+        self.owner = owner
+        
+        super.init(nibName: nil, bundle: nil)
+        
+        let item = UINavigationItem()
+        item.title = duckableViewController.navigationItem.title
+        item.titleView = duckableViewController.navigationItem.titleView
+        navBar.setItems([item], animated: false)
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError()
+    }
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        
+        setBackgroundColor()
+        view.layer.cornerRadius = duckedCornerRadius
+        view.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
+        view.layer.shadowColor = UIColor.black.cgColor
+        view.layer.shadowOpacity = 0.05
+        
+        view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(placeholderTapped)))
+        
+        let appearance = UINavigationBarAppearance()
+        appearance.configureWithTransparentBackground()
+        navBar.standardAppearance = appearance
+        navBar.isUserInteractionEnabled = false
+        navBar.translatesAutoresizingMaskIntoConstraints = false
+        view.addSubview(navBar)
+        NSLayoutConstraint.activate([
+            navBar.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            navBar.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+            navBar.topAnchor.constraint(equalTo: view.topAnchor),
+        ])
+    }
+    
+    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
+        super.traitCollectionDidChange(previousTraitCollection)
+        
+        setBackgroundColor()
+    }
+    
+    private func setBackgroundColor() {
+        // when just using .systemBackground and setting the override trait collection for the placeholder VC,
+        // the color doesn't change until after the dismiss animation occurs (but only when tapping the grabber to duck, not when swiping)
+        view.backgroundColor = .systemBackground.resolvedColor(with: UITraitCollection(traitsFrom: [traitCollection, UITraitCollection(userInterfaceLevel: .elevated)]))
+    }
+    
+    @objc private func placeholderTapped() {
+        owner.unduckViewController()
+    }
+}

Packages/Duckable/Sources/Duckable/Swizzler.swift

@@ -0,0 +1,33 @@
+//
+//  Swizzler.swift
+//  Duckable
+//
+//  Created by Shadowfacts on 11/7/22.
+//
+
+import UIKit
+import os.log
+
+private var hasInitialized = false
+var isDetentChangingDueToGrabberAction = false
+
+@available(iOS 16.0, *)
+func swizzleSheetController() {
+    guard !hasInitialized else {
+        return
+    }
+    hasInitialized = true
+    
+    var originalIMP: IMP?
+    let imp = imp_implementationWithBlock({ (self: UISheetPresentationController, param: AnyObject) in
+        let original = unsafeBitCast(originalIMP!, to: (@convention(c) (UISheetPresentationController, AnyObject) -> Void).self)
+        isDetentChangingDueToGrabberAction = true
+        original(self, param)
+        isDetentChangingDueToGrabberAction = false
+    } as @convention(block) (UISheetPresentationController, AnyObject) -> Void)
+    let sel = [":", "PrimaryAction", "GrabberDidTrigger", "dropShadowView", "_"].reversed().joined()
+    originalIMP = class_replaceMethod(UISheetPresentationController.self, Selector(sel), imp, "v@:@")
+    if originalIMP == nil {
+        os_log(.fault, log: .default, "Unable to initialize Duckable grabber tap hook")
+    }
+}

Tusker.xcodeproj/project.pbxproj

@@ -255,6 +255,8 @@
 		D6BC9DB5232D4CE3002CA326 /* NotificationsMode.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6BC9DB4232D4CE3002CA326 /* NotificationsMode.swift */; };
 		D6BC9DD7232D7811002CA326 /* TimelinesPageViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6BC9DD6232D7811002CA326 /* TimelinesPageViewController.swift */; };
 		D6BC9DDA232D8BE5002CA326 /* SearchResultsViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6BC9DD9232D8BE5002CA326 /* SearchResultsViewController.swift */; };
+		D6BEA245291A0EDE002F4D01 /* Duckable in Frameworks */ = {isa = PBXBuildFile; productRef = D6BEA244291A0EDE002F4D01 /* Duckable */; };
+		D6BEA247291A0F2D002F4D01 /* Duckable+Root.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6BEA246291A0F2D002F4D01 /* Duckable+Root.swift */; };
 		D6BED174212667E900F02DA0 /* TimelineStatusTableViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6BED173212667E900F02DA0 /* TimelineStatusTableViewCell.swift */; };
 		D6C143DA253510F4007DC240 /* ComposeEmojiTextField.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6C143D9253510F4007DC240 /* ComposeEmojiTextField.swift */; };
 		D6C1B2082545D1EC00DAAA66 /* StatusCardView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6C1B2072545D1EC00DAAA66 /* StatusCardView.swift */; };
@@ -611,6 +613,8 @@
 		D6BC9DB4232D4CE3002CA326 /* NotificationsMode.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NotificationsMode.swift; sourceTree = "<group>"; };
 		D6BC9DD6232D7811002CA326 /* TimelinesPageViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelinesPageViewController.swift; sourceTree = "<group>"; };
 		D6BC9DD9232D8BE5002CA326 /* SearchResultsViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SearchResultsViewController.swift; sourceTree = "<group>"; };
+		D6BEA243291A0C83002F4D01 /* Duckable */ = {isa = PBXFileReference; lastKnownFileType = wrapper; name = Duckable; path = Packages/Duckable; sourceTree = "<group>"; };
+		D6BEA246291A0F2D002F4D01 /* Duckable+Root.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Duckable+Root.swift"; sourceTree = "<group>"; };
 		D6BED173212667E900F02DA0 /* TimelineStatusTableViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineStatusTableViewCell.swift; sourceTree = "<group>"; };
 		D6C143D9253510F4007DC240 /* ComposeEmojiTextField.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposeEmojiTextField.swift; sourceTree = "<group>"; };
 		D6C1B2072545D1EC00DAAA66 /* StatusCardView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StatusCardView.swift; sourceTree = "<group>"; };
@@ -689,6 +693,7 @@
 				D6552367289870790048A653 /* ScreenCorners in Frameworks */,
 				D6676CA527A8D0020052936B /* WebURLFoundationExtras in Frameworks */,
 				D63CC702290EC0B8000E19DE /* Sentry in Frameworks */,
+				D6BEA245291A0EDE002F4D01 /* Duckable in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -935,6 +940,7 @@
 			isa = PBXGroup;
 			children = (
 				D6FF985F255C717400845181 /* AccountSwitchingContainerViewController.swift */,
+				D6BEA246291A0F2D002F4D01 /* Duckable+Root.swift */,
 				D6F0B12A24A3071C001E48C3 /* MainSplitViewController.swift */,
 				04DACE8B212CB14B009840C4 /* MainTabBarViewController.swift */,
 				D6F0B17424A3A1AA001E48C3 /* MainSidebarViewController.swift */,
@@ -1362,6 +1368,7 @@
 			children = (
 				D63CC703290EC472000E19DE /* Dist.xcconfig */,
 				D674A50727F910F300BA03AC /* Pachyderm */,
+				D6BEA243291A0C83002F4D01 /* Duckable */,
 				D6D4DDCE212518A000E1C4BB /* Tusker */,
 				D6D4DDE3212518A200E1C4BB /* TuskerTests */,
 				D6D4DDEE212518A200E1C4BB /* TuskerUITests */,
@@ -1528,6 +1535,7 @@
 				D674A50827F9128D00BA03AC /* Pachyderm */,
 				D6552366289870790048A653 /* ScreenCorners */,
 				D63CC701290EC0B8000E19DE /* Sentry */,
+				D6BEA244291A0EDE002F4D01 /* Duckable */,
 			);
 			productName = Tusker;
 			productReference = D6D4DDCC212518A000E1C4BB /* Tusker.app */;
@@ -1990,6 +1998,7 @@
 				D6895DC428D65342006341DA /* ConfirmReblogStatusPreviewView.swift in Sources */,
 				D67895BC24671E6D00D4CD9E /* PKDrawing+Render.swift in Sources */,
 				D62E9987279D094F00C26176 /* StatusMetaIndicatorsView.swift in Sources */,
+				D6BEA247291A0F2D002F4D01 /* Duckable+Root.swift in Sources */,
 				04D14BB022B34A2800642648 /* GalleryViewController.swift in Sources */,
 				D6C1B2082545D1EC00DAAA66 /* StatusCardView.swift in Sources */,
 				D64BC18A23C16487000D0238 /* UnpinStatusActivity.swift in Sources */,
@@ -2693,6 +2702,10 @@
 			isa = XCSwiftPackageProductDependency;
 			productName = Pachyderm;
 		};
+		D6BEA244291A0EDE002F4D01 /* Duckable */ = {
+			isa = XCSwiftPackageProductDependency;
+			productName = Duckable;
+		};
 /* End XCSwiftPackageProductDependency section */
 
 /* Begin XCVersionGroup section */

Tusker/Scenes/MainSceneDelegate.swift

@@ -10,6 +10,7 @@ import UIKit
 import Pachyderm
 import MessageUI
 import CoreData
+import Duckable
 
 class MainSceneDelegate: UIResponder, UIWindowSceneDelegate, TuskerSceneDelegate {
     
@@ -205,7 +206,14 @@ class MainSceneDelegate: UIResponder, UIWindowSceneDelegate, TuskerSceneDelegate
         mastodonController.getOwnAccount()
         mastodonController.getOwnInstance()
         
-        return MainSplitViewController(mastodonController: mastodonController)
+        let split = MainSplitViewController(mastodonController: mastodonController)
+        if UIDevice.current.userInterfaceIdiom == .phone,
+           #available(iOS 16.0, *) {
+            // TODO: maybe the duckable container should be outside the account switching container
+            return DuckableContainerViewController(child: split)
+        } else {
+            return split
+        }
     }
     
     func createOnboardingUI() -> UIViewController {

Tusker/Screens/Compose/ComposeHostingController.swift

@@ -10,14 +10,16 @@ import SwiftUI
 import Combine
 import Pachyderm
 import PencilKit
+import Duckable
 
 protocol ComposeHostingControllerDelegate: AnyObject {
     func dismissCompose(mode: ComposeUIState.DismissMode) -> Bool
 }
 
-class ComposeHostingController: UIHostingController<ComposeContainerView> {
+class ComposeHostingController: UIHostingController<ComposeContainerView>, DuckableViewController {
     
     weak var delegate: ComposeHostingControllerDelegate?
+    weak var duckableDelegate: DuckableViewControllerDelegate?
     
     let mastodonController: MastodonController
     
@@ -103,16 +105,15 @@ class ComposeHostingController: UIHostingController<ComposeContainerView> {
         fatalError("init(coder:) has not been implemented")
     }
     
-    override func didMove(toParent parent: UIViewController?) {
+    override func willMove(toParent parent: UIViewController?) {
-        super.didMove(toParent: parent)
+        super.willMove(toParent: parent)
         
         if let parent = parent {
             parent.view.addSubview(mainToolbar)
             NSLayoutConstraint.activate([
-                mainToolbar.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+                mainToolbar.leadingAnchor.constraint(equalTo: parent.view.leadingAnchor),
-                mainToolbar.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+                mainToolbar.trailingAnchor.constraint(equalTo: parent.view.trailingAnchor),
-                // use the top anchor of the toolbar so our additionalSafeAreaInsets (which has the bottom as the toolbar height) don't affect it
+                mainToolbar.bottomAnchor.constraint(equalTo: parent.view.safeAreaLayoutGuide.bottomAnchor),
-                mainToolbar.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
             ])
         }
     }
@@ -301,6 +302,19 @@ class ComposeHostingController: UIHostingController<ComposeContainerView> {
         }
     }
     
+    // MARK: Duckable
+    
+    func duckableViewControllerWillAnimateDuck(withDuration duration: CGFloat, afterDelay delay: CGFloat) {
+        let animator = UIViewPropertyAnimator(duration: duration, curve: .linear) {
+            self.mainToolbar.layer.opacity = 0
+        }
+        animator.startAnimation(afterDelay: delay)
+    }
+    
+    func duckableViewControllerDidFinishAnimatingDuck() {
+        mainToolbar.layer.opacity = 1
+    }
+    
     // MARK: Interaction
     
     @objc func cwButtonPressed() {
@@ -335,6 +349,7 @@ extension ComposeHostingController: ComposeUIStateDelegate {
         let dismissed = delegate?.dismissCompose(mode: mode) ?? false
         if !dismissed {
             self.dismiss(animated: true)
+            self.duckableDelegate?.duckableViewControllerWillDismiss(animated: true)
         }
     }
     
@@ -424,6 +439,8 @@ extension ComposeHostingController: DraftsTableViewControllerDelegate {
     }
 }
 
+// superseded by duckable stuff
+@available(iOS, obsoleted: 16.0)
 extension ComposeHostingController: UIAdaptivePresentationControllerDelegate {
     func presentationControllerShouldDismiss(_ presentationController: UIPresentationController) -> Bool {
         return Preferences.shared.automaticallySaveDrafts || !draft.hasContent

Tusker/Screens/Compose/ComposeView.swift

@@ -97,7 +97,7 @@ struct ComposeView: View {
                     globalFrameOutsideList = frame
                 }
         })
-        .navigationBarTitle("Compose")
+        .navigationTitle(navTitle)
         .actionSheet(isPresented: $uiState.isShowingSaveDraftSheet, content: self.saveAndCloseSheet)
         .alert(isPresented: $isShowingPostErrorAlert) {
             Alert(
@@ -180,6 +180,15 @@ struct ComposeView: View {
         }.frame(height: 50)
     }
     
+    private var navTitle: Text {
+        if let id = draft.inReplyToID,
+           let status = mastodonController.persistentContainer.status(for: id) {
+            return Text("Reply to @\(status.account.acct)")
+        } else {
+            return Text("New Post")
+        }
+    }
+    
     private var cancelButton: some View {
         Button(action: self.cancel) {
             Text("Cancel")

Tusker/Screens/Main/Duckable+Root.swift

@@ -0,0 +1,37 @@
+//
+//  Duckable+Root.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 11/7/22.
+//  Copyright © 2022 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+import Duckable
+
+@available(iOS 16.0, *)
+extension DuckableContainerViewController: TuskerRootViewController {
+    func presentCompose() {
+        (child as? TuskerRootViewController)?.presentCompose()
+    }
+    
+    func select(tab: MainTabBarViewController.Tab) {
+        (child as? TuskerRootViewController)?.select(tab: tab)
+    }
+    
+    func getTabController(tab: MainTabBarViewController.Tab) -> UIViewController? {
+        return (child as? TuskerRootViewController)?.getTabController(tab: tab)
+    }
+    
+    func performSearch(query: String) {
+        (child as? TuskerRootViewController)?.performSearch(query: query)
+    }
+    
+    func presentPreferences(completion: (() -> Void)?) {
+        (child as? TuskerRootViewController)?.presentPreferences(completion: completion)
+    }
+    
+    func handleStatusBarTapped(xPosition: CGFloat) -> StatusBarTapActionResult {
+        (child as? TuskerRootViewController)?.handleStatusBarTapped(xPosition: xPosition) ?? .continue
+    }
+}

Tusker/Screens/Main/MainSplitViewController.swift

@@ -373,19 +373,13 @@ fileprivate extension MainSidebarViewController.Item {
     }
 }
 
+extension MainSplitViewController: TuskerNavigationDelegate {
+    var apiController: MastodonController! { mastodonController }
+}
+
 extension MainSplitViewController: TuskerRootViewController {
     @objc func presentCompose() {
-        if UIDevice.current.userInterfaceIdiom == .pad || UIDevice.current.userInterfaceIdiom == .mac {
+        self.compose()
-            let compose = UserActivityManager.newPostActivity(mentioning: nil, accountID: mastodonController.accountInfo!.id)
-            let options = UIWindowScene.ActivationRequestOptions()
-            options.preferredPresentationStyle = .prominent
-            UIApplication.shared.requestSceneSessionActivation(nil, userActivity: compose, options: options, errorHandler: nil)
-        } else {
-            let vc = ComposeHostingController(mastodonController: mastodonController)
-            let nav = EnhancedNavigationViewController(rootViewController: vc)
-            nav.presentationController?.delegate = vc
-            present(nav, animated: true)
-        }
     }
     
     func select(tab: MainTabBarViewController.Tab) {

Tusker/Screens/Main/MainTabBarViewController.swift

@@ -228,19 +228,13 @@ extension MainTabBarViewController: FastAccountSwitcherViewControllerDelegate {
     }
 }
 
+extension MainTabBarViewController: TuskerNavigationDelegate {
+    var apiController: MastodonController! { mastodonController }
+}
+
 extension MainTabBarViewController: TuskerRootViewController {
     @objc func presentCompose() {
-        if UIDevice.current.userInterfaceIdiom == .pad || UIDevice.current.userInterfaceIdiom == .mac {
+        compose()
-            let compose = UserActivityManager.newPostActivity(mentioning: nil, accountID: mastodonController.accountInfo!.id)
-            let options = UIWindowScene.ActivationRequestOptions()
-            options.preferredPresentationStyle = .prominent
-            UIApplication.shared.requestSceneSessionActivation(nil, userActivity: compose, options: options, errorHandler: nil)
-        } else {
-            let vc = ComposeHostingController(mastodonController: mastodonController)
-            let nav = EnhancedNavigationViewController(rootViewController: vc)
-            nav.presentationController?.delegate = vc
-            present(nav, animated: true)
-        }
     }
     
     func select(tab: Tab) {

Tusker/TuskerNavigationDelegate.swift

@@ -94,6 +94,11 @@ extension TuskerNavigationDelegate {
             let options = UIWindowScene.ActivationRequestOptions()
             options.preferredPresentationStyle = .prominent
             UIApplication.shared.requestSceneSessionActivation(nil, userActivity: compose, options: options, errorHandler: nil)
+        } else {
+            let compose = ComposeHostingController(draft: draft, mastodonController: apiController)
+            if #available(iOS 16.0, *),
+               presentDuckable(compose) {
+                return
             } else {
                 let compose = ComposeHostingController(draft: draft, mastodonController: apiController)
                 let nav = UINavigationController(rootViewController: compose)
@@ -101,6 +106,7 @@ extension TuskerNavigationDelegate {
                 present(nav, animated: true)
             }
         }
+    }
     
     func compose(inReplyToID: String? = nil, mentioningAcct: String? = nil) {
         let draft = apiController.createDraft(inReplyToID: inReplyToID, mentioningAcct: mentioningAcct)