fix for swipe to reply on iOS 26 and also improved iOS 18 behaviour

ElementX/Sources/Screens/RoomScreen/View/SwipeRightAction.swift

@@ -28,10 +28,7 @@ struct SwipeRightAction<Label: View>: ViewModifier {
     let action: () -> Void
     
     func body(content: Content) -> some View {
-        content
-            .offset(x: xOffset, y: 0.0)
-            .animation(.interactiveSpring().speed(0.5), value: xOffset)
-            .timelineGesture(gesture)
+        mainContent(content: content)
             .onChange(of: dragGestureActive) { _, newValue in
                 if newValue == true {
                     if shouldStartAction() {
@@ -51,7 +48,65 @@ struct SwipeRightAction<Label: View>: ViewModifier {
             }
     }
     
-    private var gesture: some Gesture {
+    @ViewBuilder
+    private func mainContent(content: Content) -> some View {
+        if #available(iOS 18, *) {
+            content
+                .offset(x: xOffset, y: 0.0)
+                .animation(.interactiveSpring().speed(0.5), value: xOffset)
+                .gesture(PanGesture { gesture in
+                    switch gesture.state {
+                    case .ended, .cancelled, .failed:
+                        if xOffset > actionThreshold {
+                            action()
+                        }
+                        
+                        xOffset = 0.0
+                    default:
+                        guard shouldStartAction() else {
+                            return
+                        }
+                        let translation = gesture.translation(in: nil)
+                        
+                        // Due to https://forums.developer.apple.com/forums/thread/760035 we had to make
+                        // the drag a simultaneous gesture otherwise it was impossible to scroll the timeline.
+                        // Therefore we need to prevent the animation to run if the user is to scrolling vertically.
+                        // It would be nice if we could somehow abort the gesture in this case.
+                        let width: CGFloat = if translation.x > abs(translation.y) {
+                            translation.x
+                        } else {
+                            0.0
+                        }
+                        
+                        // We want to add a spring like behaviour to the drag in which the view
+                        // moves slower the more it's dragged. We use a circular easing function
+                        // to generate those values up to the `swipeThreshold`
+                        // The final translation will be between 0 and `swipeThreshold` with the action being enabled from
+                        // `actionThreshold` onwards
+                        let screenWidthNormalisedTranslation = max(0.0, min(width, swipeThreshold)) / swipeThreshold
+                        let easedTranslation = circularEaseOut(screenWidthNormalisedTranslation)
+                        xOffset = easedTranslation * xOffsetThreshold
+                        
+                        if xOffset > actionThreshold {
+                            if !hasReachedActionThreshold {
+                                feedbackGenerator.impactOccurred()
+                                hasReachedActionThreshold = true
+                            }
+                        } else {
+                            hasReachedActionThreshold = false
+                        }
+                        
+                    }
+                })
+        } else {
+            content
+                .offset(x: xOffset, y: 0.0)
+                .animation(.interactiveSpring().speed(0.5), value: xOffset)
+                .gesture(oldGesture)
+        }
+    }
+    
+    private var oldGesture: some Gesture {
         DragGesture()
             .updating($dragGestureActive) { _, state, _ in
                 // Available actions should be computed on the fly so we use a gesture state change
@@ -113,18 +168,6 @@ extension View {
                           action: @escaping () -> Void) -> some View {
         modifier(SwipeRightAction(label: label, shouldStartAction: shouldStartAction, action: action))
     }
-    
-    @ViewBuilder
-    fileprivate func timelineGesture(_ gesture: some Gesture) -> some View {
-        if #available(iOS 18.0, *) {
-            // iOS 18 has a bug https://forums.developer.apple.com/forums/thread/760035 and you
-            // can't scroll the timeline when `gesture` is used.
-            simultaneousGesture(gesture)
-        } else {
-            // Equally on iOS 17 you can't scroll the timeline when `simultaneousGesture` is used.
-            self.gesture(gesture)
-        }
-    }
 }
 
 struct SwipeRightAction_Previews: PreviewProvider, TestablePreview {
@@ -159,3 +202,38 @@ struct SwipeRightAction_Previews: PreviewProvider, TestablePreview {
         }
     }
 }
+
+// Fixes the issue on iOS 18 where DragGesture conflicts with the scroll view
+// https://github.com/feedback-assistant/reports/issues/542#issuecomment-2581322968
+private struct PanGesture: UIGestureRecognizerRepresentable {
+    var handle: (UIPanGestureRecognizer) -> Void
+    
+    func makeCoordinator(converter: CoordinateSpaceConverter) -> Coordinator { .init() }
+    
+    func makeUIGestureRecognizer(context: Context) -> UIPanGestureRecognizer {
+        let gesture = UIPanGestureRecognizer()
+        gesture.delegate = context.coordinator
+        gesture.isEnabled = true
+        return gesture
+    }
+    
+    func handleUIGestureRecognizerAction(_ recognizer: UIPanGestureRecognizer, context: Context) {
+        handle(recognizer)
+    }
+    
+    class Coordinator: NSObject, UIGestureRecognizerDelegate {
+        func gestureRecognizer(
+            _ gestureRecognizer: UIGestureRecognizer,
+            shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer
+        ) -> Bool {
+            false
+        }
+        
+        func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
+            guard let panRecognizer = gestureRecognizer as? UIPanGestureRecognizer else { return false }
+
+            let velocity = panRecognizer.velocity(in: gestureRecognizer.view)
+            return abs(velocity.y) < abs(velocity.x)
+        }
+    }
+}