Fix scrolling in the message list when presented with a sheet on iOS 26

[laevandus]

🔗 Issue Links

Fixes: IOS-1214

🎯 Goal

Scrolling does not work when dragging from a message, but only if message list is shown with a sheet on iOS 26

📝 Summary

• Move simultaneous drag gesture to the ScrollView from the message view
• Propagate dragging state to message items which will handle swipe to reply

🛠 Implementation

iOS 26 changed how simultaneous gestures work:

Fixed: Gestures added using the simultaneousGesture(_:isEnabled:) view modifier are incorrectly simultaneous with ancestor gestures. (147970990)

This breaks scrolling when our drag gesture is used for swiping. Fix is to attach the gesture to the ScrollView directly.

🎨 Showcase

At the end of the before video, scrolling stops working.

Before	After

🧪 Manual Testing Notes

Change the SDK to open channel in a sheet. Quick and dirty change:

diff --git a/DemoAppSwiftUI/DemoAppSwiftUIApp.swift b/DemoAppSwiftUI/DemoAppSwiftUIApp.swift
index 02ffe0dd..784b79b5 100644
--- a/DemoAppSwiftUI/DemoAppSwiftUIApp.swift
+++ b/DemoAppSwiftUI/DemoAppSwiftUIApp.swift
@@ -14,6 +14,7 @@ struct DemoAppSwiftUIApp: App {
 
     @ObservedObject var appState = AppState.shared
     @ObservedObject var notificationsHandler = NotificationsHandler.shared
+    @State private var presentedChannel: ChatChannel?
 
     var channelListController: ChatChannelListController? {
         appState.channelListController
@@ -40,6 +41,9 @@ struct DemoAppSwiftUIApp: App {
                         .badge(appState.unreadCount.threads)
                 }
                 .id(appState.contentIdentifier)
+                .sheet(item: $presentedChannel, content: { channel in
+                    ChatChannelView(channelController: chatClient.channelController(for: channel.cid))
+                })
             }
         }
         .onChange(of: appState.userState) { newValue in
@@ -61,6 +65,9 @@ struct DemoAppSwiftUIApp: App {
             ChatChannelListView(
                 viewFactory: DemoAppFactory.shared,
                 channelListController: channelListController,
+                onItemTap: { channel in
+                    presentedChannel = channel
+                },
                 searchType: channelListSearchType
             )
         }

1. Open a channel with preferably long message
2. Try to swipe to reply and scrolling up and down while dragging from the message bubble. Result: view is scrolled as expected (I found scrolling stopping to work after triggering swipe to reply or just trying a scrolling down and then up. It reproduces pretty quickly)

☑️ Contributor Checklist

• I have signed the Stream CLA (required)
• This change should be manually QAed
• Changelog is updated with client-facing changes
• Changelog is updated with new localization keys
• New code is covered by unit tests
• Documentation has been updated in the docs-content repo

[nuno-vieira]

LGTM! ✅

[martinmitrevski]

We should be careful with this one - it will probably break swiping for custom message container views. Additionally, it should be QA-ed by @testableapple.

[github-actions]

Public Interface

🚀 No changes affecting the public interface.

[sonarqubecloud]

Quality Gate failed

Failed conditions
45.9% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

[Stream-SDK-Bot]

SDK Size

title	develop	branch	diff	status
StreamChatSwiftUI	9.67 MB	9.67 MB	+1 KB	🟢

[Stream-SDK-Bot]

StreamChatSwiftUI XCSize

Object	Diff (bytes)
MessageListView.o	+7711
MessageContainerView.o	-1472
PollAllOptionsView.o	+471
AudioSessionFeedbackGenerator.o	+392
ChatChannelSwipeableListItem.o	+196
TrailingComposerView.o	-82
ImageDecoders+Default.o	-76