Rumble Hang - SwiftUI Accessibility Reproduction Project

Purpose

This project reproduces a hang issue in SwiftUI applications when using:

• Accessibility Inspector (iOS Simulator)
• VoiceOver (Physical iOS Device)

The hang occurs with a specific SwiftUI view hierarchy pattern involving nested LazyVStack components with dynamic content loading.

---

Quick Reproduction Steps

Steps to Reproduce the Hang

1. Build and run the project in the iOS Simulator
2. Enable Accessibility Inspector:
   • Xcode → Open Developer Tool → Accessibility Inspector
   • Select your running simulator
   • Click the Inspection (eye) icon to enable it
3. Navigate to the test view:
   • In the app, tap "Show Nested LazyVStack Page"
4. Trigger the hang:
   • Start scrolling down through the list
   • The app will become unresponsive and hang
   • The hang typically occurs when scrolling triggers new sections to load

Where the Hang Occurs

The hang happens in NestedLazyVStackView.swift during scrolling:

ScrollView {
    LazyVStack {                              // Outer LazyVStack
        ForEach(outerSections) { section in
            VStack {
                Text("Section #\(section)")
                LazyVStack {                  // Inner LazyVStack (NESTED!)
                    ForEach(innerRows) { row in
                        Text("Row #\(row)")
                            .onAppear {       // ← HANG OCCURS HERE
                                loadMoreInner() // When this triggers with Accessibility active
                            }
                    }
                }
            }
            .onAppear {                       // ← OR HERE
                loadMoreOuter()               // When this triggers
            }
        }
    }
}

---

The Pattern

View Structure

The critical pattern that causes the hang:

ScrollView {
    LazyVStack {                    // Level 1: Outer lazy container
        ForEach(...) { section in
            VStack {
                LazyVStack {        // Level 2: Inner lazy container (NESTED!)
                    ForEach(...) { row in
                        Text(...)
                            .onAppear { ... }  // Dynamic loading
                    }
                }
            }
            .onAppear { ... }  // Dynamic loading
        }
    }
}

This pattern is found in NestedLazyVStackView.swift.

---

Project Structure

Key Files

• ContentView.swift - Root view with simple navigation (tap "Show Nested LazyVStack Page")
• NestedLazyVStackView.swift - THE REPRODUCTION CASE - Contains nested LazyVStack with infinite scroll
• AppDelegate.swift - Application lifecycle methods
• Models.swift - Article data models (not used in reproduction)
• ArticleViews.swift - Alternative reproduction case (not used in primary test)
• MainTabView.swift - Tab bar structure (not used in primary test)

Dependencies

• SDWebImageSwiftUI: 2.2.7

Note: This project does not include any third-party SDKs. The hang is a pure SwiftUI + Accessibility issue.

---

Build & Run

1. Open Rumble_Hang.xcodeproj in Xcode
2. Select a simulator (iPhone 15 or later recommended, I have reproduce on ios 26.2)
3. Build and run (⌘R)
4. Follow the "Quick Reproduction Steps" above

---

Workarounds

If the hang occurs in your application, there are two known workarounds:

Option 1: Replace Nested LazyVStack with VStack

// BEFORE (causes hang)
LazyVStack {
    ForEach(...) { section in
        LazyVStack {  // ← Inner nested lazy
            ForEach(...) { row in
                ...
            }
        }
    }
}

// AFTER (resolves hang)
LazyVStack {
    ForEach(...) { section in
        VStack {      // ← Changed to eager container
            ForEach(...) { row in
                ...
            }
        }
    }
}

This eliminates the nested lazy behavior and prevents the hang.

Option 2: Wrap in TabView

Interesting finding: The hang does not occur when the view is embedded within a TabView:

TabView {
    NavigationStack {
        // Your view with nested LazyVStack
        NestedLazyVStackView()
    }
    .tabItem { ... }
}

The TabView appears to isolate or buffer the nested LazyVStack from the accessibility system in a way that prevents the hang. This workaround maintains the lazy loading behavior while avoiding the conflict.

---

Customer Context

This reproduction project is based on real customer code from the Rumble iOS App (News reading application), where a similar view hierarchy pattern was used. The hang was reported when users enabled VoiceOver or when testing with Accessibility Inspector.

---

Notes

• This is a pure SwiftUI + Accessibility issue, not related to any third-party SDK
• Only reported by a small number of customers in specific scenarios
• The exact root cause is still under investigation
• The workarounds (replacing nested LazyVStack with VStack, or using TabView) have been validated