SwiftUI crash in AlertBridge.preferencesDidChange(_:)

Code Block language
0  SwiftUI                        0x1c9bf3ae8 AlertBridge.preferencesDidChange(_:) + 2604
1  SwiftUI                        0x1c97eb474 _UIHostingView.preferencesDidChange() + 412
2  SwiftUI                        0x1c98b92cc ViewGraph.updateOutputs(at:) + 180
3  SwiftUI                        0x1c9b58e10 closure #1 in closure #1 in ViewRendererHost.render(interval:updateDisplayList:) + 816
4  SwiftUI                        0x1c9b582b0 closure #1 in ViewRendererHost.render(interval:updateDisplayList:) + 524
5  SwiftUI                        0x1c9b4f1b8 ViewRendererHost.render(interval:updateDisplayList:) + 316
6  SwiftUI                        0x1c9c75748 _UIHostingView.layoutSubviews() + 160
7  SwiftUI                        0x1c9c75774 @objc _UIHostingView.layoutSubviews() + 24
8  UIKitCore                      0x195f657fc -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2144
9  QuartzCore                     0x198509494 -[CALayer layoutSublayers] + 284
10 QuartzCore                     0x19850f5ec CA::Layer::layout_if_needed(CA::Transaction*) + 468
11 QuartzCore                     0x19851a128 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 140
12 QuartzCore                     0x198462b44 CA::Context::commit_transaction(CA::Transaction*, double) + 296
13 QuartzCore                     0x19848c4e4 CA::Transaction::commit() + 676
14 UIKitCore                      0x195ada9d0 _afterCACommitHandler + 140
15 CoreFoundation                 0x19197af2c CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION + 32
16 CoreFoundation                 0x191975e20 CFRunLoopDoObservers + 420
17 CoreFoundation                 0x19197629c CFRunLoopRun + 968
18 CoreFoundation                 0x191975ba8 CFRunLoopRunSpecific + 424
19 GraphicsServices               0x19baec344 GSEventRunModal + 160
20 UIKitCore                      0x195ab13e4 UIApplicationMain + 1932
21 Kevo                           0x1029d1418 main + 17 (main.m:17)
22 libdyld.dylib                  0x1917fd8f0 start + 4

This crash happens when updating an alert item while the alert is shown. This bug is fixed in iOS 14. The following is a sample code to simulate the crash (Note that you shouldn't dismiss the first alert):

struct MessageInfo: Identifiable {
  let title: String
  let message: String
   
  var id: String {
    "\(title)-\(message)"
  }
}

struct ContentView: View {
  @State private var messageInfo: MessageInfo?

  var body: some View {
    Text("Test Alert Updating")
      .font(.largeTitle)
      .alert(item: $messageInfo) { info in
        let titleText = Text(info.title)
        let messageText = Text(info.message)
        let dismissButton = Alert.Button.default(Text("OK"))

        return Alert(title: titleText,
               message: messageText,
               dismissButton: dismissButton)
      }
      .onAppear {
        DispatchQueue.global(qos: .userInitiated).asyncAfter(deadline: .now().advanced(by: .seconds(1))) {
          messageInfo = .init(title: "Alert 1", message: "Test Alert 1")
        }
         
        DispatchQueue.global(qos: .userInitiated).asyncAfter(deadline: .now().advanced(by: .seconds(2))) {
          messageInfo = .init(title: "Alert 2", message: "Test Alert 2")
        }
      }
  }
}