Problem with alert in iOS4.5

Question

capibara1969 OP

Created May ’21

Replies 6

Boosts 0

Views 1.5k

Participants 3

When I run the following code, it works fine on iOS 4.4 and up, but on iOS 4.5, the alert does not show up and the following log is output.

2021-05-08 18:21:34.680280+0900 SampleProject12.5[2534:139985] [Presentation] Attempt to present <SwiftUI.PlatformAlertController: 0x7ff27200ce00> on <_TtGC7SwiftUI41StyleContextSplitViewNavigationControllerVS14NoStyleContext: 0x7ff26f825000> (from <_TtGC7SwiftUIP13$7fff5695965428DestinationHostingControllerVS7AnyView: 0x7ff271c06180>) whose view is not in the window hierarchy.

Code Block import SwiftUIstruct ContentView: View {  var body: some View {    NavigationView {      List {        NavigationLink(destination: NextView()) {          Text("Next View")        }      }    }  }}struct NextView: View {  @State private var showingAlert = false     var body: some View {    Button("Show Alert") {      showingAlert = true    }    .alert(isPresented: $showingAlert) {      Alert(title: Text("Alert!"))    }    .onAppear {      showingAlert = true    }  }}

Answered by workingdogintokyo in 673900022

If you are trying to display an alert on screen transition, then you could try this
as a workaround until it is fixed properly:

Code Block .onAppear {		DispatchQueue.main.async {				Thread.sleep(forTimeInterval: 0.01)				showingAlert = true		}}

Boost

Answer 1

workingdogintokyo OP

May ’21

seems the Alert is trying to render before the View is fully setup, try this:

Code Block     .onAppear {    //  showingAlert = true    }

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Answer 2

capibara1969 OP

May ’21

Hi, thanks for your reply.
I am trying to display an alert on screen transition.
I believe this is an iOS 4.5 issue, as it worked up to iOS 4.4.
I have reported this to the Feedback Assistant.

1

Answer 3

Claude31 OP

May ’21

It effectively works correctly on 14.4 (not 4.4😉) simulator.

The error speaks of splitView. I do not see it in the posted code.

There are some issues with List.
Could you try, just for testing, to replace List by VStack ?

There seems to have been some change with 14.5:
https://forums.swift.org/t/14-5-beta3-navigationlink-unexpected-pop/45279

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Answer 4

workingdogintokyo OP

May ’21

Accepted Answer

If you are trying to display an alert on screen transition, then you could try this
as a workaround until it is fixed properly:

Code Block .onAppear {		DispatchQueue.main.async {				Thread.sleep(forTimeInterval: 0.01)				showingAlert = true		}}

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Answer 5

capibara1969 OP

May ’21

Thank you very much. I was able to achieve what I wanted to do. > workingdogintokyo

Thanks for pointing that out, it's 14.5. > Claude31

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Answer 6

capibara1969 OP

Sep ’21

I have confirmed that this issue has been resolved in iOS15. According to Apple, it was fixed in iOS15 beta7.

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