AlertState renders empty content inside fullScreenCover (swift-navigation >= 2.9.1)

[andre-moneyforward]

Description

When presenting an alert using AlertState in swift-navigation v2.9.1 or higher, the alert content (title, message, and custom buttons) is omitted. Instead, an empty default alert with only an "OK" button is displayed.

• Works in: v2.8.0, v2.9.0
• Broken in: v2.9.1 and later

Code Example

AlertState Configuration

AlertState(
    title: {
        TextState("Title")
    },
    actions: {
        ButtonState(role: .cancel) { TextState("Cancel") }
        ButtonState(role: .destructive, action: .close) { TextState("Discard") }
    },
    message: {
        TextState("Message")
    }
)

View Hierarchy

var body: some View {
    TabView {
        VStack {
            Text("Tab 1")
            Button("Show Dummy View") {
                viewModel.showDummyView()
            }
        }
        .tabItem { Text("Tab 1") }

        VStack {
            Text("Tab 2")
            Button("Show Dummy View") {
                viewModel.showDummyView()
            }
        }
        .tabItem { Text("Tab 2") }
    }
    .fullScreenCover(item: $viewModel.destination.dummy) { dummyViewModel in
        NavigationStack {
            DummyView(viewModel: dummyViewModel)
                .toolbar {
                    ToolbarItem(placement: .cancellationAction) {
                        Button {
                            viewModel.closeButtonTapped()
                        } label: {
                            Image(systemName: "xmark")
                        }
                    }
                }
                .alert(
                    $viewModel.overlay.closeConfirmAlert, 
                    action: viewModel.closeAlertButtonTapped
                )
        }
    }
}

Checklist

• I have determined whether this bug is also reproducible in a vanilla SwiftUI project.
• If possible, I've reproduced the issue using the main branch of this package.
• This issue hasn't been addressed in an existing GitHub issue or discussion.

Expected behavior

The alert should display the custom title ("Title"), message ("Message"), and actions ("Cancel" and "Discard" buttons) configured in AlertState.

Simulator.Screen.Recording.-.iPhone.17.-.2026-08-14.at.14.01.32.mov

Actual behavior

The alert displays with no title, no message, and a single default "OK" button.

Simulator.Screen.Recording.-.iPhone.17.-.2026-08-14.at.13.59.19.mov

Steps to reproduce

I've attached the project to reproduce the issue.
The issue occurs on swift-navigation >= v2.9.1

1. Tap Show Dummy View
2. Tap Close Button

SampleNavigationAlertBug.zip

SwiftUI Navigation version information

>=2.9.1

Destination operating system

iOS 26.5

Xcode version information

XCode 26.5

Swift Compiler version information

6.3.2

[andre-moneyforward]

Hello! After investigating, I found that storing the information as a closure inside AlertModifier instead of a property will fix the issue.
Please let me know what you think of this approach.

AS IS

@available(iOS 15, macOS 12, tvOS 15, watchOS 8, *)
  private struct AlertModifier<Item, Actions: View, Message: View>: ViewModifier {
    @Binding var item: Item?
    var title: Text
    var actions: Actions?
    var message: Message?

    init(
      item: Binding<Item?>,
      title: (Item) -> Text,
      @ViewBuilder actions: (Binding<Item>) -> Actions,
      @ViewBuilder message: (Item) -> Message
    ) {
      self._item = item
      self.title = item.wrappedValue.map(title) ?? Text(verbatim: "")
      self.actions = Binding(unwrapping: item).map(actions)
      self.message = item.wrappedValue.map(message)
    }

    func body(content: Content) -> some View {
      let id = (item as? any Identifiable)?.id as? AnyHashable
      content
        .alert(
          title,
          isPresented: Binding($item),
          presenting: item,
          actions: { _ in actions },
          message: { _ in message }
        )
        .onChange(of: id) { [oldValue = id] newValue in
          switch (oldValue, newValue) {
          case (_?, _?):
            let newItem = item
            item = nil
            Task { item = newItem }
          case (_?, nil), (nil, _?), (nil, nil):
            break
          }
        }
    }
  }

TO BE

@available(iOS 15, macOS 12, tvOS 15, watchOS 8, *)
  private struct AlertModifier<Item, Actions: View, Message: View>: ViewModifier {
    @Binding var item: Item?
    var title: (Item) -> Text
    var actions: (Binding<Item>) -> Actions
    var message: (Item) -> Message

    init(
      item: Binding<Item?>,
      title: @escaping (Item) -> Text,
      @ViewBuilder actions: @escaping (Binding<Item>) -> Actions,
      @ViewBuilder message: @escaping (Item) -> Message
    ) {
      self._item = item
      self.title = title
      self.actions = actions
      self.message = message
    }

    func body(content: Content) -> some View {
      let id = (item as? any Identifiable)?.id as? AnyHashable
      content
        .alert(
          item.map(title) ?? Text(""),
          isPresented: Binding($item),
          presenting: item,
          actions: { _ in
            if let binding = Binding($item) {
              actions(binding)
            }
          },
          message: { message($0) }
        )
        .onChange(of: id) { [oldValue = id] newValue in
          switch (oldValue, newValue) {
          case (_?, _?):
            let newItem = item
            item = nil
            Task { item = newItem }
          case (_?, nil), (nil, _?), (nil, nil):
            break
          }
        }
    }
  }

[bruno-mfw]

@stephencelis @mbrandonw Apologies in advance for the ping. My team is also encountering this issue in a slightly different view layout. It would be great to get some guidance on this if possible. Are these use cases not supported anymore or is this a regression in your eyes? Thanks 🙏