{Alert} An "ifLet" at "/ContentView.swift:132" received a presentation action when destination state was absent.

[anansadiya94]

I'm using the new navigation patterns for alerts and receiving a run time warning after tapping the exit button in the alert.
I thought it might have to do with my project, so I created a new project, and here is the code:

import SwiftUI
import ComposableArchitecture

struct Feature: Reducer {
    struct State: Equatable {
        @PresentationState var alert: AlertState<AlertAction>?
    }
    
    enum Action: Equatable {
        case exitTapped
        case alert(PresentationAction<AlertAction>)
    }
    
    enum AlertAction: Equatable {
        case exitConfirmed
    }
    
    var body: some Reducer<State, Action> {
        Reduce { state, action in
            switch action {
            case .exitTapped:
                state.alert = .init(
                    title: {
                        TextState("Are you sure you want to exit?")
                    },
                    actions: {
                        ButtonState(role: .destructive, action: .exitConfirmed) {
                            TextState("Yes")
                        }
                    }
                )
                return .none
            case .alert(.presented(.exitConfirmed)):
                print("Exit confirmed!")
                return .none
                
            case .alert:
                return .none
            }
        }
        .ifLet(\.$alert, action: /Action.alert)
    }
}
    

struct ContentView: View {
    let store: StoreOf<Feature> = Store(initialState: Feature.State(), reducer: { Feature()._printChanges() })
    var body: some View {
        WithViewStore(store, observe: { $0 }) { viewStore in
            VStack {
                Button {
                    viewStore.send(.exitTapped)
                } label: {
                    Text("Exit!")
                }
            }
        }
        .alert(store: store.scope(state: \.$alert, action: { .alert($0) }))
    }
}

#Preview {
    ContentView()
}

I'm using the 1.2.0 TCA version and it's reproducible with both Xcode 14.3.1 and 15.0.
Please let me know what I'm doing wrong.
Thanks,

[mbrandonw]

Hi @anansadiya94, I am not able to reproduce this problem. I copied and pasted your code into a project and it seems to work fine with no runtime warning. Could you package up a project that reproduces the problem?

[anansadiya94]

Hi @mbrandonw , I tested it again and it seems to be reproducible on iOS 15 only. Sorry for not mentioning it before, but I was using my iOS 15 testing device and caught the runtime warning there. Please give it a try running it on iOS 15 simulator, I used iPhone SE (3rd generation) 15.5. And keep me posted.
Attaching the Project, if you still need it.
Thanks,

[stephencelis]

@anansadiya94 iOS 15 alerts appear to write dismissal to their bindings before executing their action closure, which is why you see this discrepancy. I'm not sure it's worth working around in our library, though, since it technically is revealing a potential issue, like if the action depended on the current state of the alert, which would be nil at that moment. It's all a bit tricky, but at least the behavior has improved in iOS 16. I think you can safely ignore the warning we emit in debug iOS 15 builds, though! It's just good to be aware of what the warning means.