dismiss is not working after multiple views were closed by UIKit

[safarafa]

Description

Child view is shown using @PresentationState in parent view, and both of them are shown in hybrid application, using UIHostingController shown as modal in new UINavigationController, and this whole modal view is dismissed (by UIKit method). When we'll show child view again, TCA's dismiss method is not working - actions are sent, the state is set to nil, but the corresponding view is still visible. It might be bug, because apparently the state is not nil after cancelling process.

Sample app

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

Using .dismiss() should remove view and set state to nil.

Actual behavior

Using .dismiss() is not removing view and the state is not nil.

Steps to reproduce

1. Download and run sample app, on device or simulator.
2. Tap "Dismiss test"
3. Tap "Tap to see first level child"
4. Tap "Dismiss using UIKit"
5. Tap "Dismiss test"
6. Tap "Dismiss this Child"
   Reproduction rate: 3/5 (sometime dismiss works).

The Composable Architecture version information

1.1.0 and below

Destination operating system

iOS 14

Xcode version information

14.3.1

Swift Compiler version information

Apple Swift version 5.8.1

[mbrandonw]

Hi @safarafa, this is the expected behavior of \.dismiss. All it does is find the closest optional state that is driving some kind of navigation and nils it out in order to undo the navigation. So, in your case it finds @PresentationState var child and nils out the child state, causing the screen to be popped off the stack.

It's worth noting that this is exactly how @Environment(\.dismiss) works in vanilla SwiftUI.

Since this is not an issue with the library I will convert this to a discussion. Feel free to continue discussing over there if you have more questions.

[safarafa]

I have to be sure you understand my issue.
After some interaction I've got something like that:
UINavigationController -> UIViewController -> UINavigationController (shown modally) -> Parent View -> Child View
if I tap "Dismiss this Child" I would have:
UINavigationController -> UIViewController -> UINavigationController (shown modally) -> Parent View
but I tap "Dismiss using UIKit" and I have
UINavigationController -> UIViewController
and then, after dismissing using UIKit, I interact to once again have:
UINavigationController -> UIViewController -> UINavigationController (shown modally) -> Parent View -> Child View
when I tap "Dismiss this Child" it is not working - it was working before UIKit dismissal of whole modal.

[stephencelis]

Hi @safarafa! Brandon and I looked at this earlier and it looks like it might be a SwiftUI bug with observing too much state.

If you remove the WithViewStore(observe: { $0 }) wrapping the NavigationStackStore here...

https://github.com/safarafa/tca-dismiss-issue/blob/c9033210009d852d6f75a36375d68fabfe735377/dismiss-test/Contents.swift#L33-L45

...and invoke self.store.send(.itemTapped) instead of viewStore.send(.itemTapped) it seems to fix the problem.

[safarafa]

Thank you for a fast response. It worked, also in the larger project in which I observed the same behaviour.

[szymhan]

Hi all, I also reproduced the unexpected behaviour and recorded short video ⬇️

It seems, that calling UIKit's dismiss(animated:) is breaking something around PresentationStore, but I'm not able to diagnose, what specifically is happening there 🤔