[iOS] Application restarts when open a Camera

[yandroidUA]

Describe the bug
When the user opens a camera through the UIImagePickerController and then cancels or makes a photo the application "reloads" or losses its state. Not sure whether it's a bug of Compose or not, I'm using a following function to obtain an instance of my router:

@Composable
fun <D> rememberNavigationState(
    mapper: ((D) -> KClass<out ViewModel>?)? = null,
    initialConfiguration: TransitionScope.(NavigationState<D>) -> Unit = {},
    initialDestination: D,
    flowFinalizer: FlowFinalizer,
): NavigationState<D> {
    val manager = LocalViewModelManager.current
    return remember {
        NavigationState(
            initialDestination = initialDestination,
            initialConfiguration = initialConfiguration,
            viewModelExtension = mapper?.let { ViewModelExtension(manager = manager, mapping = it) },
            flowFinalizer = flowFinalizer
        )
    }
}

So, from my understanding it should not be reinstantiated.
From the logs I see that ComposeUIViewController invokes children composables one the application become active after the camera and with the function above my NavigationState get reinstantiated and I don't know why.

Implementation to open the Camera & Gallery

// TODO need to store somewhere globally, otherwise iOS wipes it out and these are never called back
private var imagePickerCoordinator: ImagePickerCoordinator? = null
private var imagePickerController: UIImagePickerController? = null

@Composable
internal actual fun ImagePickerResultHandler(
    source: ImageSource?,
    onRequestSourceDialog: () -> Unit,
    onShowPermissionRationale: (Permission) -> Unit,
    onLoading: (Boolean) -> Unit,
    onError: (String) -> Unit,
    onResult: (RuntimeImage) -> Unit
) {
    val fileManager = LocalFileManager.current
    val currentController = UIApplication.sharedApplication.keyWindow?.rootViewController ?: LocalUIViewController.current

    imagePickerCoordinator = remember {
        ImagePickerCoordinator(onImagePicked = { onResult(RuntimeImage(it)) }, onPickerDismissed = onRequestSourceDialog)
    }
    imagePickerController = remember(imagePickerCoordinator) {
        UIImagePickerController().apply {
            delegate = imagePickerCoordinator
        }
    }

    LaunchedEffect(source) {
        when (source) {
            ImageSource.Camera -> {
                Napier.d(tag = "IMAGE_PICKER") { "Camera" }
                imagePickerController?.sourceType = UIImagePickerControllerSourceType.UIImagePickerControllerSourceTypeCamera
                imagePickerController?.cameraCaptureMode = UIImagePickerControllerCameraCaptureMode.UIImagePickerControllerCameraCaptureModePhoto
                currentController.showViewController(imagePickerController!!, null)
            }

            ImageSource.Gallery -> {
                imagePickerController?.sourceType = UIImagePickerControllerSourceType.UIImagePickerControllerSourceTypePhotoLibrary
                currentController.showViewController(imagePickerController!!, null)
            }

            is ImageSource.RemoteUrl -> {
                fileManager.getImageFromCacheOrDownload(source.url, force = true)
                    .collect { state ->
                        when (state) {
                            is ApiState.Failed -> onError(state.reason)
                            ApiState.Idle -> {}
                            ApiState.Loading -> onLoading(true)
                            is ApiState.Succeed -> state.data.representation?.image?.let(onResult) ?: onError("")
                        }
                    }
            }
            null -> Unit
        }
    }
}

private class ImagePickerCoordinator(
    private val onImagePicked: (ByteArray) -> Unit,
    private val onPickerDismissed: () -> Unit
) : NSObject(), UIImagePickerControllerDelegateProtocol, UINavigationControllerDelegateProtocol {

    override fun imagePickerController(
        picker: UIImagePickerController,
        didFinishPickingImage: UIImage,
        editingInfo: Map<Any?, *>?
    ) {
        Napier.d(tag = "IMAGE_PICKER") { "imagePickerController" }
        picker.dismissViewControllerAnimated(true, null)
        val imageBytes = UIImagePNGRepresentation(didFinishPickingImage)?.toByteArray()
        imageBytes?.run(onImagePicked)
    }

    override fun imagePickerControllerDidCancel(picker: UIImagePickerController) {
        Napier.d(tag = "IMAGE_PICKER") { "imagePickerControllerDidCancel" }
        picker.dismissViewControllerAnimated(true, null)
        onPickerDismissed()
    }

}

Affected platforms
Select one of the platforms below:

• iOS

Versions

• Kotlin version*: 1.9.20
• Compose Multiplatform version*: 1.5.10
• OS version(s)* (required for Desktop and iOS issues): iOS 15
• OS architecture (x86 or arm64): arm64

To Reproduce

Expected behavior
Since I'm using remember I'm expecting to retrieve a same instance of the router.

Screenshots

Screen.Recording.2023-12-10.at.1.54.28.PM.mov

Additional context
Obviously, it works fine if I save the NavigationState globally, but should I do that ? From my understanding, it's something that remember is responsible, doesn't it ?

[m-sasha]

Hi, thanks for the report. Could you provide a short but complete reproducer of the problem?

[yandroidUA]

Sure, here is a sample project - archive.

XCode: Version 15.0 (15A240d)

P.S. Please, ignore the GoogleSignIn pod in the app, initially it was a reproducer for the other issue, but it doesn't impact this issue

Screen.Recording.2023-12-11.at.10.16.02.AM.mov

---

From the logs:

CONTENT
STATE: com.app.test.NavigationState@1b958020
STATE: com.app.test.NavigationState@1b958020
IMAGE_PICKER: Camera
IMAGE_PICKER: imagePickerControllerDidCancel
CONTENT
STATE: com.app.test.NavigationState@1b95ca20

Same behaviour on the real iOS device

---

I'm not sure whether it's a Compose problem, but in case it is not I'd be apriciate to receive any advice how I can handle this case

[terrakok]

@yandroidUA it is the known issue with a compose scene lifecycle: #3890

I will close this as a duplicate