Was trying to run the template, and it runs fine w...

# compose-ios

[humbledroid]

Was trying to run the template, and it runs fine with the button and text, wanted to play a bit more around flows and ui state mutation,
Considering that I may want to run an API call or anything which may be needed to run off the main thread and I setup a view controller
I have the below snipped which runs on Android as expected, but on ios the UI remains on the initial state of loading...

class FakeVC {
    data class ViewState(val loading:Boolean = false, val content:String = "loading...")

    private val screenState = MutableStateFlow(ViewState())
    fun screenState() = screenState.asStateFlow()
    fun somFakeCall(){
        coroutineScope.launch {
            screenState.value = screenState.value.copy(loading = true)
            withContext(Dispatchers.Default){
                delay(3000)
            }
            screenState.value = screenState.value.copy(loading = false, content = "I am here after api call")
        }

    }

//... some clear logic for scope on dispose
}

and the mutated state data change is never seen on the ui , and here is the compose code which is

val fvc = FakeVC()
MaterialTheme {
    LaunchedEffect(Unit){
        fvc.somFakeCall()
    }

    val viewState by l.screenState().collectAsState()

    Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center){
        Text(viewState.content)
        if(viewState.loading){
            Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center){
                CircularProgressIndicator(modifier = Modifier.align(Alignment.Center), color = Color.Red)
            }
        }
    }

    DisposableEffect(Unit){
        onDispose {
            fvc.clear()
        }
    }
}

this I tried it with latest coroutines and even with native-mt, is there anything else that may be required to setup it correctly when running it on iOS, as this works as expected on Android.

[Dima Avdeev]

Hello!
Can you please move code samples inside this thread 🧵 for easier reading of an overall #compose-ios channel?

[Dima Avdeev]

I think in the code there is a mistake in this line:

fun screenState() = screenState.asStateFlow()

[humbledroid]

I guess, this works, as I just want to expose it as ready only.

[Dima Avdeev]

This function always creates a new StateFlow

[humbledroid]

it will create it only once, per class instantiation

[Dima Avdeev]

Can you please create a reproducible sample on GitHub that will works on Android and fails on iOS?

[Dima Avdeev]

If you want to expose it as StateFlow, you can just do this:

fun screenState(): StateFlow<ViewState> = screenState

[humbledroid]

either way, it will be same thing, i tried this as well, but the same result, here is the code repository.
https://github.com/carotkut94/sample

[Dima Avdeev]

Thanks, you should change this line:

val l = remember { FakeVC() }

[humbledroid]

🤦 yeah, this works, but i am surprised that it worked on Android, i guess the root composable was getting recomposed because of which it always had a new instance of the FakeVC in ios, but on android it was happening in a different way. Will dig deep, Thanks @Dima Avdeev

[Dima Avdeev]

I don't know why it is working on Android. I think it is better to use remember on Android as well.
Or save state holders in outside Comosable functions.