created a Compose Multiplatform project form Compose Multiplatform Wizard. When i ran it on ios simulator it called the

ComposeUIViewController

callback twice, though

MainViewController

called only once. I've following code in my

composeApp/src/iosMain/kotlin/main.kt

fun MainViewController(systemAppearance: (isLight: Boolean) -> Unit): UIViewController {
    println("Outside ComposeUIViewController")

    return ComposeUIViewController {
        println("Inside ComposeUIViewController")
        App() }
}

below is the output.

Possibly related : https://kotlinlang.slack.com/archives/C0346LWVBJ4/p1694447536035539

Thanks @Alejandro Rios but in my case MainViewController is called once but ComposeUiViewController is called twice which is weird. I don't know if it's default behaviour or something else.

I think you are printing any time it recomposes. In compose a Composable down the tree can perfectly trigger recomposition in its parents scope.

@Pablichjenkov App() composable is empty so there's no chance it's gonna recompose.

Yeah sounds like it shouldn't do it but internally it may trigger recomposition. I started noticing that I believe after Safe area modifiers were added

if that's the case it'll be a big disappointment as it's so weird.

I will let you know but most likely. Far from the Mac now I will verify later. But I believe last time I checked same thing. I don't care much about recompositions to be honest. Although I agree that minimizing them is important.

what about priniting inside a LaunchedEffect it's more important but having 2 recompositions is not a big deal, the second recomposition could be ignored by childs.

There shouldn't be any issues as long as there is only one composition. I.e. all

remember

-ed values are retained,

DisposableEffect.onDispose

is not called, etc.

So yes Shoaib just checked and on my side, I see the same behaviour. Notice it only happens the first time the App launches. Subsequent calls of ViewDidDisappear/ViewDidAppear don’t print anything. LaunchEffect printed only once as expected too.

Resolved https://github.com/JetBrains/compose-multiplatform/issues/3778

Ah great 😃