Hey everyone, I’m facing an issue in my Compose Mu...

# compose

[Vaibhav Jaiswal]

Hey everyone, I’m facing an issue in my Compose Multi-platform app, with screens being recreated when navigating back
I’m using Voyager for Navigation

When I navigate back
• The Lazy Column Scroll State is lost (I’m using rememberLazyListState()
• ViewPager State is lost (I’m using rememberPagerState()
• All Launched Effects of all Composables run again (LaunchedEffect(Unit))
• Compose States reset to their default value for a small amount of time, then get back to original value
As of now, I’ve been using a workaround, i.e. to store lazyListState, viewPager State in ViewModel, which I dont think is right

Does anyone know, if this is the default behaviour of Compose, or its Voyager’s Navigation issue?

Cc: @लातों वाला भूत

[Arkadii Ivanov]

Compose itself doesn't do anything with preserving the state between screens. It's a responsibility for navigation. Usually navigation libraries use SaveableStateHolder, and I remember Voyager used it as well, but I might be wrong.

[Arkadii Ivanov]

So, you might be using Voyager incorrectly, or maybe there is a bug in the library. Worth checking with docs.

[Vaibhav Jaiswal]

@Arkadii Ivanov thanks
Does this kind of behaviour normally happen in AndroidX Navigation Compose?

[Arkadii Ivanov]

I'm pretty sure navigation-compose preserves the UI state, as well as all other navigation libraries.

[Suresh Maidaragi]

@Arkadii Ivanov we use Pre-compose library that also that similar behaviour,

[Arkadii Ivanov]

What I'm saying is that it's by design that all remember-ed values are lost, as a screen Composable exits the composition when another screen is pushed to the stack. But the screen Composable should correctly restore its state, r.g. LazyColumn is able to keep its scroll position. Make sure you keep your screen data in a ViewModel (or whatever concept is provided by the navigation library).

[Vaibhav Jaiswal]

@Arkadii Ivanov All my data is in viewmodel and is restored again
Its just the ui related states, like fab expansion state, scroll state, viewpager state, all is lost
All remembered states get reset

[Arkadii Ivanov]

This is by design I believe, rememberSaveable should do the trick.

[Vaibhav Jaiswal]

@Arkadii Ivanov does that work in Compose Multiplatform, targeting Android and iOS only?

[Arkadii Ivanov]

I think yes, but the UI state is only preserved while the process is alive.

[Arkadii Ivanov]

Decompose is able to preserve the state over process death, but only for business logic (aka ViewModel). Not sure about other libraries.

[Vaibhav Jaiswal]

I'm considering shifting to Decompose, when navigating back to a screen does it preserve the ui states, or is it the same as what I'm facing with Voyager?

[Arkadii Ivanov]

I think all navigation libraries are kinda the same in this regard. All remember-ed state is lost when another screen is pushed to the stack, all `LaunchedEffect`s are terminated, etc. But rememberSaveable-ed state should be restored correctly (as long as there as no process death involved).