Found interesting behaviour of Material3 `BottomSheetScaffol

Question

Found interesting behaviour of Material3 `BottomSheetScaffold` and `NavHost` App is using `NavHost` that has nested navigation inside where few screens will be attached to main `NavHost` and other smaller one to `BottomSheetScaffold` `NavHost` In first init of the screen bottom sheet can not be hidden on swipe Then if we navigate from nav graph that has bottom sheet to other navigation on back `BottomSheetScaffold` can be hidden smile Other thing if we leave screen with `BottomSheetScaffold` expanded on back we will get ```IllegalStateException If the offset has not been initialized yet``` I am assuming that `NavHost` somehow recreates screen maybe and `rememberStandardBottomSheetState` initialised again Still figuring this out just wanted to share maybe someone already solved similar situation to this and can give some tips where to look

Tomas Škarnulis · Answer

Quick `LaunchedEffect Unit ` show that states is really recreated on back ```MapAndBottomSheet creation MapAndBottomSheet botSheet 131380672 MapAndBottomSheet scaffold 124916473 MapAndBottomSheet creation MapAndBottomSheet botSheet 195691014 MapAndBottomSheet scaffold 178577607```

Tomas Škarnulis · Answer

So i hacked my way like this `rememberStandardBottomSheetState` set skipHiddenState to false this will always let bottom sheet to be hidden on swipe Than use `rememberSaveable` to save last know `SheetValue` on `confirmValueChange` in `rememberStandardBottomSheetState` than I use `LaunchedEffect lastBootomSheetState ` and check last and current sheet value and if its not a same I use last value to move bottom sheet + save last = current Hacky so will check if it has any issues here

Tomas Škarnulis · Answer

Screen Recording 2023 09 23 at 15 55 56 mov

Patrick Steiger · Answer

It s been a while since I used NavHost but the assumption that previous nav entries are destroyed and recreated is correct at least it was back then Navigation relies on SavedState mechanism to restore state when navigating back to some destinations

jossiwolf · Answer

Which version is this on

Tomas Škarnulis · Answer

```androidx compose material3 material3 1 2 0 alpha08 androidx navigation navigation compose 2 7 0 beta02 Kotlin version 1 8 20```

jossiwolf · Answer

Please file an issue with a repro