hey I m playing with BottomNavigation and Jetpack Navigation kotlinlang #compose

hey! I’m playing with BottomNavigation and Jetpack Navigation and I did an sample based on @Afzal Najam post ( thanks man🙏 https://afzaln.com/multiple-navigation-graphs-with-jetpack-compose-navigation/) Here’s my code: https://gist.github.com/nglauber/5061cbbafd63488131380b09c8943ad7 I have two questions: 1. When the second tab is selected and displaying its root content, is there a way to display the first tab when the user presses the system back key? 2. Could someone point out where can I find a way to save the

LazyColumn

scroll position? In my sample, the first tab is a list.

ok. I fixed #2 hoisting

rememberLazyListState()

Afzal Najam

01/04/2021, 2:29 AM

I think if you want to display the first tab with the back button, you might want to put both tabs in a single nav graph. The second tab wouldn't need its own nav graph in this use case, right?

nglauber

01/04/2021, 2:42 AM

I tried the approach presented in documentation sample… but when I use a single nav graph and reselect the first tab, I missed the first tab back stack. Only the root composable of the first tab is displayed.

Another idea I had was: set a

NavHost

as a child of

Scaffold

, and the

NavHost

has two other `NavHost`’s inside of it (one for each tab)… But didn’t work 😕

Karthick

01/04/2021, 3:06 AM

May listen to back button click and do your logic manually

nglauber

01/04/2021, 3:16 AM

@Karthick I guess this should the simpler way to deal with this specific case… But I’m wondering why

NavHost

is not working with nested `NavHost`s… 🤔

Afzal Najam

01/04/2021, 4:36 AM

Nelson, there's a new way to deal with nested nav graphs. I'm not sure it's in the documentation yet but it's in the Androidx samples. https://github.com/androidx/androidx/blob/androidx-main/navigation/navigation-compose/samples/src/main/java/androidx/navigation/compose/samples/NavigationSamples.kt https://github.com/androidx/androidx/blob/androidx-main/navigation/navigation-compose/integration-tests/navigation-demos/src/main/java/androidx/navigation/compose/demos/NestedNavDemo.kt

Kshitij Patil

01/04/2021, 7:20 AM

I had similar requirement and I implemented self navigation for the fragment hosting the

BottomNavigation

as launching the same fragment will ultimately start with First Tab but you'll lose all the navgraph states with this approach

nglauber

01/04/2021, 12:41 PM

yeah… I’m having this same result @Kshitij Patil 😕 Basically, to summarize, I want to simulate the same navigation approach used by YouTube.

It worked! 🎉 Thanks to this code by @Vinay Gaba 👏 https://github.com/airbnb/Showkase/blob/9301d3dc49fa3174b813931a332d56c5565ea8ad/showkase/src/main/java/com/airbnb/android/showkase/ui/BackButtonHandler.kt

Yahor

01/04/2021, 5:23 PM

Two navigation graphs can solve the issue #1 https://github.com/egorikftp/BelarusResistanceFlag

👍 1

nglauber

01/04/2021, 5:23 PM

I did that 😉 thanks @Yahor

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