Hello all, I am running into a race condition when trying to use a deep link into my application to ...

# compose

[Billy Newman]

Hello all, I am running into a race condition when trying to use a deep link into my application to share a file. In short in onCreate I check the incoming intent and if a file share I create and send a deep link to my app. However in my NavHost setup I also setup a startDestination. navController.handleDeepLink(…) is called in the activity before the nav host / controller has navigated to the main/home route. So my deeplink creates the compose view, then the main view is show on top of that. Any ideas? Code in thread.

[Billy Newman]

override fun onCreate(savedInstanceState: Bundle?) {
   super.onCreate(savedInstanceState)

   // handle the file share intent
   viewModel.intent.observe(this) { intent ->
      navController.handleDeepLink(intent)
   }

   // This will check the incoming intent for a file share
   viewModel.setIntent(intent)

   setContent {
      val bottomSheetState = rememberModalBottomSheetState(
         initialValue = ModalBottomSheetValue.Hidden,
         skipHalfExpanded = true
      )

      val bottomSheetNavigator = remember {
         BottomSheetNavigator(sheetState = bottomSheetState)
      }

      navController = rememberNavController(bottomSheetNavigator)
      MainScreen(
         navController = navController,
         bottomSheetNavigator = bottomSheetNavigator
      )
   }
}

ModalBottomSheetLayout(bottomSheetNavigator) {
   Scaffold(...) { paddingValues ->
         NavHost(
            navController = navController,
            startDestination = "main",  // Start at main, this will happen after deep link handler from MainActivity
            modifier = Modifier.padding(paddingValues)
         ) {
            ...
         }
      }

Is there a “recipe” for this? Maybe only handle deep links in this fashion if the app is running, and if not running just pass the intent to the MainScreen on construction? Feels wrong

[Ian Lake]

Why are you doing anything here at all? Navigation will handle the deep link for you, redirecting you to the right screen if you add a deep link with your correct action and/or mime type. Deep links aren't just for URLs

[Billy Newman]

Well that is good question, something I did not realize 🙂. Guess I am not sure how to setup compose navigation to handle incoming file share.

<intent-filter>
    <action android:name="android.intent.action.VIEW" />
    <action android:name="android.intent.action.SEND" />
    <category android:name="android.intent.category.DEFAULT" />

    <data android:scheme="content" />
    <data android:mimeType="application/octet-stream" />
</intent-filter

I know how handle that in my MainActivity, however getting the nav controller to handle a content uri sounds like what I am missing

[Ian Lake]

Just like any other deep link: https://developer.android.com/jetpack/compose/navigation#deeplinks

Just use action and mimeType instead of uriPattern

[Billy Newman]

Thanks, makes sense!

[Billy Newman]

Do you per chance know where the content uri coming in is stored?

[Ian Lake]

It could be anywhere - it could be directly streamed from a server or from an encrypted file or just a regular file another app owns that you don't have access to...except via that Uri. ContentResolver.openInputStream works to read the contents of that file in every case though

[Billy Newman]

Sorry, I think I confused the issue.

From onCreate or onNewIntent one can get incoming content uri via intent.data. Is that uri stored in the backstackEntry in the composable navigation route?

[Billy Newman]

Looks like maybe:

val intent = backstackEntry.arguments?.getParcelable(NavController.KEY_DEEP_LINK_INTENT, Intent::class.java)

[Ian Lake]

Ah, yes KEY_DEEP_LINK_INTENT is sent along through arguments