How to call `NavController` from `Activity.onNewIntent()` ?

# compose

[julioromano]

How to call NavController from Activity.onNewIntent() ?

[julioromano]

I used to do this 👇 with fragment navigation, but now I’m not sure how to grab a reference to NavController within onNewIntent() which is outside of the composition.

override fun onNewIntent(intent: Intent?) {
    super.onNewIntent(intent)
    navController.handleDeepLink(intent)
  }

For instance: I’ve tried grabbing a ref to NavController as a side effect with .apply like:

setContent {
        val navController = rememberNavController().apply {
          navController = this // navController is a global instance var

But I end up getting crashes at runtime because that global var is not initialized yet when onNewIntent() is called.

[allan.conda]

Have you tried making a SideEffect with Intent as key? not sure if that’s a bad idea, but might work.

private var intent : Intent? by mutableStateOf(null)

fun onNewIntent(newIntent) {
  intent = newIntent
}

setContent {
  val navControler = ...
  SideEffect(Intent) {
    navController...
  }
}

[allan.conda]

actually, that idea looks horrible lol. If you’re using ViewModel, I think you can update the navigation state depending on the intent, Then your composable navigates based on the navigation state..

[Ian Lake]

The correct answer is to not use a launchMode at all. NavController will handle deep links for you then

[allan.conda]

Right, forgot about deep links support in the Navigation library.

[julioromano]

@Ian Lake though launchMode="singleTask" still seems a legit use case for single activity apps. It wouldn’t make sense for those apps to have multiple instances of their activity created by the system. What to do in such case?

Docs are currently mentioning this here: https://developer.android.com/reference/kotlin/androidx/navigation/NavController#handledeeplink

[Ian Lake]

No, you should never use singleTask either. That breaks implicit deep links on other app's tasks (something that Navigation also fully supports)