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Multi-module navigation

Voyager has built-in support for multi-module navigation. Its API is based on great DI frameworks like Koin and Kodein, so should be familiar to use.

Suppose we have the following modules:

  • app: the entrypoint of our app, contains the Activity
  • feature-home: contains the root screen (HomeScreen)
  • feature-posts: contains screens related to the posts feature (ListScreen and DetailsScreen)
  • navigation: contains the screen providers used to navigate between modules, both feature-home and feature-posts imports it

To navigate from HomeScreen to the screens on feature-posts module (ListScreen and DetailsScreen), we first need to provide them. The navigation module should declare all shared screens in the app, use the ScreenProvider interface for that.

navigation/../SharedScreen.kt
sealed class SharedScreen : ScreenProvider {
    object PostList : SharedScreen()
    data class PostDetails(val id: String) : SharedScreen()
}

Now use the ScreenRegistry to register these providers. This should be done in yourApplication class.

app/../MyApp.kt
class MyApp : Application() {

    override fun onCreate() {
        super.onCreate()

        ScreenRegistry {
            register<SharedScreen.PostList> {
                ListScreen()
            }
            register<SharedScreen.PostDetails> { provider ->
                DetailsScreen(id = provider.id)
            }
        }
    }
}

You can also create a screenModule into your feature module, that way your Application class won’t be bloated by too many declarations.

feature-posts/../ScreenModule.kt
val featurePostsScreenModule = screenModule {
    register<SharedScreen.PostList> {
        ListScreen()
    }
    register<SharedScreen.PostDetails> { provider ->
        DetailsScreen(id = provider.id)
    }
}
app/../MyApp.kt
override fun onCreate() {
    super.onCreate()

    ScreenRegistry {
        featurePostsScreenModule()
    }
}

Finally, call rememberScreen() (inside a composable function) or ScreenRegistry.get() to access your screens.

feature-home/../HomeScreen.kt
class HomeScreen : Screen {

    @Composable
    override fun Content() {
        val navigator = LocalNavigator.currentOrThrow
        val postListScreen = rememberScreen(SharedScreen.PostList)
        val postDetailsScreen = rememberScreen(SharedScreen.PostDetails(id = postId))

        // navigator.push(postListScreen)
        // navigator.push(postDetailsScreen)
    }
}

Sample

Info

Source code here.