BlocProvider

A composable that registers StateEmitter instances (Bloc or Cubit) with BlocRegistry and makes them available to any descendant composable.

BlocProvider is the entry point for the Bloc pattern in Compose. It handles the full lifecycle of the provided blocs: they are registered when the composable enters composition and closed + deregistered when it leaves.

Overview

Wrap your root composable (or any subtree) with BlocProvider:

setContent {
    BlocProvider(listOf(
        CounterBloc(),
        AuthBloc(authService = LiveAuthService()),
    )) {
        AppNavigation()
    }
}

Dependency injection

BlocProvider is the ideal place to inject dependencies into your blocs:

BlocProvider(listOf(
    UserBloc(userService = LiveUserService()),
    AnalyticsBloc(tracker = FirebaseTracker()),
)) {
    MainScreen()
}

For Compose previews and tests, swap in mock implementations:

@Preview
@Composable
fun CounterPreview() {
    BlocProvider(listOf(CounterBloc())) {
        CounterScreen()
    }
}

Accessing blocs

Resolve blocs anywhere in the descendant tree via BlocRegistry.resolve:

@Composable
fun CounterScreen() {
    val bloc = remember { BlocRegistry.resolve(CounterBloc::class) }
    val state by bloc.stateFlow.collectAsState()
    Text("Count: ${state.count}")
}

Parameters