p-lr / flow-lifecycle-observer

flow-lifecycle-observer

This library provides two Flow<T> extension functions:

1. Flow<T>.observeIn(LifecycleOwner)
2. Flow<T>.observe(LifecycleOwner, suspend (T) -> Unit)

Those functions collect the flow and:

1. Destroy its collection job on LifecycleOwner's onStop().
2. Recreates its collection job on LifecycleOwner's onStart().

Motivation

The main motivation for this library is to have lifecycle-aware collectors much like those that can be launched with:

lifecycleScope.launchWhenStarted {
    flow.collect { }
}

The issue with the above approach is that if our flow is a SharedFlow<T>, paused collectors will still be subscribed collectors, so they will have no effect on SharedFlow's SharingStarted.WhileSubscribed() and SharedFlow<T>.subscriptionCount configurations.

Read more on https://proandroiddev.com/should-we-choose-kotlins-stateflow-or-sharedflow-to-substitute-for-android-s-livedata-2d69f2bd6fa5?source=activity---post_recommended_rollup

Installation

On project-level build.gradle, add Jitpack repository:

allprojects {
  repositories {
    maven { url 'https://jitpack.io' }
  }
}

On app-level build.gradle, add dependency:

dependencies {
    implementation 'com.github.psteiger:flow-lifecycle-observer:0.1.2'
}

Usage

@AndroidEntryPoint
class NearbyUsersActivity : AppCompatActivity() {
    
    private val viewModel: NearbyUsersViewModel by viewModels()
    
    override fun onCreate(savedInstanceState: Bundle?) {
        viewModel
            .locations
            .onEach { /* new locations received */ }
            .observeIn(this)
            
        viewModel
            .users
            .observe(this) {
                /* new users received */
            }
    }
}