Flow - lightweight architecture article - SharedLocationManager

SharedLocationManager.kt

/**
 * Wraps the LocationServices and fused location provider in callbackFlow
 *
 * Derived in part from https://github.com/android/location-samples/blob/main/LocationUpdatesBackgroundKotlin/app/src/main/java/com/google/android/gms/location/sample/locationupdatesbackgroundkotlin/data/MyLocationManager.kt
 * and https://github.com/googlecodelabs/kotlin-coroutines/blob/master/ktx-library-codelab/step-06/myktxlibrary/src/main/java/com/example/android/myktxlibrary/LocationUtils.kt
 */
class SharedLocationManager constructor(
    private val context: Context,
    externalScope: CoroutineScope
) {
    ...
    // Set up the Fused Location Provider and LocationRequest
    private val fusedLocationClient: ...
    private val locationRequest = ...

    @ExperimentalCoroutinesApi
    @SuppressLint("MissingPermission")
    private val _locationUpdates = callbackFlow<Location> {
        val callback = object : LocationCallback() {
            override fun onLocationResult(result: LocationResult?) {
                result ?: return
                Log.d(TAG, "New location: ${result.lastLocation.toText()}")
                // Send the new location to the Flow observers
                trySend(result.lastLocation)
            }
        }
        ...
        Log.d(TAG, "Starting location updates")

        fusedLocationClient.requestLocationUpdates(
            locationRequest,
            callback,
            Looper.getMainLooper()
        ).addOnFailureListener { e ->
            close(e) // in case of exception, close the Flow
        }

        awaitClose {
            Log.d(TAG, "Stopping location updates")
            fusedLocationClient.removeLocationUpdates(callback) // clean up when Flow collection ends
        }
    }.shareIn(
        externalScope,
        replay = 0,
        started = SharingStarted.WhileSubscribed()
    )

    @ExperimentalCoroutinesApi
    fun locationFlow(): Flow<Location> {
        return _locationUpdates
    }
}