Flow - lighweight architecture article - Service

ForegroundOnlyLocationService.kt

@AndroidEntryPoint
class ForegroundOnlyLocationService : LifecycleService() {
    ...
  
    // Data store (in this case, the SharedLocationManager) that the service will observe, injected via Hilt
    @Inject
    lateinit var repository: LocationRepository

    // Get a reference to the Job from the Flow so we can stop it from UI events
    private var locationFlow: Job? = null
    ...
  
    fun subscribeToLocationUpdates() {
        SharedPreferenceUtil.saveLocationTrackingPref(this, true)
        
        // Binding to this service doesn't actually trigger onStartCommand(). That is needed to
        // ensure this Service can be promoted to a foreground service, i.e., the service needs to
        // be officially started (which we do here).
        startService(Intent(applicationContext, ForegroundOnlyLocationService::class.java))

        // Observe locations via Flow as they are generated by the repository
        locationFlow = repository.getLocations()
            .flowWithLifecycle(lifecycle, Lifecycle.State.STARTED)
            .onEach {
                Log.d(TAG, "Service location: ${it.toText()}")
                notificationManager.notify(
                    NOTIFICATION_ID,
                    generateNotification(currentLocation))
                ...
            }
            .launchIn(lifecycleScope)
    }
    
    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        val cancelLocationTrackingFromNotification =
                intent?.getBooleanExtra(EXTRA_CANCEL_LOCATION_TRACKING_FROM_NOTIFICATION, false)

        if (cancelLocationTrackingFromNotification == true) {
            unsubscribeToLocationUpdates()
            stopSelf()
        }
        // Tells the system not to recreate the service after it's been killed.
        return super.onStartCommand(intent, flags, START_NOT_STICKY)
    }
    
    fun unsubscribeToLocationUpdates() {
        locationFlow?.cancel()
        SharedPreferenceUtil.saveLocationTrackingPref(this, false)
    }
    ...
}