Monitoring GPS and Permission checks using LiveData

In our last project, we had to implement checks to ensure GPS is enabled on the device and Location Permission is granted by the user. It is important to highlight that both are critically needed to ensure the app can perform Location Tracking in background.

Our best bet was to inform visually when the app is in the foreground or background in order to encourage the user to fulfill one or both of these requirements. This was only possible when UI (Activity/Fragment) and Service can listen to changes in GPS and Runtime Permission and react accordingly.

I faced several challenges while doing that and decided to share my learnings and solution.

Transcript

1. Monitoring GPS and Permission checks using LiveData Wahib Ul Haq @wahibhaq https://ki-labs.com
5. LiveData is an observable data holder and lifecycle-aware. It lets the components in your app, usually the UI, observe LiveData objects for changes.
6. GPS Status LiveData
7. class GpsStatusLiveData(private val context: Context) : LiveData<GpsStatus>() { }
8. class GpsStatusLiveData(private val context: Context) : LiveData<GpsStatus>() { }
9. sealed class GpsStatus { data class GpsIsDisabled(val message: Int) : GpsStatus() data class GpsIsEnabled(val message: Int) : GpsStatus() }
10. override fun onInactive() = unregisterReceiver() override fun onActive() { registerReceiver() checkGpsAndReact() }
11. private fun registerReceiver() = context.registerReceiver(gpsSwitchStateReceiver, IntentFilter(LocationManager.PROVIDERS_CHANGED_ACTION)) private fun unregisterReceiver() = context.unregisterReceiver(gpsSwitchStateReceiver)
12. private val gpsSwitchStateReceiver = object : BroadcastReceiver() { override fun onReceive(context: Context, intent: Intent) = checkGpsAndReact() }
13. private fun checkGpsAndReact() = if (isLocationEnabled()) { postValue(GpsStatus.GpsIsEnabled(R.string.gps_status_enabled)) } else { postValue(GpsStatus.GpsIsDisabled(R.string.gps_status_disabled)) }
14. Observing GPS Status LiveData
15. //ViewModel val gpsStatusLiveData = GpsStatusLiveData(application)
16. //ViewModel val gpsStatusLiveData = GpsStatusLiveData(application) Think carefully before sharing a LiveData instance across consumers
17. //onCreate() viewModel.gpsStatusLiveData.observe(this, gpsObserver)
18. private val gpsObserver = Observer<GpsStatus> { status -> status?.let { when (status) { is GpsStatus.GpsIsEnabled -> { //update UI } is GpsStatus.GpsIsDisabled -> { //update UI } } } }
19. Location Permission Status LiveData
20. Source: Kaspersky.com
24. class PermissionStatusLiveData(private val context: Context) : LiveData<PermissionStatus>() { }
25. sealed class PermissionStatus { data class Granted(val message: Int) : PermissionStatus() data class Denied(val message: Int) : PermissionStatus() }
26. override fun onActive() = handlePermissionCheck() private fun handlePermissionCheck() { val isPermissionGranted = ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED }
27. private fun handlePermissionCheck() { val isPermissionGranted = ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED if (isPermissionGranted) postValue(PermissionStatus.Granted(R.string.permission_status_granted)) else postValue(PermissionStatus.Denied(R.string.permission_status_denied_show_notif)) }
28. Observing Permission Status LiveData
31. class LocationService : LifecycleService() { }
32. private val gpsObserver = Observer<GpsStatus> { status -> status?.let { handleGpsStatus(status) } } private val permissionObserver = Observer<PermissionStatus> { status -> status?.let { handlePermissionStatus(status) } }
33. private val pairObserver = Observer<Pair<PermissionStatus, GpsStatus>> { pair -> pair?.let { handlePermissionStatus(pair.first) handleGpsStatus(pair.second) } }
34. fun <A, B> combineLatest(a: LiveData<A>, b: LiveData<B>): MutableLiveData<Pair<A, B>> { return MediatorLiveData<Pair<A, B>>().apply { } }
35. //onCreate() gpsAndPermissionStatusLiveData = PermissionStatusLiveData(application).combineLatestWith(GpsStatusLiveData(application))
36. //onStartCommand() gpsAndPermissionStatusLiveData.observe(this, pairObserver)
37. More Stuff observeForever(Observer)
38. More Stuff SingeLiveEvent
39. More Stuff SingeLiveEvent
40. More Stuff SingeLiveEvent A lifecycle-aware observable that sends only new updates after subscription, used for events like navigation and Snackbar messages.
41. Thanks for listening! Wahib Ul Haq @wahibhaq https://ki-labs.com