Permission and UI widget manipulation in MVVM

MapFragment.kt

class MapFragment : SupportMapFragment() {

    private lateinit var mapViewModel: MapViewModel

    private lateinit var googleMap: GoogleMap

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        mapViewModel.viewActionLiveData.observe(
            this,
            Observer { viewAction: ViewAction ->
                when (viewAction) {
                    is ViewAction.EnableMapLocationOptions -> setUiForLocationEnabled(viewAction.mapLocationOptionsModel)
                    is ViewAction.AskPermission -> ActivityCompat.requestPermissions(requireActivity(), viewAction.permissions, 0)
                }.exhaustive
            }
        )

        /* ... */

        getMapAsync {
            googleMap = it
            
            /* ... */
        }
    }

    /* ... */  
  
    private fun setUiForLocationEnabled(mapLocationOptionsModel: MapLocationOptionsModel) {
        googleMap.isMyLocationEnabled = mapLocationOptionsModel.isMyLocationEnabled
        googleMap.uiSettings.isMyLocationButtonEnabled = mapLocationOptionsModel.isMyLocationButtonEnabled
    }

    override fun onResume() {
        super.onResume()

        mapViewModel.refreshPermissions()
    }
}

MapViewModel.kt

class MapViewModel(
    private val permissionChecker: PermissionChecker
    /* ... */
) : ViewModel() {

    private val _viewActionLiveData = SingleLiveEvent<ViewAction>()
    val viewActionLiveData: LiveData<ViewAction> = _viewActionLiveData

    /* ... */
    
    fun refreshPermissions() {
        if (!permissionChecker.hasLocationPermission()) {
            _viewActionLiveData.value = ViewAction.AskPermission(arrayOf(android.Manifest.permission.ACCESS_FINE_LOCATION))
        }
    }

    sealed class ViewAction {
        data class EnableMapLocationOptions(val mapLocationOptionsModel: MapLocationOptionsModel) : ViewAction()

        class AskPermission(val permissions: Array<String>) : ViewAction()
    }

    data class MapLocationOptionsModel(
        val isMyLocationEnabled: Boolean,
        val isMyLocationButtonEnabled: Boolean
    )
}

PermissionChecker.kt

class PermissionChecker(private val application: Application) {

    fun hasLocationPermission(): Boolean =
        ContextCompat.checkSelfPermission(application, android.Manifest.permission.ACCESS_FINE_LOCATION) == PERMISSION_GRANTED
}