Integration of the Google location API requires implementation of GoogleAPIClient, ConnectionCallbacks, and connection failed listeners by MapsActivity. Let us proceed and make the changes to the MapsActivity. Earlier, we had the MapsActivity extend AppCompatActivity and implement the OnMapReadyCallback interface. Now, since we need to use the location API's we have to also implement the GoogleAPIClient, ConnectionCallbacks, and onConnectionFailedListener as shown here:

class MapsActivity : AppCompatActivity(), OnMapReadyCallback ,GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, com.google.android.gms.location.LocationListener {

We declare the variables required for GoogleMap and other variables to store the latitude and longitude received from the user and also from the location API:

    private lateinit var mMap: GoogleMap
    private var newLat: Double? = null
    private var newLang: Double? = null
    private var chennai: LatLng? = null
 
    private var AlarmLat: Double? = null
    private var AlarmLong: Double? = null
    private var UserLat: Double? = null
    private var UserLong: Double? = null
 
     //location variables
 
    private val TAG = "MapsActivity"
    private lateinit var mGoogleApiClient: GoogleApiClient
    private var mLocationManager: LocationManager? = null
    lateinit var mLocation: Location
    private var mLocationRequest: LocationRequest? = null

We declare the UPDATE_INTERVAL, the interval in which we would like to receive the updates from the location API, and FASTEST_INTERVAL, the rate at which our app can handle the update. We also declare the LocationManager variable:

     private val UPDATE_INTERVAL = 10000.toLong() // 10 seconds rate at 
     //  which we would like to receive the updates
     private val FASTEST_INTERVAL: Long = 5000 // 5 seconds - rate at  
     //  which app can handle the update
     lateinit var locationManager: LocationManager

In the onCreate function, we set the content view for the UI and also ensure the GoogleApiClient is instantiated. We also request that the user enables the location is as follows:

onCreate():

   override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_maps)
         // Obtain the SupportMapFragment and get notified when the map    
         is ready to be used.
         val mapFragment = supportFragmentManager
                 .findFragmentById(R.id.map) as SupportMapFragment
         mapFragment.getMapAsync(this)
         
 
         mGoogleApiClient = GoogleApiClient.Builder(this)
                 .addConnectionCallbacks(this)
                 .addOnConnectionFailedListener(this)
                 .addApi(LocationServices.API)
                 .build()
 
         mLocationManager =   
         this.getSystemService(Context.LOCATION_SERVICE) as  
         LocationManager
         checkLocation()
 }