#. Before started - granting permission
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
Make sure you set the permission of accessing location in ‘AndroidManifest.xml’. We will ask for the permission of it once more as the app is running, but for that, this has to be set.
1. Requesting current location
There’s several ways of getting current location, but I’ll use with ‘FusedLocationProviderClient’. This class has ‘requestLocationUpdate’ function which we’ll use.
a. Define FusedLocationProviderClient as a global variable
private lateinit var fusedLocationProviderClient: FusedLocationProviderClient
There, and now you will use the request function, but before that, we will have to define all the parameters. And also make an instance of ‘FusedLocationProviderClient’.
private lateinit var locationRequest: LocationRequest
private lateinit var locationCallback: MyLocationCallback
private fun locationInit(){
// making an instance
fusedLocationProviderClient = FusedLocationProviderClient(this)
// initiating parameters
locationCallback = MyLocationCallback()
locationRequest = LocationRequest()
locationRequest.priority = LocationRequest.PRIORITY_HIGH_ACCURACY
}
-
‘locationCallback’ is a callback function after it gets a location information, we will define it soon.
-
‘locationRequest ‘is literally a request for a location. We changed its priority as ‘LocationRequest.PRIORITY_HIGH_ACCURACY’ to make sure it will get most accurate location data.
b. Define location callback function
We will override ‘LocationCallback’ function, here is the example;
inner class MyLocationCallback:LocationCallback(){
override fun onLocationResult(p0: LocationResult?) {
super.onLocationResult(p0)
var location = p0?.lastLocation
location?.run {
mMap.addMarker(
MarkerOptions()
.position(currentLocation)
.title("My Current Location!")
.snippet(
"Latitude : $latitude\n" +
"Longitude : $longitude"
)
)
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(LatLng(latitude, longitude), 14f))
}
}
}
Once it gets the location information, we will make camera move to the location.
c. Put them all into ‘onMapReady’
Make a function that will contain ‘requestLocationUpdates’ function, and add it into ‘OnMapReady’ as well as ‘locationInit()’.
override fun onMapReady(googleMap: GoogleMap) {
...
locationInit()
addLocationListener()
}
private fun addLocationListener(){
fusedLocationProviderClient.requestLocationUpdates(
locationRequest,
locationCallback,
null
)
}
2. Granting a permission
a. Anko library
To make this process easier, we will use Anko library. Add dependency on ‘build.gradle’ of app,
dependencies {
...
implementation "org.jetbrains.anko:anko:$anko_version"
}
and on ‘build.gradle’ of project, add the version at the end of the file.
ext.anko_version = '0.10.4'
b. Handling permission granting and denying
This is logic for checking permission. It’s quite straight forward.
private fun permissionCheck(cancel: () -> Unit, ok: () -> Unit) {
// check permission for location
if (ContextCompat.checkSelfPermission(
this,
Manifest.permission.ACCESS_FINE_LOCATION
) != PackageManager.PERMISSION_GRANTED
) {
// has denied before
if (ActivityCompat.shouldShowRequestPermissionRationale(
this,
Manifest.permission.ACCESS_FINE_LOCATION
)
) {
cancel()
// request the permission
} else {
ActivityCompat.requestPermissions(
this,
arrayOf(Manifest.permission.ACCESS_FINE_LOCATION),
// 1000 is a code for location permission
1000
)
}
// when granted
} else {
ok()
}
}
We will make an information dialog for when the permission is denied. Since we added dependency of Anke’s, it became very easy.
private fun showPermissionInfoDialog() {
alert("Need a permission for location", "reason") {
yesButton {
ActivityCompat.requestPermissions(
this@MapsActivity,
arrayOf(Manifest.permission.ACCESS_FINE_LOCATION),
1000
)
}
noButton {
System.exit(0)
}
}.show()
}
c. Overriding onResume function
put the previous permission check logic into onResume override function to let it run whenever the app is running foreground.
override fun onResume() {
super.onResume()
permissionCheck(cancel = {
// bad
showPermissionInfoDialog()
}, ok = {
// good
})
}
d. Setting a request permission listener
Once you got a permission, it will call ‘onRequestPermissionsResult’ function. It’s not necessary, but we will put ‘addLocationListener()’ for when the permission is granted.
override fun onRequestPermissionsResult(
requestCode: Int,
permissions: Array<out String>,
grantResults: IntArray
) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults)
when (requestCode) {
1000 -> {
if ((grantResults.isNotEmpty()
&& grantResults[0] == PackageManager.PERMISSION_GRANTED)
) {
// granted
addLocationListener()
} else {
toast("denied")
}
}
}
}
3. DONE!
If you went this far, it should work fine. The result should be like this;
a. When first started
b. When denied
c. When granted
Default location of Android Emulator is googleplex, so if you are seeing googleplex, you are good. If you changed the setting of your current location in Android Emulator’s setting, you would see your own location like I do.