If your app needs to request location or receive permission updates, the device needs to enable the appropriate system settings, such as GPS or Wi-Fi scanning. Rather than directly enabling services such as the device's GPS, your app specifies the required level of accuracy/power consumption and desired update interval, and the device automatically makes the appropriate changes to system settings. These settings are defined by the {@code LocationRequest} data object.
This lesson shows you how to use the Settings API to check which settings are enabled, and present the Location Settings dialog for the user to update their settings with a single tap.
In order to use the location services provided by Google Play Services and the fused location provider, connect your app using the Google API Client, then check the current location settings and prompt the user to enable the required settings if needed. For details on connecting with the Google API client, see Getting the Last Known Location.
Apps that use location services must request location permissions. For this
lesson, coarse location detection is sufficient. Request this permission
with the uses-permission element in your app manifest, as shown
in the following example:
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.google.android.gms.location.sample.locationupdates" >
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
</manifest>
If the device is running Android 6.0 or higher, and your app's target SDK is 23 or higher, the app has to list the permissions in the manifest and request those permissions at run time. For more information, see Requesting Permissions at Run Time.
To store parameters for requests to the fused location provider, create a {@code LocationRequest}. The parameters determine the level of accuracy for location requests. For details of all available location request options, see the {@code LocationRequest} class reference. This lesson sets the update interval, fastest update interval, and priority, as described below:
{@code setPriority()} - This method sets the priority of the request, which gives the Google Play services location services a strong hint about which location sources to use. The following values are supported:
Create the location request and set the parameters as shown in this code sample:
protected void createLocationRequest() {
LocationRequest mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(10000);
mLocationRequest.setFastestInterval(5000);
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}
The priority of {@code PRIORITY_HIGH_ACCURACY}, combined with the {@link android.Manifest.permission#ACCESS_FINE_LOCATION ACCESS_FINE_LOCATION} permission setting that you've defined in the app manifest, and a fast update interval of 5000 milliseconds (5 seconds), causes the fused location provider to return location updates that are accurate to within a few feet. This approach is appropriate for mapping apps that display the location in real time.
Performance hint: If your app accesses the network or does other long-running work after receiving a location update, adjust the fastest interval to a slower value. This adjustment prevents your app from receiving updates it can't use. Once the long-running work is done, set the fastest interval back to a fast value.
Once you have connected to Google Play services and the location services
API, you can get the current location settings of a user's device. To do
this, create a
LocationSettingsRequest.Builder,
and add one or more location requests. The following code snippet shows how
to add the location request that was created in the previous step:
LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder()
.addLocationRequest(mLocationRequest);
Next check whether the current location settings are satisfied:
PendingResult<LocationSettingsResult> result =
LocationServices.SettingsApi.checkLocationSettings(mGoogleClient,
builder.build());
When the PendingResult
returns, your app can check the location settings by looking at the status
code from the LocationSettingsResult
object. To get even more details about the the current state of the relevant
location settings, your app can call the
{@code LocationSettingsResult}
object's
getLocationSettingsStates()
method.
To determine whether the location settings are appropriate for the location
request, check the status code from the
{@code LocationSettingsResult}
object. A status code of RESOLUTION_REQUIRED indicates that the
settings must be changed. To prompt the user for permission to modify the
location settings, call
{@code startResolutionForResult(Activity, int)}.
This method brings up a dialog asking for the user's permission to modify
location settings. The following code snippet shows how to check the location
settings, and how to call {@code startResolutionForResult(Activity, int)}.
result.setResultCallback(new ResultCallback<LocationSettingsResult>()) {
@Override
public void onResult(LocationSettingsResult result) {
final Status status = result.getStatus();
final LocationSettingsStates = result.getLocationSettingsStates();
switch (status.getStatusCode()) {
case LocationSettingsStatusCodes.SUCCESS:
// All location settings are satisfied. The client can
// initialize location requests here.
...
break;
case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
// Location settings are not satisfied, but this can be fixed
// by showing the user a dialog.
try {
// Show the dialog by calling startResolutionForResult(),
// and check the result in onActivityResult().
status.startResolutionForResult(
OuterClass.this,
REQUEST_CHECK_SETTINGS);
} catch (SendIntentException e) {
// Ignore the error.
}
break;
case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
// Location settings are not satisfied. However, we have no way
// to fix the settings so we won't show the dialog.
...
break;
}
}
});
The next lesson, Receiving Location Updates, shows you how to receive periodic location updates.