Respond to location updates (XAML)
Learn how to receive updates of the user's location over a period of time. This topic uses code examples, based on the geolocation sample, to demonstrate key points. For more info, download and run the sample.
Roadmap: How does this topic relate to others? See:
Step 1: Verify that location is enabled
Before your app can access location, Location must be enabled on the device. In the Settings app, check that the following location privacy settings are turned on:
- Location for this device... is turned on (not applicable in Windows 10 Mobile)
- The location services setting, Location, is turned on
- Under Choose apps that can use your location, your app is set to on
Step 2: Enable the location capability
Double click on package.appxmanifest in Solution Explorer and select the Capabilities tab. Then check Location in the Capabilities list. This adds the Location device capability to the package manifest file.
<Capabilities>
<!-- DeviceCapability elements must follow Capability elements (if present) -->
<DeviceCapability Name="location"/>
</Capabilities>
Step 3: Request access to the user's location
Request access to the user's location using the RequestAccessAsync method.
Important Starting in Windows 10, call the RequestAccessAsync before accessing the user’s location. At that time, your app must be in the foreground and RequestAccessAsync must be called from the UI thread. Until the user grants your app permission to their location, your app can't access location data.
using Windows.Devices.Geolocation;
...
var accessStatus = await Geolocator.RequestAccessAsync();
The RequestAccessAsync method prompts the user for permission to access their location. The user is only prompted once (per app). After the first time they grant or deny permission, this method no longer prompts for permission. To help the user change location permissions after they've been prompted, we recommend providing a link to the location settings as demonstrated later in this topic.
Step 4: Define the report interval and register for location updates
In this example, a switch statement is used with accessStatus (from the previous example) to act only when access to location is allowed. If allowed, the code creates a Geolocator object, specifies the tracking type, and registers for location updates.
The Geolocator object can trigger the PositionChanged event based on a change in position (distance-based tracking) or a change in time (periodic-based tracking). For distance-based tracking, set the MovementThreshold property. For periodic-based tracking, set the ReportInterval. If neither are set, a position will be returned every 1 second (equivalent to ReportInterval = 1000). Here, a 2 second report interval is used.
switch (accessStatus)
{
case GeolocationAccessStatus.Allowed:
// Create Geolocator and define perodic-based tracking (2 second interval)
_geolocator = new Geolocator { ReportInterval = 2000 };
// Subscribe to PositionChanged event to get location updates
_geolocator.PositionChanged += OnPositionChanged;
// Subscribe to StatusChanged event to get updates of location status changes
_geolocator.StatusChanged += OnStatusChanged;
_rootPage.NotifyUser("Waiting for update...", NotifyType.StatusMessage);
LocationDisabledMessage.Visibility = Visibility.Collapsed;
StartTrackingButton.IsEnabled = false;
StopTrackingButton.IsEnabled = true;
break;
case GeolocationAccessStatus.Denied:
_rootPage.NotifyUser("Access to location is denied.", NotifyType.ErrorMessage);
LocationDisabledMessage.Visibility = Visibility.Visible;
break;
case GeolocationAccessStatus.Unspecified:
_rootPage.NotifyUser("Unspecificed error!", NotifyType.ErrorMessage);
LocationDisabledMessage.Visibility = Visibility.Collapsed;
break;
}
Step 5: Handle location updates
The Geolocator object triggers the PositionChanged event to indicate that the user's location changed or time has passed, depending on how you've configured it. That event passes the corresponding location via the argument's Position property (of type Geoposition). In this example, the method is not called from the UI thread and the Dispatcher object invokes the UI changes.
using Windows.UI.Core;
...
async private void OnPositionChanged(Geolocator sender, PositionChangedEventArgs e)
{
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
_rootPage.NotifyUser("Location updated.", NotifyType.StatusMessage);
UpdateLocationData(e.Position);
});
}
Step 6: Handle changes in location permissions
The Geolocator object triggers the StatusChanged event to indicate that the user's location settings changed. That event passes the corresponding status via the argument's Status property (of type PositionStatus). Once again, the method is not called from the UI thread and the Dispatcher object invokes the UI changes.
using Windows.UI.Core;
...
async private void OnStatusChanged(Geolocator sender, StatusChangedEventArgs e)
{
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
// Show the location setting message only if status is disabled.
LocationDisabledMessage.Visibility = Visibility.Collapsed;
switch (e.Status)
{
case PositionStatus.Ready:
// Location platform is providing valid data.
ScenarioOutput_Status.Text = "Ready";
_rootPage.NotifyUser("Location platform is ready.", NotifyType.StatusMessage);
break;
case PositionStatus.Initializing:
// Location platform is attempting to acquire a fix.
ScenarioOutput_Status.Text = "Initializing";
_rootPage.NotifyUser("Location platform is attempting to obtain a position.", NotifyType.StatusMessage);
break;
case PositionStatus.NoData:
// Location platform could not obtain location data.
ScenarioOutput_Status.Text = "No data";
_rootPage.NotifyUser("Not able to determine the location.", NotifyType.ErrorMessage);
break;
case PositionStatus.Disabled:
// The permission to access location data is denied by the user or other policies.
ScenarioOutput_Status.Text = "Disabled";
_rootPage.NotifyUser("Access to location is denied.", NotifyType.ErrorMessage);
// Show message to the user to go to location settings
LocationDisabledMessage.Visibility = Visibility.Visible;
// Clear cached location data if any
UpdateLocationData(null);
break;
case PositionStatus.NotInitialized:
// The location platform is not initialized. This indicates that the application
// has not made a request for location data.
ScenarioOutput_Status.Text = "Not initialized";
_rootPage.NotifyUser("No request for location is made yet.", NotifyType.StatusMessage);
break;
case PositionStatus.NotAvailable:
// The location platform is not available on this version of the OS.
ScenarioOutput_Status.Text = "Not available";
_rootPage.NotifyUser("Location is not available on this version of the OS.", NotifyType.ErrorMessage);
break;
default:
ScenarioOutput_Status.Text = "Unknown";
_rootPage.NotifyUser(string.Empty, NotifyType.StatusMessage);
break;
}
});
}
Step 7: Help the user change location settings
If the location settings don't allow your app to access the user's location, we recommend providing a convenient link to the location privacy settings in the Settings app. In this example, a Hyperlink control is used navigate to the ms-settings:privacy-location URI.
<!--Set Visibility to Visible when access to location is denied -->
<TextBlock x:Name="LocationDisabledMessage" FontStyle="Italic"
Visibility="Collapsed" Margin="0,15,0,0" TextWrapping="Wrap" >
<Run Text="This app is not able to access Location. Go to " />
<Hyperlink NavigateUri="ms-settings:privacy-location">
<Run Text="Settings" />
</Hyperlink>
<Run Text=" to check the location privacy settings."/>
</TextBlock>
Alternatively, your app can call the LaunchUriAsync method to launch the Settings app from code. For more info, see How to launch the Settings app.
using Windows.System;
...
bool result = await Launcher.LaunchUriAsync(new Uri("ms-settings:privacy-location"));