Geolocation plugin for Xamarin and Windows
In addition to a one shot location query you can easily register for location changes. By default these are for foreground changes when your application is open. For background or when app is closed be srue to read through the Background Updates documentation.
Before subscribing to events you must start listening, which will start the managers to query for location changes.
To check to see if you are listning there is a nifty IsListening property on the CrossGeolocator.Current that you can use.
/// <summary>
/// Gets if you are listening for location changes
/// </summary>
bool IsListening { get; }
Once you are ready to start listening for changes you can call the StartListeningAsync. After this, you can add event handlers to get the changes.
/// <summary>
/// Start listening for changes
/// </summary>
/// <param name="minimumTime">Minimum time between updates</param>
/// <param name="minimumDistance">Distance distance in meters between updates</param>
/// <param name="includeHeading">Include heading or not</param>
/// <param name="listenerSettings">Optional settings (iOS only)</param>
Task<bool> StartListeningAsync(TimeSpan minimumTime, double minimumDistance, bool includeHeading = false, ListenerSettings listenerSettings = null);
ListenerSettings are details more in the Background Updates documentation.
UWP Note: How the Geolocator works you must either set the minTime or the minDistance. Setting both means that minDistance will take precedence between the two. You can read more on the Windows blog.
/// <summary>
/// Position changed event handler
/// </summary>
event EventHandler<PositionEventArgs> PositionChanged;
These event args have one property of Position that is the new position that has been detected.
If an error occures you will be notified by this event. It is best practice to stop listening and start listening again after handling the error.
/// <summary>
/// Position error event handler
/// </summary>
event EventHandler<PositionErrorEventArgs> PositionError;
When you are all done you can stop listening for changes.
/// <summary>
/// Stop listening
/// </summary>
/// <returns>If successfully stopped</returns>
Task<bool> StopListeningAsync();
Example:
async Task StartListening()
{
if(CrossGeolocator.Current.IsListening)
return;
await CrossGeolocator.Current.StartListeningAsync(TimeSpan.FromSeconds(5), 10, true);
CrossGeolocator.Current.PositionChanged += PositionChanged;
CrossGeolocator.Current.PositionError += PositionError;
}
private void PositionChanged(object sender, PositionEventArgs e)
{
//If updating the UI, ensure you invoke on main thread
var position = e.Position;
var output = "Full: Lat: " + position.Latitude + " Long: " + position.Longitude;
output += "\n" + $"Time: {position.Timestamp}";
output += "\n" + $"Heading: {position.Heading}";
output += "\n" + $"Speed: {position.Speed}";
output += "\n" + $"Accuracy: {position.Accuracy}";
output += "\n" + $"Altitude: {position.Altitude}";
output += "\n" + $"Altitude Accuracy: {position.AltitudeAccuracy}";
Debug.WriteLine(output);
}
private void PositionError(object sender, PositionErrorEventArgs e)
{
Debug.WriteLine(e.Error);
//Handle event here for errors
}
async Task StopListening()
{
if(!CrossGeolocator.Current.IsListening)
return;
await CrossGeolocator.Current.StopListening);
CrossGeolocator.Current.PositionChanged -= PositionChanged;
CrossGeolocator.Current.PositionError -= PositionError;
}
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