Return the location data from GeoCoordinateWatcher.StatusChanged event in Windows Phone 7

问题

I'm writing a Windows Phone app where I need to get user's location. I'm trying to this in a nice way (well as much as I can), using a separate class where I'm querying GeoCoordinateWatcher for location data and return that data to calling method.

The problem is, I don't know how to return the the LocationData struct to the calling method from the StatusChanged event of the GeoCoordinateWatcher. See the code & comments:

public struct LocationData
{
    public string latitude;
    public string longitude;
}


public class LocationService : GeoCoordinateWatcher
{
    private GeoCoordinateWatcher watcher;

    private LocationData StartLocationWatcher()
    {
        LocationData ld = new LocationData();

        // The watcher variable was previously declared as type GeoCoordinateWatcher.
        if (watcher == null)
        {
            watcher = new GeoCoordinateWatcher(GeoPositionAccuracy.High);
        }

        watcher.MovementThreshold = 20; // Use MovementThreshold to ignore noise in the signal.

        watcher.StatusChanged += (o, args) =>
            {
                switch (args.Status)
                {
                    case GeoPositionStatus.Ready:
                       // Use the Position property of the GeoCoordinateWatcher object to get the current location.
                       GeoCoordinate co = watcher.Position.Location;

                       ld.latitude = co.Latitude.ToString("0.000");
                       ld.longitude = co.Longitude.ToString("0.000");

                       //Stop the Location Service to conserve battery power.

                       watcher.Stop();
                       break;
               }
           };

        watcher.Start();
        return ld; //need to return this to the calling method, with latitude and longitude data taken from GeoCoordinateWatcher
    }
}

回答1:

I'm not sure if this is what you're after.

you have to add an event listener to fire the fetching of the location

GeoCoordinateWatcher.PositionChanged += GeoCoordinateWatcherPositionChanged;

private void GeoCoordinateWatcherPositionChanged(object sender, GeoPositionChangedEventArgs<GeoCoordinate> e)
{
    var currentLatitude = e.Position.Location.Latitude;
    var currentLongitude = e.Position.Location.Longitude;
}