Xamarin iOS - CLLocationManager 在后台以设定的时间间隔获取位置

Question

我正在尝试向我的应用程序添加一项功能，该功能需要在设定的时间间隔内获取用户的当前位置。问题是每当我使用 System.Threading.Timer、创建新的 System.Threading.Thread 并使用 Thread.Sleep() 或使用 NSTimer.CreateScheduledTimer 时，应用程序都会停止 CLLocationManager 来自 [=24] =]当应用程序在后台运行时。

LocationManager.cs

public class LocationManager
{
    protected CLLocationManager locationManager;
    /// <summary>
    /// Time in milliseconds between location checking.
    /// </summary>
    private int serviceMillisecondTimeout = 10000;

    public LocationManager()
    {
        this.locationManager = new CLLocationManager();

        // iOS 8 additional permissions requirements
        if (UIDevice.CurrentDevice.CheckSystemVersion(8, 0))
        {
            locationManager.RequestAlwaysAuthorization();
        }

        locationManager.LocationsUpdated += onLocationUpdated;
        locationManager.DistanceFilter = 1;
        locationManager.DesiredAccuracy = 1;
    }

    public CLLocationManager LManager
    {
        get { return locationManager; }
    }

    public void startLocationUpdates()
    {
        if (CLLocationManager.LocationServicesEnabled)
        {
            locationManager.StartUpdatingLocation();
        }
    }

    public void stopLocationUpdates()
    {
        locationManager.StopUpdatingLocation();
    }

    public void onLocationUpdated(object sender, CLLocationsUpdatedEventArgs e)
    {
        // stop location updates until timer calls StartUpdatingLocation
        locationManager.StopUpdatingLocation();

        var coordinate = e.Locations[e.Locations.Length - 1].Coordinate;
        double lat = coordinate.Latitude;
        double lon = coordinate.Longitude;

        // do stuff with coordinates

        // This will work until the application goes into the background.
        // The same thing seems to happen whenever I try creating
        // new threads, or any other form of a timer.
        //
        // Without any sort of timer or new thread, it will call
        // StartUpdatingLocation in the background and will
        // continue to run indefinitely.
        NSTimer t = NSTimer.CreateScheduledTimer(TimeSpan.FromMilliseconds(serviceMillisecondTimeout), delegate
        {
            if (CLLocationManager.LocationServicesEnabled)
            {
                locationManager.StartUpdatingLocation();
            }
        });
    }
}

如何才能设置明确的时间间隔并仍然能够在后台运行位置更新？

Answer 1

平台不支持此功能。您可以在后台或离开设置的地理围栏时订阅重要的位置更改，但您不能强制您的代码在后台以特定时间间隔获取位置修复。这是 iOS 平台的 restriction/limitation，您对此无能为力。

最接近您想要的可能是 Getting Location Events in the Background。

Xamarin iOS - CLLocationManager 在后台以设定的时间间隔获取位置

Xamarin iOS - CLLocationManager get location at set time interval while in background

location

background

geolocation

ios

xamarin