How to save and append to a map layer?

问题:

I have a method to draw pushpins to a map which works fine, but I need to append a second pushpin to the first layer. I'm guessing this will involve saving the first layer so that it can be manipulated later. Does anyone have any idea how I would go about this as I'm not quite sure how to save a layer?

At present the DrawPushPin method is called twice in the app, so the first time a new layer is created and same for the second time but this is not ideal as I need to append to the first layer not create a new one.

The method is called like this DrawPushPinCurrent(MyGeoPosition, pushPinName); and below is the draw method.

private void DrawPushPin(GeoCoordinate MyGeoPosition,string pushPinName)
        {
            MapLayer layer1 = new MapLayer();
            Pushpin pushpin1 = new Pushpin();

            pushpin1.GeoCoordinate = MyGeoPosition;
            pushpin1.Content = pushPinName;


            MapOverlay overlay1 = new MapOverlay();
            overlay1.Content = pushpin1;
            overlay1.GeoCoordinate = MyGeoPosition;
            layer1.Add(overlay1);

            MyMap.Layers.Add(layer1);
            MyMap.Center = MyGeoPosition;
            MyMap.ZoomLevel = 15;


        }

回答1:

What I would do is move the MapLayer outside of the method and make them global (at the class level). Then I would create another method like this:

MapLayer layer1;

public MyClass()
{
   layer1 = new MapLayer;
}

private void AppendPushpin(GeoCoordinate MyGeoPosition, string pushpinName)
{
   Pushpin pushpin1 = new Pushpin();

   pushpin1.GeoCoordinate = MyGeoPosition;
   pushpin1.Content = pushPinName;

   MapOverlay overlay1 = new MapOverlay();
   overlay1.Content = pushpin1;
   overlay1.GeoCoordinate = MyGeoPosition;
   layer1.Add(overlay1);
}

*EDIT

In your case, where you need to store that variable application-wide, you would want to persist that MapLayer object doing something like this:

Windows.Storage.ApplicationDataContainer localSettings =   Windows.Storage.ApplicationData.Current.LocalSettings;
localSettings.Values["MapLayer"] = layer1;

Its up to you on where you need to set and get this global variable.