public override void RequestTile(nuint x, nuint y, nuint zoom, ITileReceiver receiver)
 {
     _tileImageAsync((int)x, (int)y, (int)zoom).ContinueWith((Task <byte[]> task) =>
     {
         var imgByte = task.Result;
         var image   = new UIImage(NSData.FromArray(imgByte));
         receiver.ReceiveTile(x, y, zoom, image);
     });
 }
 public override void RequestTile(nuint x, nuint y, nuint zoom, ITileReceiver receiver)
 {
     _tileImageAsync((int)x, (int)y, (int)zoom).ContinueWith((Task<byte[]> task) =>
     {
         var imgByte = task.Result;
         var image = new UIImage(NSData.FromArray(imgByte));
         receiver.ReceiveTile(x, y, zoom, image);
     });
 }