XAML-Map-Control/MapControl/WPF/TileImageLoader.WPF.cs

using System;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Media;

namespace MapControl
{
    public partial class TileImageLoader
    {
        private static async Task LoadTileImage(Tile tile, Func<Task<ImageSource>> loadImageFunc)
        {
            var image = await loadImageFunc().ConfigureAwait(false);

            await tile.Image.Dispatcher.InvokeAsync(() => tile.SetImageSource(image));
        }
    }
}