MapTiles.Count 将为您提供将添加到列表中的下一项的索引

MapTiles.Count will give you the index of next item that will be added to the list

类似于：

Console.WriteLine("Adding " + MapTiles.Count + "th item to MapTiles List");
MapTiles.Add(new Class1(num, x * 32 + cameraX, y * 32 + cameraY));