如果达到某个分数，请添加Sprite

I have a simple game. You start with a ball and you bounce it until you get 10 points. When you reach 10 points, another ball appears(so that reaching the next landmark can be faster). When 20 points is reached, a third ball appears. I have this already set up, but I need to know how to do an I have a simple game. You start with a ball and