我无法让我的球SKSpriteNode显示在辅助View Controller的UIImage（Xcode / Swift 2）上

I have a button on my first view controller that leads to the second view controller. When the second view controller appears, a ball image is supposed to appear and it's code is supposed to run. I seem to be having a little bit of trouble figuring out why the image isn't appearing. Any help would be greatly appreciated!I have a button on my first view controller tha