1 /* 2 3 NSObject -> CALayer ->CAShapeLayer(CAGradientLayer) 4 5 NSObject -> UIImage 6 7 NSObject -> UIResponder -> UIView -> UIScrollView -> UITableView(UICollectionView) 8 9 NSObject -> UIResponder -> UIView -> UIControl -> UIButton 10 11 */
原文：http://www.cnblogs.com/panda1024/p/6339998.html