ios关于图片拉伸的版本间的几种方法
1.iOS 5.0之前的做法 - (UIImage *)stretchableImageWithLeftCapWidth:(NSInteger)leftCapWidth topCapHeight:(NSInteger)topCapHeight; 2.iOS 5.0的做法 - (UIImage *)resizableImageWithCapInsets:(UIEdgeInsets)capInsets; 3.iOS 6.0的做法 - (UIImage *)resizableImageWithCapInsets:(UIEdgeInsets)capInsets resizingMode:(UIImageResizingMode)resizingMode;