图片复用、内容拉升

1、- (UIImage *)resizableImageWithCapInsets:(UIEdgeInsets)capInsets resizingMode:(UIImageResizingMode)resizingMode NS_AVAILABLE_IOS(6_0); // the interior is resized according to the resizingMode

复用某个区域 

typedef NS_ENUM(NSInteger, UIImageResizingMode) {

    UIImageResizingModeTile,

    UIImageResizingModeStretch,

};

由文档 可知，一个是 填充 一个 是拉伸.

2、- (UIImage *)stretchableImageWithLeftCapWidth:(NSInteger)leftCapWidth topCapHeight:(NSInteger)topCapHeight;

 从某点开始复用

使用：

//   UIImage* img = [[UIImage imageNamed:@"bg"] stretchableImageWithLeftCapWidth:80 topCapHeight:20];

    UIImage* img =[[UIImage imageNamed:@"bg"] resizableImageWithCapInsets:UIEdgeInsetsMake(20, 80, 20, 10) resizingMode:UIImageResizingModeTile];

    UIImageView* imageV = [[UIImageView alloc] initWithFrame:CGRectMake(0, 200, 300, 200)];

    imageV.image = img;

    [self.view addSubview:imageV];