如何实现聊天软件的图片显示的剪裁后的气泡呢  

Objective-C:  

- (void)viewDidLoad {    [super viewDidLoad];        UIImageView *ImageView01 = [[UIImageView alloc] init];    [ImageView01 setFrame:CGRectMake(90, 190, 120, 180)];    [ImageView01 setImage:[UIImage imageNamed:@"style.jpg"]];    [self.view addSubview:ImageView01];        UIImage *bubble = [UIImage imageNamed:@"icon_chat_right_bg"];    UIImageView *ImageView = [[UIImageView alloc] init];    [ImageView setFrame:ImageView01.frame];    [ImageView setImage:[bubble stretchableImageWithLeftCapWidth:15 topCapHeight:15]];        CALayer *layer              = ImageView.layer;    layer.frame                 = (CGRect){
    {0,0},ImageView.layer.frame.size};    ImageView01.layer.mask = layer;    [ImageView01 setNeedsDisplay];}

Swift:

    override func viewDidLoad() {        super.viewDidLoad()        // Do any additional setup after loading the view, typically from a nib.        var imageview01 = UIImageView(frame: CGRectMake(90, 190, 120, 180))        imageview01.image = UIImage(named: "style.jpg")        self.view.addSubview(imageview01)                var imageview02 = UIImageView(frame: imageview01.frame)        imageview02.image = UIImage(named: "icon_chat_right_bg")?.stretchableImageWithLeftCapWidth(15, topCapHeight: 15)                var layer = imageview02.layer        layer.frame = CGRect(origin: CGPointZero,size: imageview02.layer.frame.size)        imageview01.layer.mask = layer            }

style.jpg:  

:  

icon_chat_right_bg: