iOS - 设置圆角

    UIImage * image = [UIImage imageNamed:@"1"];
    //方式一： 设置layer属性
    UIImageView *imageView1 = [[UIImageView alloc ] initWithFrame:CGRectMake(100, 100, 100, 100)];
    [imageView1 setImage:image];
    //设置圆角大小
    imageView1.layer.cornerRadius = 20;
    //masksToBounds 默认是NO，需要设置成YES，将视图的图层上的子图层超出部分截取掉。
    imageView1.layer.masksToBounds = YES;
    [self.view addSubview:imageView1];

    //方法二：使用贝塞尔曲线UIBezierPath和Core Graphics框架画出一个圆角
    UIImageView *imageView2 = [[UIImageView alloc] initWithFrame:CGRectMake(100, 220, 100, 100)];
    [imageView2 setImage:image];

    UIGraphicsBeginImageContextWithOptions(imageView2.bounds.size, NO, [UIScreen mainScreen].scale);
    [[UIBezierPath bezierPathWithRoundedRect:imageView2.bounds cornerRadius:20] addClip];
    [imageView2 drawRect:imageView2.bounds];
    imageView2.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    [self.view addSubview:imageView2];

    //方法三：使用CAShapeLayer和UIBezierPath设置圆角
    UIImageView *imageView3 = [[UIImageView alloc] initWithFrame:CGRectMake(100, 330, 100, 100)];
    [imageView3 setImage:image];
    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:imageView3.bounds byRoundingCorners:UIRectCornerAllCorners cornerRadii:CGSizeMake(20,20)];
    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
    maskLayer.frame = imageView3.bounds;
    maskLayer.path = maskPath.CGPath;
    imageView3.layer.mask = maskLayer;
    [self.view addSubview:imageView3];