1.通过设置layer的属性

最简单的一种,但是很影响性能,一般在正常的开发中使用很少.

UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(100, 100, 100, 100)]; //只需要设置layer层的两个属性

//设置圆角 imageView.layer.cornerRadius = imageView.frame.size.width / 2;

//将多余的部分切掉 imageView.layer.masksToBounds = YES;

[self.view addSubview:imageView];

2.使用贝塞尔曲线UIBezierPath和Core Graphics框架画出一个圆角

UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(100, 100, 100, 100)];

imageView.image = [UIImage imageNamed:@"1"];

//开始对imageView进行画图 UIGraphicsBeginImageContextWithOptions(imageView.bounds.size, NO, 1.0);

//使用贝塞尔曲线画出一个圆形图 [[UIBezierPath bezierPathWithRoundedRect:imageView.bounds cornerRadius:imageView.frame.size.width] addClip];

[imageView drawRect:imageView.bounds];

imageView.image = UIGraphicsGetImageFromCurrentImageContext();

//结束画图

UIGraphicsEndImageContext();

[self.view addSubview:imageView];

3.使用CAShapeLayer和UIBezierPath设置圆角

 UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(100, 100, 100, 100)];

imageView.image = [UIImage imageNamed:@"1"];

UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:imageView.bounds byRoundingCorners:UIRectCornerTopLeft | UIRectCornerBottomRight cornerRadii:imageView.bounds.size];

CAShapeLayer *maskLayer = [[CAShapeLayer alloc]init];

//设置大小

maskLayer.frame = imageView.bounds;

//设置形状

maskLayer.path = maskPath.CGPath;

imageView.layer.mask = maskLayer;

[self.view addSubview:imageView]; }

这三种方法中第三种最好，对内存的消耗最少啊，而且渲染快速。