iOS 设置UIView的某个角圆角

1、设置四个角为同一弧度的圆角

UIView *cornerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 120, 10)];
cornerView.backgroundColor = [UIColor whiteColor];
cornerView.layer.masksToBounds = YES;
cornerView.layer.cornerRadius = 8;
[self addSubview:cornerView];

2、设置某个角为圆角

UIRectCornerTopLeft  //上部左角
UIRectCornerTopRight  //上部右角
UIRectCornerBottomLeft  //下部左角
UIRectCornerBottomRight //下部右角
UIRectCornerAllCorners  // 设置所有的角
可以通过 “|” 组合使用

UIView *cornerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0,  120, 10)];
cornerView.backgroundColor = [UIColor redColor];
[self addSubview:cornerView];

UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:cornerView.bounds byRoundingCorners:UIRectCornerTopLeft | UIRectCornerTopRight cornerRadii:CGSizeMake(8, 8)];
CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
maskLayer.frame = cornerView.bounds;
maskLayer.path = maskPath.CGPath;
cornerView.layer.mask = maskLayer;