视图圆角设置

//以一个UIView为例

UIView *view = [[UIView alloc] init];
view.frame = CGRectMake(100, 100, 100, 100);
view.backgroundColor = [UIColor purpleColor];
[self.view addSubview:view];

1.这种情况是4个角全部设置

view.layer.cornerRadius = 10;
view.layer.masksToBounds = YES;

2.这种情况是选择哪几个角进行设置

//设置哪几个圆角主要取决于byRoundingCorners的设置

//UIRectCornerTopLeft 左上

//UIRectCornerTopRight 右上

//UIRectCornerBottomLeft 左下

//UIRectCornerBottomRight 右下

//UIRectCornerAllCorners 所有

//组合使用各个值之间用“|”连接，前四个值全设置相当于只设置UIRectCornerAllCorners的效果

//cornerRadii的设置取决于size中的width值

UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds byRoundingCorners:UIRectCornerTopLeft | UIRectCornerTopRight | UIRectCornerBottomLeft cornerRadii:CGSizeMake(10, 0)];
CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
maskLayer.frame = view.bounds;
maskLayer.path = maskPath.CGPath;
view.layer.mask = maskLayer;