一个button或者label，只要右边的两个角圆角，或者只要一个圆角。该怎么办呢？这就需要图层蒙版来帮助我们了

 

CGRect rect = CGRectMake(0, 0, 100, 50);

CGSize radio = CGSizeMake(5, 5);//圆角尺寸

UIRectCorner corner = UIRectCornerTopLeft|UIRectCornerTopRight;//这只圆角位置

UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:corner cornerRadii:radio];

CAShapeLayer *masklayer = [[CAShapeLayer alloc]init];//创建shapelayer

masklayer.frame = button.bounds;

masklayer.path = path.CGPath;//设置路径

button.layer.mask = masklayer;