设置指定某个角为圆角

UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view2.bounds byRoundingCorners:UIRectCornerBottomLeft | UIRectCornerBottomRight cornerRadii:CGSizeMake(10, 10)];
CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
maskLayer.frame = view2.bounds;maskLayer.path = maskPath.CGPath;
view2.layer.mask = maskLayer;

指定角参数是

* UIRectCornerTopLeft
* UIRectCornerTopRight
* UIRectCornerBottomLeft
* UIRectCornerBottomRight
* UIRectCornerAllCorners
//用“|”分隔开