设置UIView四个角中任意角的圆角效果

UIView *view = [[UIView alloc] initWithFrame:CGRectMake(120, 10, 80, 80)];

view.backgroundColor = [UIColor redColor];

[self.view addSubview:view];

UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds byRoundingCorners:UIRectCornerBottomLeft | UIRectCornerBottomRight cornerRadii:CGSizeMake(10, 10)];

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

maskLayer.frame = view.bounds;

maskLayer.path = maskPath.CGPath;

view.layer.mask = maskLayer;

有枚举来指定了需要成为圆角的角。该参数是UIRectCorner类型的，可选的值有：

* UIRectCornerTopLeft

* UIRectCornerTopRight

* UIRectCornerBottomLeft

* UIRectCornerBottomRight

* UIRectCornerAllCorners