修改UIVIew显示圆角(指定四个角中的某个)

- (void)setViewRounded {
    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(120, 10, 80, 80)];
    view.backgroundColor = [UIColor redColor];
    [self.view addSubview:view];

    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;
    view.layer.mask = maskLayer;
}

//需要设置的指定圆角
byRoundingCorners:UIRectCornerBottomLeft | UIRectCornerBottomRight

//其他类型
* UIRectCornerTopLeft
* UIRectCornerTopRight
* UIRectCornerBottomLeft
* UIRectCornerBottomRight
* UIRectCornerAllCorners