iOS - view部分圆角

view的右上角及右下角添加圆角：

    UIBezierPath *maskPath2 = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, ScreenWidth - 15, self.warnView.height)    byRoundingCorners:UIRectCornerBottomRight | UIRectCornerTopRight    cornerRadii:CGSizeMake(self.warnView.height/2.0, self.warnView.height/2.0)];
    CAShapeLayer *maskLayer2 = [[CAShapeLayer alloc] init];
    maskLayer2.frame = CGRectMake(0, 0, ScreenWidth - 15, self.warnView.height);
    maskLayer2.path = maskPath2.CGPath;
    self.warnView.layer.mask = maskLayer2;