如何让阴影和圆角同时实现 | iOS开发

                                                    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];

    button.layer.shadowRadius = 5;
    button.layer.cornerRadius = 25 ;
    button.layer.shadowColor = [UIColor redColor].CGColor;
    button.layer.shadowOffset = CGSizeMake(13,13);
//    button.layer.masksToBounds = YES;

注释掉的masksToBounds设为YES就没有阴影，设为NO就没有圆角