iOS之给button加边框 . 圆角弧度 . 加阴影

avatarImage = [UIButton buttonWithType:UIButtonTypeCustom];
        //给按钮加一个白色的板框
        avatarImage.layer.borderColor = [[UIColor whiteColor] CGColor];
        avatarImage.layer.borderWidth = 1.0f;
        //给按钮设置弧度,这里将按钮变成了圆形
        avatarImage.layer.cornerRadius = 25.0f;
        avatarImage.backgroundColor = [UIColor redColor];
        avatarImage.layer.masksToBounds = YES;