//1.创建图片    _userImage = [[UIImageView alloc]init];　　
　　//2.设置图片圆角    _userImage.layer.cornerRadius  = 33;    _userImage.layer.masksToBounds = YES;        //3.设置圆形边框    CALayer *layer    = [_userImage layer];    layer.borderColor = [[UIColor whiteColor] CGColor];    layer.borderWidth = 2.0f;        //4.给图片添加点击事件    _userImage.userInteractionEnabled    = YES;    UITapGestureRecognizer *userImageTap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(userImageAction)];    [_userImage addGestureRecognizer: userImageTap];