IOS UITapGestureRecognizer 遇到父view添加UIImageView的背景图片，子subview的tap事件不起作用了

问题：遇到父view添加UIImageView的背景图片，子subview的tap事件不起作用了

解决办法：

父view的UIImageView添加

headerImageView.userInteractionEnabled = YES;

详细代码：

        UIImageView *headerImageView = nil;

        headerImageView = [[UIImageView alloc] initWithFrame: CGRectMake(0, 0, headerView.frame.size.width, headerHeight-30)];//2015/12/30

        NSLog(@"headerImageView.W = %f and headerImageView.H = %f",headerView.frame.size.width,headerHeight);

        UIImage *image = nil;

        if (image == nil) {

            image = [UIImage imageNamed:@"icon_personal_banner.png"];

        }

        headerImageView.image = image;

        headerImageView.userInteractionEnabled = YES;

        

        

        UIImageView *avatarImageView = [[UIImageView alloc] initWithFrame: CGRectMake(headerImageView.frame.size.width - 70, headerHeight - 63, 60, 60)];

        UIImage *avatarImage = [FunctionTools getAvatarByFileName: self.friendId];

        if (avatarImage == nil) {

            avatarImage = [UIImage imageNamed:@"default_header_image"];

        }

        avatarImageView.layer.cornerRadius = CGRectGetHeight(avatarImageView.frame)/2.0;

        avatarImageView.layer.masksToBounds = YES;

        avatarImageView.image = avatarImage;

        [headerImageView addSubview: avatarImageView];

        avatarImageView.userInteractionEnabled = YES;

        UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(touchHeaderImageView:)];

        [avatarImageView addGestureRecognizer: tap];