UIImageView上添加Button不能响应点击事件

UIImageView *backImageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, self.view.frame.size.height-UITABBAR_HEIGHT-216-39, 320, 43) ];

[backImageView setUserInteractionEnabled:YES];//使添加其上的button有点击事件

[backImageView setImage:[UIImage imageNamed:@"navigationBar.png"]];

[backScroll addSubview:backImageView];

UIButton *loginButton = [UIButton alloc];

[loginButton setFrame:CGRectMake(10, 0, 40, 43)];

[loginButton setTitle:@"hello" forState:UIControlStateNormal];

[loginButton addTarget:self action:@selector(loginOrLogout) forControlEvents:UIControlEventTouchUpInside];

[backImageView addSubview:loginButton];

来源：http://blog.sina.com.cn/s/blog_9c3c519b0100yhfh.html