从Facebook获取用户生日

Question

这是我的代码，但我无法获得用户生日我收到的所有内容除了用户生日请帮助获得用户生日

if (FBSession.activeSession.isOpen) {
  [FBRequestConnection startWithGraphPath: @"me"
    parameters: [NSDictionary dictionaryWithObject: @"email,first_name,last_name,picture,birthday,gender,age_range,name"
      forKey: @"fields"
    ]
    HTTPMethod: @"GET"
    completionHandler: ^ (FBRequestConnection * connection, id result, NSError * error) {
      if (!error) {
        [MBProgressHUD showHUDAddedTo: self.view animated: YES];

        // result is a dictionary with the user's Facebook data
        userData = (NSDictionary * ) result;
      }
    }