ios - firebase 和 swift - 此类不符合 key 的键值编码 -----

Question

我知道还有其他类似的问题，但我认为我的问题是我如何访问 firebase 而不是 outlet，因为我的错误出现在 @IBAction 函数中，该函数可以在错误发生之前调用。

@IBAction func sign_in_out_tapped(sender : UIButton) {
    if let op_user = user {
        if (op_user.user_ref?.valueForKey("current_status"))! as! String == "OUT" {
            let sign_in_time = NSDate()
            op_user.user_ref?.childByAppendingPath("logins").updateChildValues([String(op_user.user_ref?.valueForKey("num_of_logins")! as! Int + 1): ["sign_in_time": sign_in_time]])
            signinout = SignInOutModel(sign_in_time: sign_in_time)

            op_user.user_ref?.updateChildValues(["current_status": "IN"])
        } else {
            signinout!.sign_out_time = NSDate()
            op_user.user_ref?.childByAppendingPath("logins").childByAppendingPath(String(user?.user_ref?.valueForKey("num_of_logins"))).updateChildValues(["sign_out_time": signinout!.sign_out_time!])

            signinout!.duration = (op_user.user_ref?.childByAppendingPath("logins").childByAppendingPath(String(user?.user_ref?.valueForKey("num_of_logins"))).valueForKey("sign_in_time")?.timeIntervalSinceNow)!
            op_user.user_ref?.childByAppendingPath("logins").childByAppendingPath(String(user?.user_ref?.valueForKey("num_of_logins"))).updateChildValues(["duration": signinout!.duration])
            op_user.user_ref?.updateChildValues(["total_hours": (Double((op_user.user_ref?.valueForKey("total_hours"))! as! NSNumber) + signinout!.duration)])
        }
} else {
        let sign_in_alert = UIAlertController(title: "Sign in.", message: "What is your first and last name?", preferredStyle: UIAlertControllerStyle.Alert)

        sign_in_alert.addTextFieldWithConfigurationHandler { textField in
            NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(MainViewController.handleTextFieldTextDidChangeNotification(_:)), name: UITextFieldTextDidChangeNotification, object: textField)
        }

        func removeTextFieldObserver() {
            NSNotificationCenter.defaultCenter().removeObserver(self, name: UITextFieldTextDidChangeNotification, object: sign_in_alert.textFields![0])
        }

        let cancel_action = UIAlertAction(title: "Cancel", style: .Cancel) { action in
            print("Sign In Cancel Button Pressed")
            removeTextFieldObserver()
        }

        let save_action = UIAlertAction(title: "Save", style: .Default) { action in
            print("Sign Out Save Button Pressed")

            let textField = sign_in_alert.textFields![0] as UITextField

            if let user_name = textField.text {
                var not_found = false

                self.students_ref.childByAppendingPath(user_name).observeEventType(.Value, withBlock: { snapshot in

                    if (snapshot.value is NSNull) {
                        not_found = true
                    } else {
                        self.user = User(user_name: user_name)
                        self.user?.user_ref = self.students_ref.childByAppendingPath(user_name)
                        self.refresh_user_name_label()
                    }
                })

                if !not_found {
                    self.mentors_ref.childByAppendingPath(user_name).observeEventType(.Value, withBlock: { snapshot in

                        if (snapshot.value is NSNull) {
                            not_found = true
                        } else {
                            self.user = User(user_name: user_name)
                            self.user?.user_ref = self.mentors_ref.childByAppendingPath(user_name)
                            self.refresh_user_name_label()
                        }
                    })
                } else {
                    self.error_message("User not found. Please update Firebase.")
                }
            } else {
                self.error_message("Could not sign in.")
            }

            removeTextFieldObserver()
        }

        save_action.enabled = false

        AddAlertSaveAction = save_action

        sign_in_alert.addAction(cancel_action)
        sign_in_alert.addAction(save_action)

        self.presentViewController(sign_in_alert, animated: true, completion: nil)

        if let _ = user {
            let sign_in_time = NSDate()
            signinout = SignInOutModel(sign_in_time: sign_in_time)
        }
    }

    refresh_sign_in_out_button()
}

我认为错误出现在顶部，上面写着“op_user.user_ref?.valueForKey("current_status"))! as String == "OUT""因为错误不仅说，

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<Firebase 0x7fa12e0b5530> valueForUndefinedKey:]: this class is not key value coding-compliant for the key current_status.'

但是当通过调试器时，程序直到“valueForKey(“current_status”)”才终止。

任何帮助将不胜感激!谢谢!

编辑:我的火力基地:

{
  "mentors" : {
    "Ash Dreyer" : {
      "current_status" : "IN",
      "num_of_logins" : 0,
      "total_hours" : 0
    },
    "Donald Pinckney" : {
      "current_status" : "OUT",
      "num_of_logins" : 0,
      "total_hours" : 0
    },
    "Jasmine Zhou" : {
      "current_status" : "OUT",
      "num_of_logins" : 0,
      "total_hours" : 0
    },
    "Michael Corsetto" : {
      "current_status" : "OUT",
      "num_of_logins" : 0,
      "total_hours" : 0
    }
  },
  "students" : {
    "Bryton Moeller" : {
      "current_status" : "OUT",
      "num_of_logins" : 0,
      "total_hours" : 0
    },
    "Kelly Ostrom" : {
      "current_status" : "OUT",
      "num_of_logins" : 0,
      "total_hours" : 0
    },
    "Kyle Stachowicz" : {
      "current_status" : "OUT",
      "num_of_logins" : 0,
      "total_hours" : 0
    },
    "Wesley Aptekar-Cassels" : {
      "current_status" : "OUT",
      "num_of_logins" : 0,
      "total_hours" : 0
    }
  }
}

编辑:

我的项目的目标是创建一个登录/注销应用程序。我的导师希望其他人能够看到某人是否已登录，并希望跟踪某人总共登录了多长时间(比如他们是否已经在商店里工作了 100 个小时之类的。)

Answer 1

您的问题是您尝试访问 Firebase 引用数据的方式。 valueForKey 不是正确的方法。您需要执行以下两项操作之一:

1. 首先将您的 firebaseSnap.value 转换为字典，然后使用 dict[key] 语法。
2. Snapshot.childSnapshotForPath("current_status").value

我推荐第 2 种方法，因为它是最简洁的方法。但是，如果您需要经常访问引用，您可能希望转换为字典，因为那样访问它看起来会更好。

注意:这两个都需要一个 firebase 事件监听器来获取 firebase 快照。

如果您有任何问题，请告诉我，祝您好运!