为什么以下值未插入Firebase数据库中？

Question

为什么以下值未正确存储：

["firstname": self.firstNameField.text, "lastname": self.lastNameField.text, "email": self.emailField.text, "city": self.cityField.text, "telnumber": self.telNumField.text]

用户的电子邮件和密码正确注册，但电话，电子邮件，城市值未存储。

我在以下行中遇到错误：

usersReference.updateChildValues(values, withCompletionBlock: { (err, ref)

错误提示：

表达式从'[String：String？]'隐式强制为'[AnyHashable：Any]'

以下是我的代码：

import UIKit
import Firebase
import FirebaseAuth

class RegisterViewController: UIViewController {

private var ref: DatabaseReference! // референс к БД

@IBOutlet weak var emailField: UITextField!
@IBOutlet weak var passwordField: UITextField!
@IBOutlet weak var firstNameField: UITextField!
@IBOutlet weak var lastNameField: UITextField!
@IBOutlet weak var cityField: UITextField!
@IBOutlet weak var telNumField: UITextField!


override func viewDidLoad() {
    super.viewDidLoad()

    ref = Database.database().reference() // инициализация БД

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()

}

@IBAction func nextButtonPressed(_ sender: Any) {
    Auth.auth().createUser(withEmail: self.emailField.text!, password: self.passwordField.text!) { (user, error) in

        if error != nil {
            print(error!)
            self.showAlert(title: "Error!", msg: "Invalid information", actions: nil)
            return
        }
        print("Registration succesfull")

        guard let uid = user?.uid else { //доступ к ID пользователя
            return
        }

        self.ref = Database.database().reference() // инициализация БД
        let usersReference = self.ref.child("users").child(uid)
        let values = ["firstname": self.firstNameField.text, "lastname": self.lastNameField.text, "email": self.emailField.text, "city": self.cityField.text, "telnumber": self.telNumField.text]
        usersReference.updateChildValues(values, withCompletionBlock: { (err, ref) in
            if let err = err {
                print(err)
                return
            }
            print("Saved user successfully into Firebase db")
        })
    }
}

private func showAlert(title: String, msg: String, actions:[UIAlertAction]?) {

    var actions = actions
    let alertVC = UIAlertController(title: title, message: msg, preferredStyle: .alert)

    if actions == nil {
        actions = [UIAlertAction(title: "OK", style: .default, handler: nil)]
    }

    for action in actions! {
        alertVC.addAction(action)
    }

    if let rootVC = UIApplication.shared.delegate?.window??.rootViewController {
        rootVC.present(alertVC, animated: true, completion: nil)
    } else {
        print("Root view controller is not set.")
    }
}


// outside keyboard
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    self.view.endEditing(true)
}

}