ios - 注册时发生错误处理

Question

当我尝试 else 语句时，代码会停止并给出此错误“使用未解析的标识符‘错误’”。我该如何修复它并仍然有 UIAlert？

        @IBAction func registerTapped(_ sender: Any) {
        print("tapped")
        let namec = nameTextField.text
        if let email = emailTextField.text, let pass = passwordTextField.text, let name = (namec?.capitalized.isEmpty)! ? nil:namec?.capitalized {
            FIRAuth.auth()?.createUser(withEmail: email, password: pass, completion: { (user, error) in
                if user != nil {
                    //user found


                    let interval = NSDate().timeIntervalSince1970
                    let date = Date(timeIntervalSince1970: interval)
                    let dateFormatter = DateFormatter()
                  dateFormatter.dateFormat = "dd/MM/yyyy/HH/mm/SS"
                    // you can change the date format to whatever you wants
                    let dateString = dateFormatter.string(from: date)
                    print(dateString)
                    self.refD?.child("Users").child((user?.uid)!).setValue(["Email": email, "Name": name, "User Created": dateString])
                    print("User Created And Added To Database", email, name, dateString)
                    self.performSegue(withIdentifier: "registertologin", sender: self)
                }
            })
        }                 else {
            print(error!)
            let alert = UIAlertController(title: "Error Creating Account ", message: "\(error!.localizedDescription)", preferredStyle: UIAlertControllerStyle.alert)
            alert.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.default, handler: nil))
            self.present(alert, animated: true, completion: nil)
        }
    }
}

Answer 1

error 不在代码块内，在您的 else 语句中，error 变量不存在，代码应该看起来更像这样:

@IBAction func registerTapped(_ sender: Any) {
        print("tapped")
        let namec = nameTextField.text
        if let email = emailTextField.text, let pass = passwordTextField.text, let name = (namec?.capitalized.isEmpty)! ? nil:namec?.capitalized {
            FIRAuth.auth()?.createUser(withEmail: email, password: pass, completion: { (user, error) in
                if error != nil {
                    print(error!)
                    let alert = UIAlertController(title: "Error Creating Account ", message: "\(error!.localizedDescription)", preferredStyle: UIAlertControllerStyle.alert)
                    alert.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.default, handler: nil))
                    self.present(alert, animated: true, completion: nil)
                } else {
                    //Check if this is actually necessary, probbaly if user is nil that means your error variable is set to something, making this check unnecessary.
                    if user != nil {
                        //user found
                        let interval = NSDate().timeIntervalSince1970
                        let date = Date(timeIntervalSince1970: interval)
                        let dateFormatter = DateFormatter()
                      dateFormatter.dateFormat = "dd/MM/yyyy/HH/mm/SS"
                        // you can change the date format to whatever you wants
                        let dateString = dateFormatter.string(from: date)
                        print(dateString)
                        self.refD?.child("Users").child((user?.uid)!).setValue(["Email": email, "Name": name, "User Created": dateString])
                        print("User Created And Added To Database", email, name, dateString)
                        self.performSegue(withIdentifier: "registertologin", sender: self)
                    } else {
                        self.showAlertView(withTitle: "Error", andMessage: "User not found")
                    }
                }
            })
        } else {
            self.showAlertView(withTitle: "Missing input", andMessage: "Please make sure email and password fields are filled.")
        }
    }
}


func showAlertView(withTitle aTitle: String, andMessage aMessage: String) {
    let alertController = UIAlertController(title: aTitle message: aMessage, preferredStyle: .alert)
    let actionOk = UIAlertAction(title: "OK", style: .default, handler: nil)
    alertController.addAction(actionOk)

    //This part of code needs to run on the main thread since your alert might be
    //executed form the registration code block, which might be on a background thread
    DispatchQueue.main.async {
        self.presentViewController(alertController, animated: true, completion: nil)
    }
}