如何使用 MVVM、Firebase 和委托在 Swift UIKit 中显示警报

Question

我想知道如何实现委托或function来帮助我在 ViewModel 中显示警报。 基本上我需要验证两个文本字段，当用户输入错误的密码或错误的 email 时，它应该触发警报。 触发此警报的 function 在ViewController内部，我需要创建一个新的 class (ViewModel)来帮助我验证文本字段并登录到 firebase

这是我的代码：

视图控制器

import UIKit
import FirebaseAuth

class ViewController: UIViewController, UIWindowSceneDelegate {
    
    //MARK: - @IBOutlets
    
    @IBOutlet weak var emailTextField: UITextField!
    @IBOutlet weak var passwordTextField: UITextField!
    @IBOutlet weak var startButton: UIButton!

   
    //MARK: - LifeCycle
    override func viewDidLoad() {
        super.viewDidLoad()
        setDelegates()
        startButton.isEnabled = false
    }


    //MARK: - Delegates

    func setDelegates()->Void {
        emailTextField.delegate = self
        passwordTextField.delegate = self
    }

    
    // Function that i need to trigger in the ViewModel

    fileprivate func showErrorMessage(_ errorMessage : String) {
        let alertController = UIAlertController(title: "UPS!", message: errorMessage, preferredStyle: .alert)
        alertController.addAction(UIAlertAction(title: "Aceptar", style: .default))
        
        self.present(alertController, animated: true, completion: nil)
    }


    // Function to go to the next ViewController

    fileprivate func navigateToHomeViewController() {
        let storyBoard : UIStoryboard = UIStoryboard(name: "Main", bundle:nil)
        let homeViewController = storyBoard.instantiateViewController(withIdentifier: "HomeViewController") as! HomeViewController
        homeViewController.modalPresentationStyle = .fullScreen
        self.present(homeViewController, animated: true, completion: nil)
    }

    // Function of the ViewModel all validations
    
    fileprivate func validateUserLogin(_ error: Error?, _ result: AuthDataResult?) {
        switch error {
        case .some(let error as NSError) where error.code == AuthErrorCode.wrongPassword.rawValue:
            // validate the text field and then show the alert, i need to this, but inside the ViewModel
            self.showErrorMessage("Contraseña incorrecta")
           
        case .some(let error as NSError) where error.code == AuthErrorCode.userNotFound.rawValue:
           // validate the text field and then show the alert, i need to this, but inside the ViewModel
            self.showErrorMessage("Correo incorrecto")
           
        case .some(let error):
           // validate the text field and then show the alert, i need to this, but inside the ViewModel
            self.showErrorMessage("Login error: \(error.localizedDescription)")
            self.hideActivityIndicatorView()
        case .none:
            if (result?.user) != nil {
                navigateToHomeViewController()
            }
        }
    }
    
    @IBAction func startButtonAction(_ sender: Any) {
        if let email = emailTextField.text, let password = passwordTextField.text{
    // Function to sing in firebase, it would be inside the ViewModel
            Auth.auth().signIn(withEmail: email, password: password){(result, error) in
                self.validateUserLogin(error, result)
            }
        }
    }
    

    fileprivate func validateFields() -> Bool {
            return (passwordTextField.text!.count >= 8) && (isValidEmail(emailTextField.text ?? ""))
        }
        

        fileprivate func updateView() {
            if(validateFields()){
                startButton.isEnabled = true
                startButton.tintColor = UIColor.blue
            }else{
                startButton.isEnabled = false
                startButton.tintColor = UIColor.gray
            }
        }

}


func isValidEmail(_ email: String) -> Bool {
    let emailRegEx = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,64}"

    let emailPred = NSPredicate(format:"SELF MATCHES %@", emailRegEx)
    return emailPred.evaluate(with: email)
}

//MARK: - Text Field Delegate Methods

extension ViewController : UITextFieldDelegate{
    
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString
            string: String) -> Bool {
            if textField == self.emailTextField {
                updateView()
            } else if textField == self.passwordTextField {
                updateView()
            }
            return true
        }
    
}

StoryBoard

Answer 1

这是解决方案，感谢 Not Bad。

Model

import Foundation

struct User{
    
    var email : String
    var password : String
}

视图模型

import Foundation
import FirebaseAuth

class AuthViewModel {
    var delegate: AuthViewModelDelegate?
    var user : User? = User(email: "", password: "")
    
    func checkCredentials(user: User) {
        Auth.auth().signIn(withEmail: user.email, password: user.password){(result, error) in
           switch error {
           case .some(let error as NSError) where error.code == AuthErrorCode.wrongPassword.rawValue:

                   self.delegate?.showError("Contraseña incorrecta")
                   self.delegate?.hideActivityIndicator()
           case .some(let error as NSError) where error.code == AuthErrorCode.userNotFound.rawValue:

                   self.delegate?.showError("Correo incorrecto")
                   self.delegate?.hideActivityIndicator()
                    
           case .some(let error):

                   self.delegate?.showError("Login error: \(error.localizedDescription)")
                   self.delegate?.hideActivityIndicator()

           case .none:
               if (result?.user) != nil {
                   let storyboard = UIStoryboard(name: "Main", bundle: nil)
                   let homeViewController = storyboard.instantiateViewController(identifier: "HomeViewController")
                   self.delegate?.navigateToHomeViewController(homeViewController)
                   self.delegate?.hideActivityIndicator()
               }
           }
       }
   }
}

看法

import UIKit
import FirebaseAuth

//MARK: - @ protocols

protocol AuthViewModelDelegate {
    func showError(_ message: String)
    func hideActivityIndicator()
    func navigateToHomeViewController(_ homeViewController: UIViewController)
}

class ViewController: UIViewController {
    
    //MARK: - @IBOutlets
    
    @IBOutlet weak var emailTextField: UITextField!
    @IBOutlet weak var passwordTextField: UITextField!
    @IBOutlet weak var startButton: UIButton!
    
    //MARK: - @ Variables
    
    var activityIndicator:UIActivityIndicatorView!
    var authViewModel : AuthViewModel = AuthViewModel()
   
    //MARK: - @ Life cycle
    
    override func viewDidLoad() {
        super.viewDidLoad()
        setDelegates()
        setupUI()
    }
    
    fileprivate func setupUI() {
        setActivityIndicator()
        startButton.isEnabled = false
    }
    
    func setDelegates()->Void {
        authViewModel.delegate = self
        emailTextField.delegate = self
        passwordTextField.delegate = self
    }
    
    func setActivityIndicator()->Void{
        activityIndicator = UIActivityIndicatorView(style: UIActivityIndicatorView.Style.medium)
        activityIndicator.center = view.center
        activityIndicator.isHidden = true
        self.view.addSubview(activityIndicator)
    }
    
    
    func displayActivityIndicatorView() -> () {
        self.view.isUserInteractionEnabled = false
        self.view.bringSubviewToFront(self.activityIndicator)
        self.activityIndicator.isHidden = false
        self.activityIndicator.startAnimating()
      }
    
    @IBAction func startButtonAction(_ sender: Any) {
        self.displayActivityIndicatorView()
        guard let email = emailTextField.text else {return}
        guard let password = passwordTextField.text else {return}
        
        self.authViewModel.user?.email = email
        self.authViewModel.user?.password = password
        
        self.authViewModel.checkCredentials(user: self.authViewModel.user!)
            
    }
    
    fileprivate func validateFields() -> Bool {
            return (passwordTextField.text!.count >= 8) && (isValidEmail(emailTextField.text ?? ""))
        }
        

        fileprivate func updateView() {
            if(validateFields()){
                startButton.isEnabled = true
            }else{
                startButton.isEnabled = false
            }
        }

}


func isValidEmail(_ email: String) -> Bool {
    let emailRegEx = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,64}"

    let emailPred = NSPredicate(format:"SELF MATCHES %@", emailRegEx)
    return emailPred.evaluate(with: email)
}

//MARK: - Text Field Delegate Methods

extension ViewController : UITextFieldDelegate{
    
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString
            string: String) -> Bool {
            if textField == self.emailTextField {
                updateView()
            } else if textField == self.passwordTextField {
                updateView()
            }
            return true
        }
    
}

//MARK: - @ AuthViewModel Delegate Methods

extension ViewController : AuthViewModelDelegate{
    func hideActivityIndicator() {
        DispatchQueue.main.async {
            if !self.activityIndicator.isHidden{
               DispatchQueue.main.async {
                   self.view.isUserInteractionEnabled = true
                   self.activityIndicator.stopAnimating()
                   self.activityIndicator.isHidden = true

               }
           }
        }
    }
    
    func navigateToHomeViewController(_ homeViewController: UIViewController) {
        (UIApplication.shared.connectedScenes.first?.delegate as? SceneDelegate)?.changeRootViewController(homeViewController)
    }
    
    func showError(_ message: String) {
        DispatchQueue.main.async {
            let alertController = UIAlertController(title: "UPS!", message: message, preferredStyle: .alert)
            alertController.addAction(UIAlertAction(title: "Aceptar", style: .default))
            
            self.present(alertController, animated: true, completion: nil)
        }
    }
}