struct UserModel {
  let firstName: String
  let lastName: String
  let email: String
}

 ├── Controller
 │   ├── HomeViewController.swift
 │   └── LoginViewController.swift
 ├── Model
 │   └── UserModel.swift
 ├── Service
 │   └── NetworkService.swift
 └── View
     ├── Home.swift
     └── LoginView.swift

import Foundation
 
struct User {
    let firstName: String
    let lastname: String
    let email: String
}

import UIKit
 
class LoginView: UIView {
 
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupView()
    }
 
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
 
    lazy var emailField: UITextField = {
        let field = UITextField();
        field.layer.borderWidth = 0.5
        field.layer.cornerRadius = 6
        field.placeholder = "Email"
        field.keyboardType = .emailAddress
        field.autocapitalizationType = .none
 
        let paddingView = UIView(frame: CGRect(x: 0, y: 0,
                width: 10, height: field.frame.size.height))
        field.leftView = paddingView
        field.leftViewMode = .always
 
        return field
    }()
 
    lazy var passwordField: UITextField = {
        let field = UITextField()
        field.layer.borderWidth = 0.5
        field.layer.cornerRadius = 6
        field.placeholder = "Password"
        field.keyboardType = .default
        field.isSecureTextEntry = true
        field.autocapitalizationType = .none
 
        let paddingView = UIView(frame: CGRect(x: 0, y: 0,
                width: 10, height: field.frame.size.height))
        field.leftView = paddingView
        field.leftViewMode = .always
 
        return field
    }()
 
    lazy var loginButton: UIButton = {
        let button = UIButton()
        button.setTitle("Login", for: .normal)
        button.titleLabel?.font = .systemFont(ofSize: 24, weight: .medium)
        button.setTitleColor(.white, for: .normal)
        button.backgroundColor = .systemIndigo
        button.alpha = 0.6
        button.layer.cornerRadius = 6
        button.isEnabled = false
 
        return button
    }()
 
 
 
    private func setupView() {
        backgroundColor = .systemBackground
        addSubview(loginButton)
        addSubview(emailField)
        addSubview(passwordField)
 
        loginButton.translatesAutoresizingMaskIntoConstraints = false
        emailField.translatesAutoresizingMaskIntoConstraints = false
        passwordField.translatesAutoresizingMaskIntoConstraints = false
 
        emailField.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
        emailField.widthAnchor.constraint(equalToConstant: 200).isActive = true
        emailField.heightAnchor.constraint(equalToConstant: 50).isActive = true
        emailField.bottomAnchor.constraint(equalTo: passwordField.topAnchor,constant: -15).isActive = true
 
        passwordField.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
        passwordField.centerYAnchor.constraint(equalTo: centerYAnchor).isActive = true
        passwordField.widthAnchor.constraint(equalToConstant: 200).isActive = true
        passwordField.heightAnchor.constraint(equalToConstant: 50).isActive = true
 
        loginButton.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
        loginButton.topAnchor.constraint(equalTo: passwordField.bottomAnchor, constant: 15).isActive = true
        loginButton.widthAnchor.constraint(equalToConstant: 100).isActive = true
        loginButton.heightAnchor.constraint(equalToConstant: 50).isActive = true
 
    }
}

 
import UIKit
 
class HomeView: UIView {
 
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupView()
    }
 
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
 
    lazy var welcomeLabel: UILabel = {
        let label = UILabel()
        label.text = "Welcome"
        label.font = .systemFont(ofSize: 32, weight: .medium)
 
        return label
    }()
 
    private func setupView() {
        backgroundColor = .systemBackground
        addSubview(welcomeLabel)
        welcomeLabel.translatesAutoresizingMaskIntoConstraints = false
 
        welcomeLabel.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
        welcomeLabel.centerYAnchor.constraint(equalTo: centerYAnchor).isActive = true
    }
}

import UIKit
 
class LoginViewController: UIViewController, UITextFieldDelegate {
    let loginView = LoginView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.addSubview(loginView)
        setupUI()
        loginView.emailField.delegate = self
        loginView.passwordField.delegate = self
        
        loginView.emailField.addTarget(self, action: #selector(validateField), for: .editingChanged)
        loginView.passwordField.addTarget(self, action: #selector(validateField), for: .editingChanged)
        
       
    }
    
    func setupUI() {
        loginView.translatesAutoresizingMaskIntoConstraints = false
        loginView.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
        loginView.heightAnchor.constraint(equalTo: view.heightAnchor).isActive = true
    }
    
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        if textField == loginView.emailField {
            loginView.passwordField.becomeFirstResponder()
        } else if textField == loginView.passwordField {
            performLogin()
        }
        
        return true
    }
    
    @objc func loginButtonTapped() {
        performLogin()
    }
    
    @objc private func validateField() {
        loginView.loginButton.isEnabled = loginView.emailField.text != "" && loginView.passwordField.text != ""
        
        if loginView.loginButton.isEnabled {
            loginView.loginButton.alpha = 1
            loginView.loginButton.addTarget(self, action: #selector(loginButtonTapped), for: .touchUpInside)
        } else {
            loginView.loginButton.alpha = 0.5
        }
    }
    
    func performLogin() {
        let email = loginView.emailField.text ?? ""
        let password = loginView.passwordField.text ?? ""
        print("logging...")
 
        
        let homeVC = HomeViewController()
        
        NetworkService.share.login(email: email, password: password) { success in
            if success {
                self.present(homeVC, animated: true)
                self.loginView.emailField.text = ""
                self.loginView.passwordField.text = ""
            } else {
                let alertController = UIAlertController(title: "เข้าไม่ได้อ่ะ", message: "แน่ใจนะว่า Email กับ Password ถูก ?", preferredStyle: .alert)
                let tryAction = UIAlertAction(title: "ลองใหม่", style: .default) { (action) in
                    print(action.title!)
                }
                alertController.addAction(tryAction)
                self.present(alertController, animated: true)
            }
        }
    }
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        self.view.endEditing(true)
    } 
}

import UIKit
 
class HomeViewController: UIViewController {
    let homeView = HomeView()
    var user: User!
 
    override func viewDidLoad() {
        super.viewDidLoad()
        user = NetworkService.share.getUser()
        greetingUser()
        view.addSubview(homeView)
        
        homeView.translatesAutoresizingMaskIntoConstraints = false
        homeView.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
        homeView.heightAnchor.constraint(equalTo: view.heightAnchor).isActive = true
    }
    
    private func greetingUser() {
        homeView.welcomeLabel.text = "👋 \(user.firstName) \(user.lastname)"
    }
}