ChatRoomVC.swift

var username: String = "Anonymous"
  var webSocketTask: URLSessionWebSocketTask!
  var chatHistory: [String] = []
  
  var safeArea: UILayoutGuide!
  
  let tableView = UITableView()
  let messageTextField = UITextField()
  let sendButton = UIButton()

  override func viewDidLoad() {
    super.viewDidLoad()
    view.backgroundColor = .black
    safeArea = view.layoutMarginsGuide
    navigationItem.title = "Chat Room"
    navigationItem.rightBarButtonItem = UIBarButtonItem(title: username, style: .plain, target: nil, action: nil)
    
    setupTableView()
    setupMessageTextField()
    setupSendButton()
    
    setupWebSocket()
    receiveMessage()
  }
  
  func setupTableView() {
    view.addSubview(tableView)
    tableView.translatesAutoresizingMaskIntoConstraints = false
    
    let top = tableView.topAnchor.constraint(equalTo: safeArea.topAnchor)
    let width = tableView.widthAnchor.constraint(equalTo: view.widthAnchor)
    let height = tableView.heightAnchor.constraint(equalTo: safeArea.heightAnchor, multiplier: 0.33)
    NSLayoutConstraint.activate([top, width, height])
    
    tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cellid")
    tableView.dataSource = self
  }
  
  func setupMessageTextField() {
    view.addSubview(messageTextField)
    messageTextField.translatesAutoresizingMaskIntoConstraints = false
    
    let top = messageTextField.topAnchor.constraint(equalTo: tableView.bottomAnchor, constant: 5)
    let width = messageTextField.widthAnchor.constraint(equalTo: view.widthAnchor)
    let height = messageTextField.heightAnchor.constraint(equalToConstant: 35)
    NSLayoutConstraint.activate([top, width, height])
    
    messageTextField.backgroundColor = .white
    messageTextField.placeholder = "Enter message here.."
    messageTextField.clearButtonMode = .whileEditing
  }
  
  func setupSendButton() {
    view.addSubview(sendButton)
    
    sendButton.translatesAutoresizingMaskIntoConstraints = false
    let centerY = sendButton.centerYAnchor.constraint(equalTo: view.centerYAnchor)
    let centerX = sendButton.centerXAnchor.constraint(equalTo: view.centerXAnchor)
    let width = sendButton.widthAnchor.constraint(equalToConstant: 200)
    NSLayoutConstraint.activate([centerY, centerX, width])
    
    sendButton.setTitle("Send Message", for: .normal)
    sendButton.setTitleColor(.black, for: .normal)
    sendButton.setTitleColor(.blue, for: .highlighted)
    sendButton.backgroundColor = .white
    sendButton.layer.cornerRadius = 4
    
    sendButton.addTarget(self, action: #selector(sendMessage), for: .touchUpInside)
  }