How to remove the LoginViewController.swift and replace with a UITabBarController

LoginViewController.swift

class LoginViewController: UIViewController {

    // lots of code removed.
    
    @objc func buttonAction() {

        let windowScene = view.window?.windowScene
        let sceneDelegate = windowScene?.delegate as! SceneDelegate
      
        sceneDelegate.loadTabBarController().

    }
}

SceneDelegate.swift

import UIKit

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?

    
    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        
        guard let windowScene = (scene as? UIWindowScene) else { return }
        
        window = UIWindow(frame: windowScene.coordinateSpace.bounds)
        window?.windowScene = windowScene
        window?.rootViewController = LoginViewController()
        window?.makeKeyAndVisible()
        
    }
   
    func loadTabBarController() {
        
        let tabBarController = UITabBarController()
        
        let queueNC = UINavigationController(rootViewController: QueueViewController())
        let messagesVC = UINavigationController(rootViewController: MessagesViewController())
        
        tabBarController.viewControllers = [queueNC, messagesVC]
        
        window?.rootViewController = tabBarController
        window?.makeKeyAndVisible()
        
    }
}