What needs to be added to AppDelegate.swift to be able to not use a storyboard

NoStoryboardAppDelegate.swift

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        window = UIWindow(frame: UIScreen.main.bounds)
        window?.rootViewController = YourFirstViewController()
        window?.makeKeyAndVisible()
        return true
    }
    
    // The rest of AppDelage.swift
}