如何在appdelegate xcode 11 swift 5中显示视图控制器

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        
        // 创建窗口对象
        window = UIWindow(frame: UIScreen.main.bounds)
        
        // 创建要显示的视图控制器对象
        let viewController = ViewController()
        
        // 设置窗口的根视图控制器
        window?.rootViewController = viewController
        
        // 显示窗口和根视图控制器
        window?.makeKeyAndVisible()
        
        return true
    }
}