如何从appdelegate中打开弹出窗口？

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        
        // 创建弹出窗口
        let alertController = UIAlertController(title: "提示", message: "这是一个弹出窗口示例", preferredStyle: .alert)
        
        // 添加按钮
        let okAction = UIAlertAction(title: "确定", style: .default) { (action) in
            // 处理确定按钮点击事件
        }
        alertController.addAction(okAction)
        
        // 显示弹出窗口
        window?.rootViewController?.present(alertController, animated: true, completion: nil)
        
        return true
    }
}