Ios 无法在swift中显示UIAlertController

我有这个函数

func showMessageNew(msg:String,title: String){
        let alertController = UIAlertController(title: title, message: msg, preferredStyle: .alert)
        let okAction = UIAlertAction(title: "OK", style: .default)
        alertController.addAction(okAction)
        self.present(alertController, animated: true)
}

---

但是当我运行它时，我在控制台中有这样一个命令：

，它的视图不在窗口层次结构中
下面的代码可用于显示
UIAlertController

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
            self.showMessageNew(msg: "hi", title: "hi")
            }
        }

    func showMessageNew(msg:String,title: String){
        let alertController = UIAlertController(title: title, message: msg, preferredStyle: .alert)
        let okAction = UIAlertAction(title: "OK", style: .default)
        alertController.addAction(okAction)
        self.present(alertController, animated: true)
    }
}

为了显示警报，您需要一个父视图。您在哪里使用此函数？您的函数在VIEWDILOAD o VIEWEXPEND中？