UIAlert错误，其视图不在窗口层次结构中 [英] UIAlert error, whose view is not in the window hierarchy

问题描述

我正在建立网络连接，

我将检查可达性代码放在viewDidLoad中，以便在没有网络的情况下通过提醒用户来通知用户。

I put checking reachability code in viewDidLoad, so that I notify User by alerting if there is not network.

这是我的代码，

class ViewController: UIViewController {
var reachability : Reachability?

override func viewDidLoad() {
    super.viewDidLoad()
    if reachability?.isReachable() == true
     {
         print("reachable")
     }else{

        let myAlert = UIAlertController(title: "No network", message:
            "Your network is not working", preferredStyle:
            UIAlertControllerStyle.Alert)
        let okAction = UIAlertAction(title: "Ok", style:
            UIAlertActionStyle.Default, handler: nil)
        myAlert.addAction(okAction)
        self.presentViewController(myAlert, animated: true, completion:
            nil)

    }

但是如果我尝试使用模拟器或手机，
会显示错误消息

but If I try on my simulator or cellphone, it shows error message that

2015-11-08 16： 43：52.173 PracticeReachability [5494：2661290]警告：尝试呈现其视图不在窗口层次结构中的视图！

2015-11-08 16:43:52.173 PracticeReachability[5494:2661290] Warning: Attempt to present on whose view is not in the window hierarchy!

我尝试放置

var myAlert = UIAlertController()

和
var myAlert：UIAlertController！

and var myAlert :UIAlertController!

两者都不起作用。

问题 >

我的其他Alerts在同一ViewController中可以正常工作。
为什么只有这种方法不起作用？

My other Alerts work fine in same ViewController. Why only this is not working?

又如何使它起作用？

推荐答案

我认为viewDidLoad中尚未将视图控制器的视图添加到屏幕中。尝试将代码移至viewDidAppear。

I don't think the view controller's view has been added to the screen yet in viewDidLoad. Try moving your code to viewDidAppear.

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