xamarin.forms中的页面生命周期事件 [英] Page lifecycle events in xamarin.forms

问题描述

我刚刚开发了我的第一个xamarin.forms应用程序。我很高兴xamarin.forms，但我想念几个事件。

在xamarin.forms ContentPage中是否有任何页面生命周期事件？

我知道这两个：

  protected override void OnAppearing（）
 { 
} 
 
 protected override void OnDisappearing（）
 {
} 
  

但是OnAppearing（）事件只会触发一次。在Android上，当我按下开始按钮并返回到我的应用程序时，此事件不会再次触发。

是否有解决方法（如Windows Phone中的OnNavigatedTo）页）？

谢谢。

解决方案

所以当您的页面出现时，OnAppearing 事件触发。即您已经导航到该页面或从堆栈中的另一个页面返回到该页面。目前没有页面生命周期事件。页面％2F *> API文档

我想你正在谈论的是如果你把你的应用程序睡觉并导航回到code> OnAppearing 事件没有被触发，这是因为你的页面没有出现，因为它已经在那里，应用程序刚刚入睡。

您正在寻找的是 应用程序生命周期 ，其中包括以下方法：

  protected override void OnStart（） 
 {
 Debug.WriteLine（OnStart）; 
} 
 protected override void OnSleep（）
 {
 Debug.WriteLine（OnSleep）; 
} 
 protected override void OnResume（）
 {
 Debug.WriteLine（OnResume）; 
} 
  

然后可以使用 OnResume 事件来做你想要的。

Xamarin文档包括必须对旧的Xamarin项目进行这些事件的更改。例如您的共享库中的应用程序类必须从 Xamarin.Forms.Application 继承，并且还必须对 AppDelegate 和 MainActivity 。

I just developed my first xamarin.forms app. I am excited about xamarin.forms, but I miss several events.

Are there any page-lifecycle-events in a xamarin.forms ContentPage?

I know of these two:

protected override void OnAppearing()
{
}

protected override void OnDisappearing()
{
}

But the OnAppearing() event only fires once. On Android, when I push the start button and go back to my app, this event does not fire again.

Is there a workaround for this (like OnNavigatedTo in WindowsPhone-pages)?

Thanks.

解决方案

So the OnAppearing event is fired when your page is appearing. I.e. you have navigated to that page or back to that page from another in the Stack. There is currently no Page Lifecycle events as you can see from the API documentation

I think what you are talking about is if you put your application to sleep and navigate back into it the OnAppearing event is not fired, This is because your page hasn't appeared because it was already there, the application was just asleep.

What you are looking for is the App Lifecycle which includes methods such as:

protected override void OnStart()
{
    Debug.WriteLine ("OnStart");
}
protected override void OnSleep()
{
    Debug.WriteLine ("OnSleep");
}
protected override void OnResume()
{
    Debug.WriteLine ("OnResume");
}

You can then use the OnResume event to do what you are looking for.

That Xamarin Document includes the changes that must be made to old Xamarin projects to access these events. e.g. your App class in your shared library must inherit from Xamarin.Forms.Application and changes must also be made to the AppDelegate and MainActivity.

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