c# - Back navigation loads the page as its first state

Question

I pass a value to a page

NavigationService.Navigate("/SportsPage.xaml?Number=5",UriKind.Relative);

the Number value changes while user is in the page, it gets 10 for example. then he goes to another page, but after a back navigation from that page to this page, the number is still 5. like it is the first time. but I want it to be the number when the user left the page (i.e 10).

I can save it to the storage and retrieve it on navigationTo, but it is not the case.

Is it possible to return back to the page in its last state?

Answer 1

当您按下后退按钮时，页面将返回到其最后一个状态。问题是 OnNavigatedTo 事件在返回页面时会再次执行，因此您必须注意不要覆盖变量的值。

基本上，您的代码类似于：

protected virtual void OnNavigatedTo(NavigationEventArgs e)
{
    this.Number = this.NavigationContext.QueryString["Number"];
}

您应该将其更改为：

protected virtual void OnNavigatedTo(NavigationEventArgs e)
{
    if (e.NavigationMode != System.Windows.Navigation.NavigationMode.Back)
    {
         this.Number = this.NavigationContext.QueryString["Number"];
    }
}

这样，您在返回页面时不会覆盖变量的最后一个值。

Answer 2

您可以像这样在 App.xaml.cs 中创建一个全局变量：

public int Number { get; set; }.

并使用它进行操作：

(App.Current as App).Number = 5;