如何从 Xamarin.Forms 中的 NavigationStack 中删除模态页面 [英] How to remove a modal page from NavigationStack in Xamarin.Forms

问题描述

这是我的Navigation 的示例:

Here's an example for my Navigation:

LoginPage ( Login_Click  ) -> MainPage   | Block BackButton
MainPage  ( Logout_Click ) -> LoginPage  | Block going back to the MainPage

目前我正在使用此代码在成功登录后显示MainPage.

Currently I am using this code to show the MainPage after a successful login.

 await Navigation.PushModalAsync(new MainPage());

我不希望用户通过点击PreviousButton(Android)返回登录页面.

I DON'T want the users to go back by hitting the PreviousButton(Android) to return to the LoginPage.

注销时相同的故事.

有没有办法在成功登录后从 NavigationStack 中删除 LoginPage(并在注销时删除 MainPage)?

Is there a way to remove the LoginPage from the NavigationStack after a successful login (and remove the MainPage when logged out) ?

注意:

这是模态的.我没有使用 NavigationPage.

This is modal. I am not using a NavigationPage.

推荐答案

您正在寻找 PopToRootAsync.因此，您的用户输入所需的信息并点击登录按钮，您执行登录验证，如果成功，您设置一个新的 MainPage，然后设置一个新的 MainPage 然后 PopToRootAsync 弹出除根页面之外的所有页面离开导航堆栈.

You are looking for PopToRootAsync. So your user enters required info and they tap a login button, you perform your login verification and if success you set a new MainPage and then PopToRootAsync which pops all but the root Page off the navigation stack.

更新:由于 PopToRootAsync 在各种平台上完成的方式，您需要从 NavigationPage 开始，但可以将其删除为登录过程后的根页面.

Update: Due to the way PopToRootAsync is done across the various platforms, you need to start from a NavigationPage but can remove it as your root page after your login process.

因此，在您的应用程序构造函数中，不要只创建您的 LoginPage，而是将其放入 NavigationPage 但隐藏导航栏不会影响您的 LoginPage 屏幕布局:

So in your Application constructor, instead of just creating your LoginPage, place it into a NavigationPage but hide the navigation bar so it does not effect your LoginPage screen layout:

public App()
{
    var navPage = new NavigationPage(new LoginPage());
    NavigationPage.SetHasNavigationBar(navPage.CurrentPage, false);
    MainPage = navPage;
}

然后在您的 LoginPage 中，您可以将 Application.Current.MainPage 设置为任何 Page 类(不> 必须是一个 NavigationPage) 然后 PopToRootAsync 才能到达它并从导航层次结构中完全删除您的 LoginPage.

Then within your LoginPage you can set the Application.Current.MainPage to any Page class (does not have to be a NavigationPage) and then PopToRootAsync to get to it and totally remove your LoginPage from the navigation hierarchy.

public partial class LoginPage : ContentPage
{
    public LoginPage()
    {
        InitializeComponent();
        loginDone.Clicked += OnLoginClick;
    }
    async void OnLoginClick(object sender, EventArgs e)
    {
        // If Login is complete/successful - set new root page
        if (YourLoginMethod()) {
            Application.Current.MainPage = new MainApplicationPage();
            // Pops all but the root Page off the navigation stack, with optional animation.
            await Navigation.PopToRootAsync(true);
        }
    }
}

注意:仅在 iOS 和 Android

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