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

问题描述

以下是我的 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

当前，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)返回登录页面来返回.

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

登出时的故事相同.

是否存在一种方法，可以在成功登录后从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，您的用户输入了必填信息，然后他们点击了登录按钮，就执行了登录验证，如果设置成功，则先设置一个新的MainPage，然后再设置PopToRootAsync，它将除根页面之外的所有页面都弹出导航堆栈.

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:由于跨各种平台完成PopToRootAsync的方式，您需要从NavigationPage开始，但可以在登录过程后将其作为根页面删除.

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Application构造函数中，将其放置到NavigationPage中，而不是仅创建LoginPage，但隐藏导航栏，这样就不会影响LoginPage的屏幕布局:

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，可以将Application.Current.MainPage设置为任何Page类(不是是否必须是NavigationPage)，然后再按PopToRootAsync即可到达该类.从导航层次结构中完全删除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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