导航-PopAsync（）似乎不起作用

Question

我正在使用Xamarin创建一个接受电子邮件，密码字段的登录表单。

用户输入详细信息并单击登录按钮后，将不会显示任何警告框。 它来自应用程序。 这是代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlTypes;

using Xamarin.Forms;
using SQLite;
using System.IO;

namespace LoginPage.Views
{
 public class AddDetails : ContentPage
 {
    private Entry _emailEntry;
    private Entry _passwordEntry;
    private Button _saveButton;

    string _dbPath = Path.Combine(System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal), "myDB.db3");
    public AddDetails()
    {
        this.Title = "Add Details";
        StackLayout stackLayout = new StackLayout();



        _emailEntry = new Entry();
        _emailEntry.Keyboard = Keyboard.Text;
        _emailEntry.Placeholder = "Email";
        stackLayout.Children.Add(_emailEntry);


        _passwordEntry = new Entry();
        _passwordEntry.Keyboard = Keyboard.Text;
        _passwordEntry.Placeholder = "Password";
        stackLayout.Children.Add(_passwordEntry);

        _saveButton = new Button();
        _saveButton.Text = "Login User";
        _saveButton.Clicked += _saveButton_Clicked;
        stackLayout.Children.Add(_saveButton);

        Content = stackLayout;
    }

    private async void _saveButton_Clicked(object Sender, EventArgs e)
    {
        var db = new SQLiteConnection(_dbPath);
        db.CreateTable<User>();

        var maxPk = db.Table<User>().OrderByDescending(c => c.Id).FirstOrDefault();

        User user = new User()
        {
            Id = (maxPk == null ? 1 : Convert.ToInt32(maxPk.Id) +1),
            Email = _emailEntry.Text,
            Password = _passwordEntry.Text

        };

        db.Insert(user);
        await DisplayAlert(null, user.Email + "Saved", "Ok");
        await Navigation.PopAsync();
     }

     }
     }

显示登录屏幕，但没有警告框显示“电子邮件已保存”。 而且，它突然从应用程序中消失

Answer 1

您是否设置MainPage = new NavigationPage（new Page1Xaml（））;

请点击以下链接https://docs.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/navigation/