如何从列表视图中的项目单击打开另一个 xamarin 表单页面

Question

您好，我有一个在 Xamarin 表单中创建的列表视图，我想要它做的只是当用户单击列表视图中的一个选项时，它会将他们带到另一个 Xamarin 表单页面，在我的情况下它将是 ContactInfo

这是我的 xaml：

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="WebSearch.CountySelect" Title="ReadyMo">
  <StackLayout Padding="0,20,0,0">
   <Label Text="ReadyMo" FontAttributes="Bold" HorizontalOptions="Center" />
    <ListView x:Name="listView">
      <ListView.ItemTemplate>
        <DataTemplate>
          <ViewCell>
            <Grid>
              <Grid.ColumnDefinitions>
                <ColumnDefinition Width="0.5*" />
                <ColumnDefinition Width="0.2*" />
                <ColumnDefinition Width="0.3*" />
              </Grid.ColumnDefinitions>
              <Label Text="{Binding Name}" FontAttributes="Bold" HorizontalOptions="Center">
              </Label>
            </Grid>
          </ViewCell>
        </DataTemplate>
      </ListView.ItemTemplate>
    </ListView>
  </StackLayout>
</ContentPage>

这是我的代码：

using WebSearch;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using Xamarin.Forms;

namespace WebSearch
{
    public partial class CountySelect : ContentPage
    {

        public CountySelect()
        {
            InitializeComponent();


            var name = new List<County>
            {
                      new County("Adair"),
                      new County("Andrew"),
                      new County("Atchison"),
                      new County("Audrain"),
                      new County("Barry"),
                      new County("Barton"),
                      new County("Bates"),
                      new County("Benton"),
                      new County("Bollinger"),
                      new County("Boone"),
                      new County("Buchanan"),
                      new County("Butler"),
                      new County("Caldwell"),
                      new County("Callaway"),
                      new County("Camden"),
                      new County("Cape Girardeau"),
                      new County("Carroll"),
                      new County("Carter"),
                      new County("Cass"),
                      new County("Cedar"),
                      new County("Chariton"),
                      new County("Christian"),
                      new County("Clark"),
                      new County("Clay"),
                      new County("Clinton"),
                      new County("Cole"),
                      new County("Cooper"),
                      new County("Crawford"),
                      new County("Dade"),
                      new County("Dallas"),
                      new County("Daviess"),
                      new County("DeKalb"),
                      new County("Dent"),
                      new County("Douglas"),
                      new County("Dunklin"),
                      new County("Franklin"),
                      new County("Gasconade"),
                      new County("Gentry"),
                      new County("Greene"),
                      new County("Grundy"),
                      new County("Harrison"),
                      new County("Henry"),
                      new County("Hickory"),
                      new County("Holt"),
                      new County("Howard"),
                      new County("Howell"),
                      new County("Iron"),
                      new County("Jackson"),
                      new County("Jasper"),
                      new County("Jefferson"),
                      new County("Johnson"),
                      new County("Knox"),
                      new County("Laclede"),
                      new County("Lafayette"),
                      new County("Lawrence"),
                      new County("Lewis"),
                      new County("Lincoln"),
                      new County("Linn"),
                      new County("Livingston"),
                      new County("Macon"),
                      new County("Madison"),
                      new County("Maries"),
                      new County("Marion"),
                      new County("McDonald"),
                      new County("Mercer"),
                      new County("Miller"),
                      new County("Mississippi"),
                      new County("Moniteau"),
                      new County("Monroe"),
                      new County("Montgomery"),
                      new County("Morgan"),
                      new County("New Madrid"),
                      new County("Newton"),
                      new County("Nodaway"),
                      new County("Oregon"),
                      new County("Osage"),
                      new County("Ozark"),
                      new County("Pemiscot"),
                      new County("Perry"),
                      new County("Pettis"),
                      new County("Phelps"),
                      new County("Pike"),
                      new County("Platte"),
                      new County("Polk"),
                      new County("Pulaski"),
                      new County("Putnam"),
                      new County("Ralls"),
                      new County("Randolph"),
                      new County("Ray"),
                      new County("Reynolds"),
                      new County("Ripley"),
                      new County("Saline"),
                      new County("Schuyler"),
                      new County("Scotland"),
                      new County("Scott"),
                      new County("Shannon"),
                      new County("Shelby"),
                      new County("St. Charles"),
                      new County("St. Clair"),
                      new County("St. Francois"),
                      new County("St. Louis City"),
                      new County("St. Louis County"),
                      new County("Ste. Genevieve"),
                      new County("Stoddard"),
                      new County("Stone"),
                      new County("Sullivan"),
                      new County("Taney"),
                      new County("Texas"),
                      new County("Vernon"),
                      new County("Warren"),
                      new County("Washington"),
                      new County("Wayne"),
                      new County("Webster"),
                      new County("Worth"),
                      new County("Wright")
            };

            listView.ItemsSource = name;
            listView.ItemTapped += async (sender, args) =>
            {
                var item = args.Item as County;
                if (item == null) return;
                await Navigation.PushAsync(new ContactInfo(item));
                listView.SelectedItem = null;
            };

            Content = listView;


        }


    }
}

我对 Xamarin Forms 很陌生，所以任何帮助都会很棒:) 提前致谢！

Answer 1

所以我发现我的 app.cs 中的代码是： 公共类应用程序：

Application

    {
        public App()
        {
            MainPage = new MyFirstPage();
        }
    }

何时需要：

public class App : Application
{
    public App()
    {
        MainPage = new NavigationPage(new MyFirstPage());
    }
}

多一点研究大有帮助！ :)

Answer 2

应用程序类

public class App: Application
{
    public static NavigationPage MyNavigationPage;

    public App()
    {
        MyNavigationPage = new NavigationPage();
        MainPage = MyNavigation;
        MyNavigation.PushAsync(new Page_Countries, true);
    }
}

单击 BindableProperty 项的自定义 ListView

 public class MyListView : ListView
    {


        public MyListView()
        {
            this.ItemTapped += this.OnItemTapped;

        }

        public static BindableProperty ItemClickCommandProperty = BindableProperty.Create<MyListView, ICommand>(x => x.ItemClickCommand, null);

        public ICommand ItemClickCommand {
            get { return (ICommand)this.GetValue(ItemClickCommandProperty); }
            set { this.SetValue(ItemClickCommandProperty, value); }
        }


        private void OnItemTapped(object sender, ItemTappedEventArgs e) {
            if (e.Item != null && this.ItemClickCommand != null && this.ItemClickCommand.CanExecute(e)) {
                this.ItemClickCommand.Execute(e.Item);
                this.SelectedItem = null;
            }
        }

    }

XAML

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:customcontrols="clr-namespace:MyNameSpace.CustomControls;assembly=MyNameSpace"
             x:Class="MyNameSpace.Views.Page_Countries"
             Title="Countries">

<customcontrols:MyListView
                x:Name="listOfCountries"
                VerticalOptions="Fill"
                HorizontalOptions="Fill"
                ItemsSource="{Binding PropertyCountries}"
                SelectedItem="{Binding PropertySelectedItem}"
                ItemClickCommand="{Binding CountryItemClickCommand}" <---
 <ListView.ItemTemplate>
            <DataTemplate>
              <ViewCell>
                <ViewCell.View>
                  <StackLayout
                      Orientation="Horizontal"
                      HorizontalOptions="Fill"
                      VerticalOptions="Center"
                      Padding="5,0,5,0"
                      Spacing="10">
<Label

                          HorizontalOptions="FillAndExpand"
                       LineBreakMode="TailTruncation"
                          VerticalOptions="Center"
                          Text="{Binding CountryName}" />
</StackLayout>
                </ViewCell.View>
              </ViewCell>
            </DataTemplate>
          </ListView.ItemTemplate>
        </customcontrols:MyListView>

视图模型

class ViewModel_Countries
{
    private ObservableCollection<Models.Country> Countries;
    public ObservableCollection<Models.Country> PropertyCountries
    {
            set { SetProperty(ref Countries, value); }
            get { return Countries; }
    }

    private ICommand countryItemClickCommand;
    public ICommand CountryItemClickCommand;
    {
        get
        {
            return countryItemClickCommand ?? (countryItemClickCommand = new Command (async () => await ExecuteCountryClickCommand()));
        }
    }

private async Task ExecuteCountryClickCommand()
{
    App.MyNavigation.PushAsync(MyNewPage, true);
}

}