c#开发移动APP-Xamarin入门扩展

　　这节主要演示了如何通过添加第二个屏幕来跟踪应用程序的call历史来扩展Phoneword应用程序。最终如下:

 

 

　　按如下步骤扩展Phoneword

　　在Phoneword项目右键新建Content Page,命名为CallHistoryPage

 　　修改后CallHistoryPage.xaml如下：

xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
                   xmlns:local="clr-namespace:Phoneword;assembly=Phoneword"
                   xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                   x:Class="Phoneword.CallHistoryPage"
                   Title="Call History">
    <ContentPage.Padding>
        <OnPlatform x:TypeArguments="Thickness">
            <On Platform="iOS" Value="20, 40, 20, 20" />
            <On Platform="Android, UWP" Value="20" />
        OnPlatform>
    ContentPage.Padding>
    <StackLayout>
      <ListView ItemsSource="{x:Static local:App.PhoneNumbers}" />
    StackLayout>
ContentPage>

　　双击Phoneword项目的App.xaml.cs文件

 

 

　　添加PhoneNumbers属性的声明，在App构造函数中初始化该属性，并将MainPage属性初始化为NavigationPage。PhoneNumbers被用于存储应用程序打的每个电话号码

 

using System.Collections.Generic;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

[assembly: XamlCompilation(XamlCompilationOptions.Compile)]
namespace Phoneword
{
    public partial class App : Application
    {
        public static IList<string> PhoneNumbers { get; set; }

        public App()
        {
            InitializeComponent();
            PhoneNumbers = new List<string>();
            MainPage = new NavigationPage(new MainPage());
        }
        ...
    }
}

 

　　双击Phoneword项目的MainPage.xaml文件

　　在StackLayout控件的末尾添加一个按钮控件，该按钮被用于导航到拨打历史页面

<StackLayout VerticalOptions="FillAndExpand"
             HorizontalOptions="FillAndExpand"
             Orientation="Vertical"
             Spacing="15">
  ...
<Button x:Name="callButton" Text="Call" IsEnabled="false" Clicked="OnCall" />
  <Button x:Name="callHistoryButton" Text="Call History" IsEnabled="false"
          Clicked="OnCallHistory" />
StackLayout>

　　打开隐藏文件MainPage.xaml.cs，添加OnCallHistory事件处理程序方法，并修改OnCall事件处理程序方法，将转换后的电话号码添加到App.PhoneNumbers集合中，并且如果dialer变量不为null时使能callHistoryButton

using System;
using Xamarin.Forms;

namespace Phoneword
{
    public partial class MainPage : ContentPage
    {
        ...

        async void OnCall(object sender, EventArgs e)
        {
            ...
            if (dialer != null) {
                App.PhoneNumbers.Add (translatedNumber);
                callHistoryButton.IsEnabled = true;
                dialer.Dial (translatedNumber);
            }
            ...
        }

        async void OnCallHistory(object sender, EventArgs e)
        {
            await Navigation.PushAsync (new CallHistoryPage ());
        }
    }
}

　　下节剖析该扩展

 

转载于:https://www.cnblogs.com/0306Leaves/p/9823509.html