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c#开发移动APP-Xamarin入门

日期：2018-10-21点击：416收藏

原文: c#开发移动APP-Xamarin入门

如果您在.net环境下做开发，并且对WPF技术有一定了解及应用，同时也想进入移动App开发领域，推荐使用Xamarin开发移动应用

关于Xamarin不做介绍，网上很多，这里主要涉及的是一些来自微软官网文章的翻译，希望能够帮助有需要的小伙伴，有疑问或文章有错误处，还请及时联系

最终效果

创建Phoneword 应用程序步骤如下：

在新窗口中点击 Cross-Platform，选中Mobile App (Xamarin.Forms) ，指定名称及路径

在 New Cross Platform App对话框中点击Blank App，在Code Sharing Strategy选中.NET Standard

打开MainPage.xaml可看到如下代码

用下述替换上述代码

<?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="Phoneword.MainPage"> <ContentPage.Padding> <OnPlatform x:TypeArguments="Thickness"> <On Platform="iOS" Value="20, 40, 20, 20" /> <On Platform="Android, UWP" Value="20" /> </OnPlatform> </ContentPage.Padding> <StackLayout> <Label Text="Enter a Phoneword:" /> <Entry x:Name="phoneNumberText" Text="1-855-XAMARIN" /> <Button x:Name="translateButon" Text="Translate" Clicked="OnTranslate" /> <Button x:Name="callButton" Text="Call" IsEnabled="false" Clicked="OnCall" /> </StackLayout> </ContentPage>

保存并关闭文件

在MainPage.xaml.cs文件中用如下代码替换模板代码

using System; using Xamarin.Forms; namespace Phoneword { public partial class MainPage : ContentPage { string translatedNumber; public MainPage () { InitializeComponent (); } void OnTranslate (object sender, EventArgs e) { translatedNumber = PhonewordTranslator.ToNumber (phoneNumberText.Text); if (!string.IsNullOrWhiteSpace (translatedNumber)) { callButton.IsEnabled = true; callButton.Text = "Call " + translatedNumber; } else { callButton.IsEnabled = false; callButton.Text = "Call"; } } async void OnCall (object sender, EventArgs e) { if (await this.DisplayAlert ( "Dial a Number", "Would you like to call " + translatedNumber + "?", "Yes", "No")) { var dialer = DependencyService.Get<IDialer> (); if (dialer != null) dialer.Dial (translatedNumber); } } } }

OnTranslate 和 OnCall方法会在对应按钮点击时执行
解决方案邮件添加-》新项

选择新建类PhoneTranslator
PhoneTranslator.cs代码如下

using System.Text; namespace Phoneword { public static class PhonewordTranslator { public static string ToNumber(string raw) { if (string.IsNullOrWhiteSpace(raw)) return null; raw = raw.ToUpperInvariant(); var newNumber = new StringBuilder(); foreach (var c in raw) { if (" -0123456789".Contains(c)) newNumber.Append(c); else { var result = TranslateToNumber(c); if (result != null) newNumber.Append(result); // Bad character? else return null; } } return newNumber.ToString(); } static bool Contains(this string keyString, char c) { return keyString.IndexOf(c) >= 0; } static readonly string[] digits = { "ABC", "DEF", "GHI", "JKL", "MNO", "PQRS", "TUV", "WXYZ" }; static int? TranslateToNumber(char c) { for (int i = 0; i < digits.Length; i++) { if (digits[i].Contains(c)) return 2 + i; } return null; } } }

新建接口IDialer
IDialer.cs中定义一个Dail方法，该方法必须在每一个平台上实现

namespace Phoneword { public interface IDialer { bool Dial(string number); } }

到这一步，常规代码已经完成，下面会实现指定平台拨号代码作为 DependencyService.

解决方案下右键Phoneword.iOS 项目选择添加新类PhoneDialer.cs,

using Foundation; using Phoneword.iOS; using UIKit; using Xamarin.Forms; [assembly: Dependency(typeof(PhoneDialer))] namespace Phoneword.iOS { public class PhoneDialer : IDialer { public bool Dial(string number) { return UIApplication.SharedApplication.OpenUrl ( new NSUrl ("tel:" + number)); } } }

在Phoneword.Android项目右键添加PhoneDialer.cs

using Android.Content; using Android.Telephony; using Phoneword.Droid; using System.Linq; using Xamarin.Forms; using Uri = Android.Net.Uri; [assembly: Dependency(typeof(PhoneDialer))] namespace Phoneword.Droid { public class PhoneDialer : IDialer { public bool Dial(string number) { var context = MainActivity.Instance; if (context == null) return false; var intent = new Intent (Intent.ActionDial); intent.SetData (Uri.Parse ("tel:" + number)); if (IsIntentAvailable (context, intent)) { context.StartActivity (intent); return true; } return false; } public static bool IsIntentAvailable(Context context, Intent intent) { var packageManager = context.PackageManager; var list = packageManager.QueryIntentServices (intent, 0) .Union (packageManager.QueryIntentActivities (intent, 0)); if (list.Any ()) return true; var manager = TelephonyManager.FromContext (context); return manager.PhoneType != PhoneType.None; } } }

在Phoneword.Android项目双击MainActivity.cs，并用一下代码替换

using Android.App; using Android.Content.PM; using Android.OS; namespace Phoneword.Droid { [Activity(Label = "Phoneword", Icon = "@mipmap/icon", Theme = "@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)] public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity { internal static MainActivity Instance { get; private set; } protected override void OnCreate(Bundle bundle) { TabLayoutResource = Resource.Layout.Tabbar; ToolbarResource = Resource.Layout.Toolbar; base.OnCreate(bundle); Instance = this; global::Xamarin.Forms.Forms.Init(this, bundle); LoadApplication(new App()); } } }

右键Phoneword.Android双击Properties，选中Android Manifest选项卡

在Required permissions部分使能CALL_PHONE权限

在Phoneword.UWP右键新建类PhoneDialer.cs,

using Phoneword.UWP; using System; using System.Threading.Tasks; using Windows.ApplicationModel.Calls; using Windows.UI.Popups; using Xamarin.Forms; [assembly: Dependency(typeof(PhoneDialer))] namespace Phoneword.UWP { public class PhoneDialer : IDialer { bool dialled = false; public bool Dial(string number) { DialNumber(number); return dialled; } async Task DialNumber(string number) { var phoneLine = await GetDefaultPhoneLineAsync(); if (phoneLine != null) { phoneLine.Dial(number, number); dialled = true; } else { var dialog = new MessageDialog("No line found to place the call"); await dialog.ShowAsync(); dialled = false; } } async Task<PhoneLine> GetDefaultPhoneLineAsync() { var phoneCallStore = await PhoneCallManager.RequestStoreAsync(); var lineId = await phoneCallStore.GetDefaultLineAsync(); return await PhoneLine.FromIdAsync(lineId); } } }