在现有 Xamarin.Forms 共享应用程序中实施 Prism

Question

我想知道在现有的 Xamarin.Forms 共享项目中是否有一种有效的方法来实施 Prism。我相信其他人也想知道他们是否可以从 Prism 提供的产品中获利，而不必将他们现有的项目转换为 PCL 项目。我发现的所有现有示例都显示了一个 PCL 项目（可能有充分的理由）。

为了尝试在我的项目中实施 Prism，我为每个平台项目安装了 Prims.Unity.Forms nuget。我试图从 PrismApplication 继承：

public partial class App : PrismApplication 
{ }

但是，这是行不通的。应用程序 class 不允许我从不同的基础继承 class。

将以下行添加到我的 android 项目没有帮助：

protected override void OnCreate(Bundle bundle)
{      
   LoadApplication(new App(new AndroidInitializer()));
}

public class AndroidInitializer : IPlatformInitializer
{
   public void RegisterTypes(IUnityContainer container)
   { }
}

也许我遗漏了一些东西或尝试了一些结构上不可能的东西。

Answer 1

是的，完全有可能。

首先，确保安装了 nuget 包。

例如，对于 Prism 和 Unity，您需要：

<package id="Prism.Core" version="6.3.0" ... />
<package id="Prism.Forms" version="6.3.0" .../>
<package id="Prism.Unity.Forms" version="6.3.0" ... />
<package id="Unity" version="4.0.1" ... />

添加丢失的文件夹（仅用于订购）

And move your existing page to the Views folder, but remember to adjust the namespaces or your binding just won't work.

更改应用程序基类型

记得在代码中更改应用程序基类型 XAML。

using Prism.Unity;
using Xamarin.Forms;

namespace XamPrismShared
{
    public partial class App : PrismApplication
    {
        public App (IPlatformInitializer platformInitializer):base(platformInitializer)
        {                       
        }

    }
}

设置第一页及其 ViewModel

实施 OnInitialized 和 RegisterTypes。请记住，您需要将要与 Prism 一起使用的每种类型注册为一个页面。

using Prism.Unity;
using Xamarin.Forms;

namespace XamPrismShared
{
    public partial class App : PrismApplication
    {
        public App (IPlatformInitializer platformInitializer):base(platformInitializer)
        {                       
        }

        protected override void OnInitialized()
        {
            InitializeComponent();
            NavigationService.NavigateAsync("MainPage");
        }

        protected override void RegisterTypes()
        {
            Container.RegisterTypeForNavigation<NavigationPage>();
            Container.RegisterTypeForNavigation<MainPage>();            
        }                
    }
}

如果您已有页面

将 ViewModelLocator.AutowireViewModel="True" 添加到您现有的视图中，以允许 Prism 自动绑定 与其各自的 ViewModel.

<?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:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
             prism:ViewModelLocator.AutowireViewModel="True" x:Class="x:Class="XamPrismShared.Views.MainPage"" Title="MainPage">
   <Label Text="{Binding Title}" 
           VerticalOptions="Center" 
           HorizontalOptions="Center" />
</ContentPage>

添加缺少的 ViewModel

using Prism.Mvvm;

namespace XamPrismShared.ViewModels
{
    public class MainPageViewModel : BindableBase
    {
        public MainPageViewModel()
        {
            Title = "Hi from Prism.";
        }

        public string Title { get; set; }
    }
}

在每个平台项目中添加平台初始值设定项

添加缺少的平台初始化程序并修复 Xamarin.Forms 加载。

对于Android,

using Android.App;
using Android.Content.PM;
using Android.OS;
using Microsoft.Practices.Unity;
using Prism.Unity;

namespace XamPrismShared.Droid
{
    [Activity (Label = "XamPrismShared", Icon = "@drawable/icon", Theme="@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
    public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {
        protected override void OnCreate (Bundle bundle)
        {
            TabLayoutResource = Resource.Layout.Tabbar;
            ToolbarResource = Resource.Layout.Toolbar; 

            base.OnCreate (bundle);

            global::Xamarin.Forms.Forms.Init (this, bundle);
            LoadApplication (new XamPrismShared.App(new AndroidPlatformInitializer()));
        }
    }

    public class AndroidPlatformInitializer : IPlatformInitializer
    {
        public void RegisterTypes(IUnityContainer container)
        {

        }
    }
}

对于iOS,

using Foundation;
using Microsoft.Practices.Unity;
using Prism.Unity;
using UIKit;

namespace XamPrismShared.iOS
{   
    [Register("AppDelegate")]
    public partial class AppDelegate : global::Xamarin.Forms.Platform.iOS.FormsApplicationDelegate
    {
        public override bool FinishedLaunching(UIApplication app, NSDictionary options)
        {
            global::Xamarin.Forms.Forms.Init ();
            LoadApplication (new XamPrismShared.App(new iOSPlatformInitializer()));

            return base.FinishedLaunching (app, options);
        }
    }

    public class iOSPlatformInitializer : IPlatformInitializer
    {
        public void RegisterTypes(IUnityContainer container)
        {

        }
    }
}

瞧瞧

If you have any question or want to check, you can review the code in Github https://github.com/jesulink2514/Xamarin-Prism-shared-project

在现有 Xamarin.Forms 共享应用程序中实施 Prism

Implement Prism in existing Xamarin.Forms Shared Application

c#

prism

xamarin

xamarin.forms