Xamarin.Forms Prism：特定于平台的服务的Android依赖项注入

Question

Im trying to inject a Android- and iOS-specific service, but on Android I get an error in App.xaml.cs about it not being able to resolve the parameter for LoginService

My App.xaml.cs :

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


        Container.RegisterInstance<ILoginService>(new LoginService(Container.Resolve<IClsDkwsService>()));
    }

My MainActivity.cs :

public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
    protected override void OnCreate(Bundle bundle)
    {
        TabLayoutResource = Resource.Layout.tabs;
        ToolbarResource = Resource.Layout.toolbar;

        base.OnCreate(bundle);

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

public class AndroidInitializer : IPlatformInitializer
{
    public void RegisterTypes(IUnityContainer container)
    {
        container.RegisterInstance<IClsCryptoService>(new Cls_crypto());
        container.RegisterInstance<IClsDkwsService>(new Cls_dkws());
    }
}

It looks like AndroidInitializer.RegisterTypes() is called after App.RegisterTypes() . I would like to avoid registering LoginService in each platform. How do I ensure all platform-specific services are registered in App.xaml.cs ?

Answer 1

Instead of trying to manually create instances of these dependencies, use the features of the DI container. You can register a type as a singleton in Unity by using

Container.RegisterType<IMyService, MyService>(new ContainerControlledLifetimeManager());