How to make constructor injection of INavigator works?

[LITTOMA]

In App.OnLaunched, I called IHostBuilder.UseNavigation(ReactiveViewModelMappings.ViewModelMappings, RegisterRoutes),
And

 .ConfigureServices((context, services) =>
 {
     // Register view models
     //services.AddTransient<MyViewModel>();
 })

The ViewModel is defined as below:

    public class MyViewModel
    {
        private readonly INavigator navigator;

        public MyViewModel(INavigator navigator)
        {
            this.navigator = navigator;
        }
    }

However, when I tried to resolve the ViewModel by Host.Services.GetRequiredService<T>(), I always got a null for the INavigator parameter in the constructor.

[LITTOMA]

OK, I figured it out.
I have to call builder.Window.InitializeNavigationAsync so that the navigator can be injected to the constructor correctly.
I also register the navigator instance to the service provider in initialNavigate so I can resolve it anywhere.

builder.Window.InitializeNavigationAsync(
    async () => builder.Build(),
    initialNavigate: async (svc, nav) =>
    {
        svc.AddSingletonInstance<INavigator>(nav);
        await nav.NavigateViewModelAsync<IntroViewModel>(this);
    }
);