Registering Views for Multi-window Application

[symboli-rudolf]

Hello!
I am kind of stuck at this very basic step.
How do I correctly register a view that is used multiple times to open multiple windows?

The relevant code looks like this:

public partial class SubPage : ContentPage
{
	public SubPage()
	{
		InitializeComponent();
	}
}

public partial class MainPage : ContentPage
{
	readonly SubPage subPage;

	public MainPage(SubPage subPage)
	{
		InitializeComponent();
		this.subPage = subPage;
	}

	private void OnNewWindowClicked(object sender, EventArgs e)
	{
		Window newWindow = new()
		{
			Page = this.subPage,
	 	};
		Application.Current?.OpenWindow(newWindow);
	}
}

The views are registered in MauiProgram.cs like so:

public static class MauiProgram
{
	public static MauiApp CreateMauiApp()
	{
		var builder = MauiApp.CreateBuilder();
		builder
			.UseMauiApp<App>()
			.Services
				.AddSingleton<MainPage>()
				.AddTransient<SubPage>();
		return builder.Build();
	}
}

Currently, I can only open a window that uses a view once.
The second time I attempt to open another window using the same view, I get this error:
System.InvalidOperationException: 'MauiContext is null.'

I can "solve" the issue by not registering the view as a service, and instead creating a new instance of the view every time a window is opened. However, I am not sure if this is the right way to do things.

Window newWindow = new()
{
    Page = new SubPage(),
};
Application.Current?.OpenWindow(newWindow);

The code to reproduce my issue is here:
https://github.com/symboli-rudolf/maui-window-test-app
(This has only been tested on Windows.)

Any clues as to what I should be doing?

[symboli-rudolf]

Gotten some help from SO.

It seems I've been doing two things wrong:

1. A single view instance cannot be reused to show multiple window instances
2. IServiceProvider should be used to get the transient instance of the SubPage service

Fixing the two points above, MainPage now looks like this:

public partial class MainPage : ContentPage
{
	private readonly IServiceProvider services;

	public MainPage(IServiceProvider services)
	{
		InitializeComponent();
		this.services = services;
	}

	private void OnNewWindowClicked(object sender, EventArgs e)
	{
		Window newWindow = new()
		{
			Page = this.services.GetService<SubPage>(),
	 	};
		Application.Current?.OpenWindow(newWindow);
	}
}