MeWeb/src/MeWeb.App/App.axaml.cs

using Avalonia;
using Avalonia.Controls;
using Avalonia.Controls.ApplicationLifetimes;
using Avalonia.Markup.Xaml;

using MeWeb.App.Services;
using MeWeb.App.ViewModels;
using MeWeb.App.Views;
using MeWeb.Core.Net;

using Microsoft.Extensions.DependencyInjection;

namespace MeWeb.App;

public partial class App : Application
{
  public static IServiceProvider Services { get; private set; }

  public static IPlatform Platform { get; set; } = new SystemPlatform();

  public override void Initialize()
  {
    AvaloniaXamlLoader.Load(this);
#if DEBUG
    this.AttachDeveloperTools();
#endif
  }

  public override void OnFrameworkInitializationCompleted()
  {
    Services = new ServiceCollection().AddMeWebApp(Platform).BuildServiceProvider();
    var stored = AppSettings.Read();
    Localizer.Instance.SetLanguage(Languages.Find(stored.Language) ?? Languages.ForCulture(System.Globalization.CultureInfo.CurrentUICulture));

    if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
      desktop.MainWindow = new MainWindow { Content = CreateMainView() };
    else if (ApplicationLifetime is IActivityApplicationLifetime activity)
      activity.MainViewFactory = CreateMainView;
    else if (ApplicationLifetime is ISingleViewApplicationLifetime single)
      single.MainView = CreateMainView();

    base.OnFrameworkInitializationCompleted();
  }

  static Control CreateMainView() => new MainView { DataContext = Services.GetRequiredService<MainViewModel>() };
}