App.xaml.cs

using System;
using System.Windows;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace wpfGenericHost;

/// <summary>
///     Interaction logic for App.xaml
/// </summary>
public sealed partial class App
{
    private readonly IHost _host;

    public App()
    {
        _host = new HostBuilder()
            .ConfigureAppConfiguration((context, configurationBuilder) =>
            {
                configurationBuilder.SetBasePath(context.HostingEnvironment.ContentRootPath);
                configurationBuilder.AddJsonFile("appsettings.json", optional: false);
            })
            .ConfigureServices((context, services) =>
            {
                services.Configure<Settings>(context.Configuration);

                services.AddSingleton<ITextService, TextService>();
                services.AddSingleton<MainWindow>();
            })
            .ConfigureLogging(logging => { logging.AddConsole(); })
            .Build();
    }

    private async void Application_Startup(object sender, StartupEventArgs e)
    {
        await _host.StartAsync();

        var mainWindow = _host.Services.GetService<MainWindow>();
        mainWindow.Show();
    }

    private async void Application_Exit(object sender, ExitEventArgs e)
    {
        using (_host)
        {
            await _host.StopAsync(TimeSpan.FromSeconds(5));
        }
    }
}