How to add IUserDialogs to Maui IOC Add Singleton for Acr.UserDialogs

I'm converting app to Maui. Old IOS through TinyIOC/FreshMvvm was

    FreshMvvm.FreshIOC.Container.Register<IUserDialogs>(UserDialogs.Instance);

so how should that look in MauiProgram.cs using built in IOC?

    builder.Services.AddSingleton<IRestService, RestService>();
    builder.Services.AddSingleton<ICacheManager, CacheManager>();
    builder.Services.AddSingleton<IUserDialogs,UserDialogs.Instance>();

Says Instance does not exist in the type UserDialogs.
and

   builder.Services.AddSingleton<IUserDialogs,UserDialogs>();

Says Static types cannot be used as type Arguments.

> How to add IUserDialogs to Maui IOC Add Singleton for Acr.UserDialogs

I tried to achieve it by following step:

MauiProgram.cs:

public static class MauiProgram
{
    public static MauiApp CreateMauiApp()
    {
        var builder = MauiApp.CreateBuilder();
        builder
            .UseMauiApp<App>()
            .ConfigureFonts(...)
            .ConfigureLifecycleEvents(events =>
            {
#if ANDROID
                events.AddAndroid(android => android.OnApplicationCreate(app => UserDialogs.Init(app)));
#endif
            });

#if ANDROID
        builder.Services.AddSingleton(UserDialogs.Instance);
#endif

       return builder.Build();
    }
}

App.xaml.cs:

public partial class App : Application
{
    public static IUserDialogs UserDialogs;
    public App(IUserDialogs userDialogs)
    {
        InitializeComponent();

        UserDialogs = userDialogs;

        MainPage = new AppShell();
    }
}

Page.xaml.cs to use it:

public partial class NewPage1 : ContentPage
{
    public NewPage1()
    {
        InitializeComponent();
        App.UserDialogs.Alert("sss");
        
       //UserDialogs.Instance.Alert("ss");
    }
}

However, this error occurs:

But I have added the code UserDialogs.Init(app), it still has the error above. I added breakpoints and found that It always executes this line of code first: builder.Services.AddSingleton(UserDialogs.Instance); instead of UserDialogs.Init(app).

Of course, if not add Singleton, use UserDialogs directly:

public partial class NewPage1 : ContentPage
{
    public NewPage1()
    {
        InitializeComponent();
        //App.UserDialogs.Alert("sss");

        UserDialogs.Instance.Alert("ss");
    }
}

It works well, and also will execute UserDialogs.Init(app).

I hope these can help you.

Update:

> How is your UserDialogs resolving in your ContentPage?

You need to initialize UserDialogs: way1(in MauiProgram.cs) or way2(in MainActivity.cs):

protected override void OnCreate(Bundle savedInstanceState)
{
    UserDialogs.Init(this);
    base.OnCreate(savedInstanceState);
}

Update2:

I found the way to solve it! The codes of App.xaml.cs and Page.xaml.cs above remain unchanged. And Change MauiProgram.cs:

public static class MauiProgram
{
    public static MauiApp CreateMauiApp()
    {
//initialize UserDialogs here 
#if ANDROID
            UserDialogs.Init(()=>Platform.CurrentActivity);
#endif

        var builder = MauiApp.CreateBuilder();
        builder
            .UseMauiApp<App>()
            .ConfigureFonts(fonts =>
            {
                fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
            });

#if ANDROID
            builder.Services.AddSingleton(UserDialogs.Instance);
#endif

        return builder.Build();
    }
}

It works well and can call builder.Services.AddSingleton(UserDialogs.Instance) normally.