EmptyMauiApp/MauiApp/Views/BaseContentPage.cs

using MauiApp.ViewModels;

namespace MauiApp.Views;

public class BaseContentPage<T> : ContentPage where T : BasePageViewModel
{
    protected T ViewModel { get; }
    private bool _initialized = false;

    protected BaseContentPage()
    {
        ViewModel = MauiProgram.ServiceProvider.GetService<T>();
        BindingContext = ViewModel;

        ViewModel.View = this;
    }

    protected override async void OnAppearing()
    {
        base.OnAppearing();

        if (!_initialized)
        {
            _ = Task.Run(Initialize);
            _ = Task.Run(() => ViewModel.Initialize());
            _initialized = true;
        }

        _ = Task.Run(() => ViewModel.OnAppearing());
    }

    protected virtual Task Initialize()
    {
        return Task.CompletedTask;
    }

    protected override void OnDisappearing()
    {
        base.OnDisappearing();
        _ = Task.Run(() => ViewModel.OnDisappearing());
    }

    protected override void OnNavigatedTo(NavigatedToEventArgs args)
    {
        base.OnNavigatedTo(args);
        _ = Task.Run(() => ViewModel.OnNavigatedTo(args));
    }
}