Xamarin.form Page Navigation in mvvm

Question

I am working on xamarin.form cross-platform application , i want to navigate from one page to another on button click. As i cannot do Navigation.PushAsync(new Page2());

Answer 1

Passing INavigation through VM constructor is a good solution indeed, but it can also be quite code-expensive if you have deep nested VMs architecture.

Wrapping INavigation with a singleton, accesible from any view model, is an alternative:

NavigationDispatcher Singleton:

 public class NavigationDispatcher
    {
        private static NavigationDispatcher _instance;

        private INavigation _navigation;

        public static NavigationDispatcher Instance =>
                      _instance ?? (_instance = new NavigationDispatcher());

        public INavigation Navigation => 
                     _navigation ?? throw new Exception("NavigationDispatcher is not initialized");

        public void Initialize(INavigation navigation)
        {
            _navigation = navigation;
        }
    }

Initializing in App.xaml.cs:

       public App()
       {
          InitializeComponent();
          MainPage = new NavigationPage(new MainPage());
          NavigationDispatcher.Instance.Initialize(MainPage.Navigation);
       }

Using in any ViewModel:

 ...
 private async void OnSomeCommand(object obj)
        {
            var page = new OtherPage();
            await NavigationDispatcher.Instance.Navigation.PushAsync(page);
        }
 ...