Implementing the INavigation interface using Shell

The implementation is very straightforward since each method is only calling Xamarin.Forms static methods provided by the Shell API.

Create the Navigator class, as shown in the following steps:

1. In the News project, add a new class called Navigator.
2. Add the following code to the class:

using System.Threading.Tasks;
using News.ViewModels;
using Xamarin.Forms;

namespace News
{
    public class Navigator : INavigate
    {
        public async Task NavigateTo(string route)
        {
            await Shell.Current.GoToAsync(route);
        }

        public async Task PushModal(Page page)
        {
            await Shell.Current.Navigation.PushModalAsync(page);
        }

        public async Task PopModal()
        {
            await Shell.Current.Navigation.PopModalAsync();
        }
    }
}

This is simply pass-through code that calls already existing methods.