Creating the view model for the favorite photos

We will start by creating a ViewModel model that we will use for the view. In the ViewModel folder in the GalleryApp project, create a new class named MainViewModel:

public class MainViewModel : ViewModel
{
    private readonly IPhotoImporter photoImporter;
    private readonly ILocalStorage localStorage;

    public ObservableCollection<Photo> Recent { get; set; }    
    public ObservableCollection<Photo> Favorites { get; set; }

    public MainViewModel(IPhotoImporter photoImporter, ILocalStorage localStorage)
    {
         this.photoImporter = photoImporter;
         this.localStorage = localStorage;
    }

    public async Task Initialize()
    {
        var photos = await photoImporter.Get(0, 20, Quality.Low);

        Recent = photos;
        RaisePropertyChanged(nameof(Recent));

        await LoadFavorites();

        MessagingCenter.Subscribe<GalleryViewModel>(this, "FavoritesAdded", (sender) =>
        {
    ...