public async Task ExecuteOnFavoriteCommandAsync(object sender)
        {
            PopularBrandsViewModel popularBrandsViewModel = (PopularBrandsViewModel)sender;

            popularBrandsViewModel.IsFavorite = !popularBrandsViewModel.IsFavorite;
            PopularBrandsFromServer[PopularBrandsFromServer.IndexOf(popularBrandsViewModel)].IsFavorite = popularBrandsViewModel.IsFavorite;
        }
        public async Task ExecuteOnDeleteCommandAsync(object sender)
        {
            PopularBrandsViewModel popularBrandsViewModel = (PopularBrandsViewModel)sender;

            PopularBrands.Remove(popularBrandsViewModel);
            PopularBrandsFromServer.Remove(popularBrandsViewModel);
        }
        public async Task ExecuteOnPerformSearchCommandAsync(object sender)
        {
            string textToSearch = string.Empty;

            try
            {
                textToSearch = (string)sender;
            }
            catch (Exception ex)
            {
                SearchBar searchBar = (SearchBar)sender;
                textToSearch = (searchBar.Text == null) ? "" : searchBar.Text;
            }

            PopularBrands = new ObservableCollection <PopularBrandsViewModel>(
                PopularBrandsFromServer.Where(x => x.ItemTitle.ToUpper().Contains(textToSearch.ToUpper()) ||
                                              x.Text.ToUpper().Contains(textToSearch.ToUpper())));
        }