listcollectionview groupingcolumns and calculating the amount and quantity

private void GetGroupedProducts(ObservableCollection<Product> products, ICollectionView view)
{
  view.GroupDescriptions.Add(new PropertyGroupDescription("Category.Name"));
  var group = view.Groups[0];
  MessageBox.Show(
    "The category is " + group.Name + " and there are " +
    group.ItemCount + " products in this category with a total value of " +
    group.Items.Cast<Product>().Sum(p => p.UnitPrice * p.UnitsInStock));
}