public override UITableViewCell GetCell (UITableView tableView, NSIndexPath indexPath)
{
var item = AllItems [indexPath.Row];
var cell = tableView.DequeueReusableCell ("Item", indexPath);
cell.TintColor = UIColor.Black;
cell.TextLabel.Text = item;
cell.Accessory = SelectedItems.Contains(item) ? Checkmark : None;
return cell;
}