Not sure what you are trying to do, but you can only add one item to the list and that becomes the selected item. So ListBoxName.rawValue will give you the value they selected. If they did not select anything then the value will be null....which means they did not add an entry either.
Okay, it's working. Only if the user selects something in the listbox. For that matter - how can I select automatically always the first item in the listbox once something is dynamically added to the listbox?