How to retrieve the current selection of an NSPopUpButtonCell?

Question

I am using an NSPopUpButtonCell in an NSTableView. The popup button has a binding to an NSArray property offered by the ApplicationDelegate. When I select a menu item of the popup button I expect to retrieve the current selection or its index. I added an IBAction to being informed and also set up an NSMenuDelegate. Both return index = 0 at all times.

// indexOfSelectedItem is always 0.
NSInteger indexOfSelectedItem = [m_popUpButtonCell indexOfSelectedItem];

I created an example project with the aforementioned configuration. Hopefully you can clarify things.

Answer 1

The article Implementing To-One Relationships Using Pop-Up Menus answered my question.
I updated the example project.