Can't see the list of events/actions during the Ctrl+drag operation in Xcode

I working with NSxxx kind of controls. It is OS X project.

I expect to see the drop-down control "Event" between the fields "Name" and "Type", with the list of the control library events.

Why I can not see it?

Most NSControl subclassed objects are simple enough that you just respond to an @IBAction, and that is the "event." For more complex controls you can create outlets to a delegate and sometimes to a datasource as well (e.g. NSTableView).

Your question indicates you're using an NSSlider, and that is perhaps best dealt with using bindings in Xcode, not IBActions.