Objective-C / Cocoa / XCode新手：如何接收通知？

I couldn't get an example from a cocoa programming book to work (part of the problem I think is XCode is out of date). It didn't mention anything special I had to do to receive notifications from NSTableView other than make the appropriate connections in IB. The app is a program with a NSTextField for User input and when a button is clicked an instance of NSSpeechSynthesizer will speak the line entered. Im supposed to be able to switch speaking voices by selecting a row on the table view. I can click on, the app technically works but I can't change the default speaking voice by clicking a row on NSTableView on the GUI:I couldn't get an example from a cocoa programm