If you have instantiated the NSArrayController in the xib/nib file, that is where you will see that (when you select the NSArrayController Object). If not, you will have to use a method to set it programatically.
Also, when you select the NSArrayController object in the xib, I believe that is where you select the class of the object that add: creates.
Also, when you select the NSArrayController object in the xib, I believe that is where you select the class of the object that add: creates.