Hmmm...I hadn't thought of doing that. All of the examples I've seen don't ever touch the appDelegate code (other than to add the main view to the window), so I wasn't sure if that was politically correct.
A little more detail on where the data comes from...I read the default (or user-saved) .plist when the first view controller loads. The first view controller acts as a navigation controller and is able to shuffle the arrays around to the other views without a problem.
Now, if I put the saveData method in the app delegate as you described, it would make things a lot easier; however, I'm thinking I will have to pass the array(s) to the saveData method (obviously). I read something in the Objective-C docs on Apple's website that talked about calling a method like this:
[receiver makeGroup:group, memberOne, memberTwo, memberThree];
I'm thinking I can pass my arrays to a method like this, but how do you define this particular method (note the commas between the "group" and "memberXXXX" parameters)?. Apple docs tend to have a few holes in them -- specifically telling you how to define something that's used in one of their examples -- which is why I bought your book in the first place...