The Objective-C library uses generic Cocoa that works in both Mac and iPhone apps. The library is not meant for someone new to writing Cocoa applications, however; get some practice first with a good book and some simpler projects.
The sample applications that are included with the library are for Mac, but the library usage would be the same for an iPhone application. Only the user interface code would be different (AppKit and UIKit are similar but not identical), and there is very little user interface code in the examples.