ZipBrowser

I found this sample code at:

http://developer.apple.com/mac/library/samplecode/ZipBrowser/index.html

and as I was scanning through it, I noticed that the zip file was being read as raw data using offsets as defined by the zip file specification.

Searching through the Cocoa API, I didn't see any formal api for reading or writing zip files.

I was wondering if anyone was aware of a framework for reading and writing zip files or do I need to roll my own code to do this based on the specification found at

http://www.pkware.com/documents/casestudies/APPNOTE.TXT

(Yes, I know I could probably communicate with the shell and use the zip utility directly, but, for the moment, I am interested in a framework that has implemented the zip file specification.)

Thank you.