Can some explain the retain cycles problem with a sample program?
I've got just the right article(s) for you:
http://cocoawithlove.com/2010/06/assign-retain-copy-pitfalls-in-obj-c.html
http://cocoawithlove.com/2009/07/rules-to-avoid-retain-cycles.html
http://developer.apple.com/iphone/library/documentation/Cocoa/Conceptual/MemoryMgmt/MemoryMgmt.html
http://www.markj.net/iphone-memory-management-tutorial-video/