The Core Foundation version of key-value pairs. Like many other basic CoreFoundation types, CFDictionary is toll-free bridged with Cocoa’s NSDictionary, which means you can safely cast an NSDictionary * to a CFDictionaryRef and vice versa.

CFDictionary retains it keys, in contrast to NSDictionary which copies its keys.

http://www.carbondev.com/site/?page=CFDictionary