typedef struct __CFKeyedArchiverUID* CFKeyedArchiverUIDRef;
CFTypeID _CFKeyedArchiverUIDGetTypeID (void);
CFKeyedArchiverUIDRef _CFKeyedArchiverUIDCreate (CFAllocatorRef allocator, uint32_t value);
uint32_t _CFKeyedArchiverUIDGetValue (CFKeyedArchiverUIDRef uid);
CFKeyedArchiverUID is the "8th property list object" for supporting NSKeyedArchiver. It is essentially a 32-bit integer, but this specific type is used to denote a link in the object graph.
This type will appear as <NSCFType 0xXXXXXXXX> when NSLog-ing it, which is not useful. Apple's Property List Editor does not recognize this type, so if you edit a plist generated by NSKeyedArchiver, data will be lost.
References
- Source code of this type: http://opensource.apple.com/source/CF/CF-299.33/Parsing.subproj/CFBinaryPList.c