Four headers worth reading
- <Foundation/FoundationErrors.h>
- <AppKit/AppKitErrors.h>
- <CoreData/CoreDataErrors.h>
- <WebKit/WebKitErrors.h>
These four headers define error codes in NSCocoaErrorDomain, which you can use in and expect from NSError instances.
There’s also <QuickTime/QuickTimeErrors.h>, but its error codes are OSStatuses (usable with NSOSStatusErrorDomain), which makes them better-known to begin with.