Omninetworking:
here: not been ported to iPhone, small changes to the source code are necessary.
here: Omni itself does not use Omninetworking on Mac much, with several failing cases.
cocoahttpserver from code.google (Not apple’s), i.e. Deusty’s: bonjour broadcasting, extremely fast, memory efficient, multi-thread, etc.
Deusty also provides cocoaasyncsocket from code.google:
Distributed Objects (DO): using DO restricts on cocoa.
Apple’s URL loading system: NSURL
Cocoa stream programming: if you want to code your own protocol.
some discussions on stackoverflow
