Implementing realtime apps on the iPhone?

Things like presence notification needed for IM that messenger apps have. Kik does this especially well and managed to improve the texting experience many-fold.

If this were a web application, we would probably do a comet imple开发者_运维百科mentation and run an event loop server to handle the connections and keep either a flash/web socket or long polling connection open on the client (Socket.IO ftw).

I'm not too sure about iPhone, with the connections over 3g+wifi and all: - maybe NSURLRequest handles all that stuff for you and it's as simple as keeping a long running long polling connection on a background thread and register notifications onto it?

Anyways, would appreciate some pointers from anybody who's implemented something realtime on the iPhone.

Well I'll just respond now for other peoples' reference:

You can use Node.js with Socket.io basically, and implement long polling on the iPhone. There's a library somewhere IIRC, but it's relatively simple just to implement yourself:

• Implement a state machine of sorts on the phone to switch between open request and getting back data, fire off another request.
• Implement a heartbeat (you don't want to hit the HTTP timeout anyways) of like 5 seconds, read the socket.io github page for more info on the protocol so you can interface with Node.