Socket connection on iPhone (IOS 4.x)

I am working on a Chatting application (needs to connect to a server) on iPhone. The sending packet from iPhone shouldn't be a problem.

But I would like to know whether it is possible for iPhone to establish a incoming socket开发者_开发百科 connection to server continuously or forever under mobile environment.

OR What do I need to do to give the connection alive ? Need to send something over it to keep it alive ?

Thanks.

Not sure why you want to have chatting app to have persisted connection... I'd better use SMS like model. Anyways, Cocoa NSStream is based on NSSocket and allows a lot of functionality. Take a look at it.

Response to the question. Here is in a nutshell, what I would do:

1. Get an authentication token from the server.
   • this will also take care of user presence if necessary but now we are talking about the state; once presence is known, the server may send out notifications to clients that are active and have a user on their contact list.
2. Get user's contact list and contact presence state.
3. When a message send, handle it according to addressee state, i.e. if online, communicate back to the other user, if offline, queue for later delivery or reject.
4. Once token expires, reject communication with appropriate error and make the client to request a new token.

Communication from server to client, can be based on pull or push model. In first case, client periodically makes a request and fetches all messages. This may sound not good but in reality, how often users compose and send messages? Several times a minute? That's not too much. So fetching may happen every 5-10 seconds.

For push model, client must be able to listen and accept connections.

Finally, check out SIP, session initiation protocol. No need to use full version of it though. Just basic stuff.

This is very rough and perhaps simplified. I don't know the target complexity of your chatting system. For example, the simplest thing can also be that server just enables client to client communication by distributing their end points and clients take care of everything themselves.

Good luck!

Super out of date response, but maybe it will help the next person.

I would use xmppframework and a jabber server.