IOS implementation of simple messaging system (client/server) between clients

Question

i've been looking around to find a simple library or a client/server sample code for implementing a messaging system between users of my IOS clients app and a REST server. I would need that each user has an incoming and sent messages view. This view would display the conversations grouped by user. For example, using a table view where each cell represent a thread between the 2 distinct users, selecting a user's conversation it would push a new view that would display all the messages between the two users.

I have to say that i didn't found much, this is a mix of libraries and front ends:

• an XMPP objective-c library: https://github.com/robbiehanson/XMPPFramework, but i don't really want an IM behavior
• Acani chat, https://github.com/acani/AcaniChat seems promising but waiting for the acani chat server, i could use the front end
• another chat https://github.com/honcheng/iOS-nodechat
• MailCore, an IMAP api for objective-c: https://github.com/mronge/mailcore . i would need to relay on a mail server, create emails for each user and ... too much!
• too bad there isn't any iMessage API
• dont want to send a SMS or an email
• push notification it's not a must to start

maybe coding a simple REST service for publishing and retrieving messages to and from a user would be the best approach? i'm i missing something?

thanks!!