Hey guys so we had quite a lot of requests from projects who wanted to implement server-side chat history so you could sync it between different devices and platforms of your users. Our standard answer was you could use Custom Objects for that but obviously that required additional API call from the client-side so was not the best possible solution. So we have decided we create a server-side bridge between Chat and Custom Objects effectively allowing you to manipulate your chat history as if it was your Custom Objects data object without having to do any extra work on the client side.
This feature is now supported as explained in our Developers section article Chat: handling chat history API.
Good news it is now also natively supported in our iOS SDK 1.8. For Android and Web users you may use Custom Objects API to access chat history and we will add even easier integration in the nearest future.