Default Data flow in app

Hello Everybody,

My friend and I for the past month thinking about application development project.
We have a good idea for app and we think a lot about how we going to develop this app,
We both have knowledge at Xcode and Objective-C but we don't know what we need for our app-

the app is based on transfer of information(data),I don't want to tell exactly on what the app deals but I can tell that the app should be able to absorb data and sending data and here is the problem-We dont know how we can to transfer data.
let's say that we want chat on our app,like Facebook or Whatsapp,how we can do that?
We tried to use Framework that called Parse-for people that don't know,Parse give you a kind of a "server" that you can transfer data in it but the problem is that if app want to get data from the server we only succeeded to do that the app every short time(2 seconds for example)do "refresh" and cheack if there is a update at the serever,but this way it isn't good way because this is overload on the server and the iPhone.
We are desperate for help-if there is anyone who know how to send and absorb data for and from server in efficient way.


I hope you understand the problem and will be able to help us
thank you very much
Tomer

PS
I new in this forum,sorry if I broke the forums ruls,
I have not found better place to post it.