Think of sessions as rooms. People connected to the same session will be in the same room so they are able to see each other. Lets say you have 2 iPhones, A and B. After iPhone A calls [_session publish...]
, iPhone B will get a stream created event with A's video stream. Simply subscribe to that stream and B should be able to see As video.
You probably want to have a streamCreated delegate. In your streamCreated delegate, simply call [session subscribe...]
to subscribe to the publishing stream.
For an example, check out the OpenTok HelloWorld Tutorial. Its a simple group video chat where everybody is publishing and subscribing to each other.