LiveSessions is a sample iOS app that allows geographically nearby app users to have two way video chat. 

The user management is done by Parse.com database, and video streaming is taken care of by tokbox.com platform.

For detailed usage and guidelines, visit this tutorial:
http://www.iphonegamezone.net/ios-tutorial-create-iphone-video-chat-app-using-parse-and-opentok-tokbox/