facebook/facebook-ios-sdk — pull request #450 by nov (2012-04-13 10:42:49+00:00)
Title: Handle authentication code too

For applications which uses Graph API for server-side authentication.
Sending access token from client to server for server-side authentication causes a big security hole.
ref) http://www.thread-safe.com/2012/02/more-on-oauth-implicit-flow-application.html