Q:

Is there anyway to use Facebook v2.6 API instead of latest v3.0 API?

There are certain API rate limits applied on Facebook v2.7 onwards. Is there anyway I can revert back to v2.6?

A:

You can't use a deprecated API. There is no way you can use API v2.6 now.
The only possible way would be to get an old app that was created using API v2.6.

