Facebook's Platform supports both versioning and migrations so that app builders can roll out changes over time.
Goal of versioning:
The goal for having versioning is for developers building apps to be able to understand in advance when an API or SDK might change. They help with web development, but are critical with mobile development because a person using your app on their phone may take a long time to upgrade (or may never upgrade).
Faecbook recommends to use graph-api version 2:
Older versions of Facebook's API will expire April 30, 2015 and there are some significant changes between the older versions and the latest version. It is highly recommend to start building for Graph API v2.0+ to make sure that people's experience with apps will not be affected when the older API expires.
Upgrading to graph-api version 2 using 'fbgraph' gem:
FbGraph::v2! # Use version v2 for fbgraph
[fbgraph2 gem] supports graph-api version 2 by default.
[facebook api upgrading]
[how facebook versions work?]