Facebook guys have done brilliant job in the new version of the app. The similar open source code can be found from here – JTRevealSidebarDemo. Please note that as of June 2014, this project has been discontinued, so you’ll probably have better luck with a project from the list below.
It reveals technique behind doing split view for iPhone.
Edit: Few other open source codes:
- JWSlideMenu
- DDMenuController
- PKRevealController
- ViewDeck
- ECSlidingViewController
- MWFSlideNavigationViewController
- MFSideMenu
- SASlideMenu
- HHTabListController
- MTSlideViewController
- MTStackViewController
- MMDrawerController
- DMSideMenuController
- JVFloatingDrawer