Functionally it's primitive: you have left-view in background, and there's drag gesture recognizer, which "catches" foreground view and moves it on xz-direction.
There are lots of open source implementations for ios:
But there was a problem related to storyboards: there's no out-of-box solution to integrate left-side menu with storyboards power! Recently I found really easy to use framework: ViewDeckStoryBoards. Hooray, there's no need to revert back to xibs nightmare! It's based on viewDeck, there's a little code needed(just to overwrite left side & main windows). It supports arc, storyboards.