ECSlidingViewController is a nice implementation of a common UI construct wherein a user can swipe either left or right to expose a view underneath. Most commonly this is used to display a menu of options.
Mike Enriquez sums up the design and code implementation as follows:
The philosophy behind ECSlidingViewController is to provide simple defaults while being customizable. It may not work or look the way you want out of the box, but it doesn’t get in the way when customizing it.
A good approach to API development, nothing more frustrating than fighting with a tool that’s intended to help.