KOTree allows you to show a tree of hierarchical data, e.g. files and folders. It was developed for Kodiak PHP, an app which allows you to write and run PHP code directly on the iPad. The items can be expanded and collapsed by tapping them. An item can be selected by tapping its icon.
To see the component in action, take a look at the video at http://www.becomekodiak.com/ or try our app called Kodiak PHP on the App Store.