Apple has won two US patents on the iOS folder system. The first is titled Device, method, and graphical user interface for managing folders
, and specifically documents
the way iOS users can create folders by tapping and holding an app icon, which triggers a "jiggle mode" that lets people rearrange apps. Dragging one app on top of another puts the two items into a new folder. Alternately, tapping X on an icon lets people remove an app from a device entirely, and icons can be dragged out of existing folders.
One patent concept that hasn't made it into a release version of iOS is the "folder creation region." This would let people create folders either by tapping on a given region of a screen, or else by dragging a folder into that space. Apple may have rejected the idea as unnecessary, confusing, and/or a waste of screen room.
The patent dates back to September 2010, and is credited to Imran Chaudhri. Apple debuted iOS folders with 2010's iOS 4, and has made very few changes to the system since. The other patent is in fact also credited to Chaudhri, and simply covers the design of the screen-splitting animation seen when opening a folder.