How to create nested folders on iOS 7
Nested folders (or, folders within folders) are one of the most useful features of iOS 7. Unfortunately, it's more of a glitch than anything Apple intended to include, so there's no official guide from Apple on how to do it. But don't worry; we're here to help.
via Pocket http://www.tuaw.com/2013/09/24/how-to-create-nested-folders-on-ios-7/