Hi, on my iPhone 6s+, I can drag one app over the other to create a folder. However, I cannot drag a folder into another folder. http://www.techbout.com/create-nested-folders-in-ios-9-4412/ presented two methods but they both revert to normal after a reboot. Is there a way to create sub-folders permanently under iOS 9.2.1? Why such feature is not included in iOS?