Last year iOS 8 introduced iCloud Drive, which works very similarly to Dropbox without the file sharing function. In other words, it allows you to easily sync all of your files to all of the devices you own but doesn’t facilitate sharing them with third parties. But in order to manipulate the files in your iCloud Drive you had to do that on OS X Yosemite or by using a third-party iOS app which could be clunky.
But iOS 9 added a built-in file manager for your mobile devices. Think of it as Finder for iOS. To enable it, visit Settings > iCloud > iCloud Drive, and flip the switch on for “Show on Home Screen“. This adds an iCloud Drive icon to your home screen alongside your other apps.