I'm going to assume you are talking about iCloud when you say cloud. I don't use iCloud myself. There are apps on my iPhone that use the iCloud for stuff, but I don't use the iCloud for storage like a flash drive. I do use dropbox and googledrive (just other cloud services) instead of a flash drive.
With the dropbox app on my iphone I can mark stuff in my dropbox so it gets stored on my iPhone. Then it does not have to be downloaded each and every time I want to view it. Other then playing around with that feature I don't really use it because I always have a cell phone connection, or at least about 99% of the time.