Is there a cloud IDE with access to its virtual machine via FTP, WebDAV or Dropbox?

Question

FTP

Cloud IDEs such as Cloud9, Koding, or Codeanywhere are great for for-fun development. There is a convenient editor and a virtual server with everything you need to execute the code, including the database. But there is one small snag - sometimes you want to work in some other IDE and quickly transfer files. For a tablet, for example, from the listed ones, there is a client only from Codeanywhere, but it is extremely buggy and inconvenient to use. It also works only online, and if it falls offline, the work is lost. At the same time, there are many convenient iOS editors with sFTP/FTP/Dropbox support: Textastic, Koder, Diet Coda.
Is it possible to set up sFTP/FTP/Dropbox access to any cloud IDE? They themselves easily cling to other sites via FTP, but I did not find information on how to access files from the FTP client in the online IDE.