Prior to iThoughts v6 (on iOS) the app used to manage the process of keeping your maps on iOS synced with the cloud’ (eg Dropbox, iCloud or WebDAV.) This was quite complex to administer - but really quite powerful. You can still read all about it here. Indeed the app still supports this approach if you disable the Files interface (in the iThoughts System Settings.)
Version 6 and later now uses the built in Files app to manage access to maps stored in the cloud (and the syncing thereof.) From a user’s perspective, you just open a map in the cloud - there is no obvious syncing required. This works because Apple now have technology in iOS that lets people like Dropbox and OneDrive ‘plug in’ to the iOS File Picker. See below for a badly drawn diagram of the pieces involved.
This has a number of upsides:
iThoughts will automatically support ALL cloud services (that choose to implement a plugin.) No work on my part :-)
Consistent user interface (no more complex syncing to setup.)
But as with all upsides, there are the inevitable downsides:
When things go wrong, you are on your own (or at least you need to speak to Apple/Dropbox etc.) I can’t help debug the situation since everything in the diagram above that isn’t orange is not visible to me
Only .itmz files can be EDITED (although it is still possible to import other formats and convert then to .itmz)
NB: Most cloud providers have a files plugin - but for those that don’t (eg WebDAV) there is an app that can help - see FileBrowser.
NB2: The GDrive plugin from Google doesn’t work but the FileBrowser app above will plug into Google and it does work.