So, supposing Dropbox has a sync with the files api, then that sync would be the responsibility (and implemented by) the Dropbox app. All you need to is ensure that you write into Files api properly (Ie don’t leave any locks around on files, etc - I’m not an iOS developer so I have no idea what’s actually required for very good/correct Files api interoperation, but it should be in Apple docs).

With a git repo program like Working Copy, you’d just write into its Files space (same as above for Dropbox), then Working Copy handles the syncing. Since Working Copy has no such auto sync as something like Dropbox would have, since WC is a git repo app and not a cloud files service, the user would manually open it themselves and make a commit and push it at their own choosing. Any writes to WC in the meantime will just overwrite. That’s all understood by the user , if he’s using a git repo as his files backup. I prefer manually syncing my files as commits to a repo, so this all works beautifully for me .

I don’t like placing the security of my synchronization in the hands of cloud files providers such as Dropbox or Google Drive. I use multiple iPads and laptops at once, so google drive and Dropbox bugs in sync may bite me. For notes this is best for me, since note update frequency of one to five times an hour doesn’t need any auto sync. But most users, even programmers, that I know don’t seem to enjoy this level of exactness.