Thank you very much for your reply. Am I right in understanding that, I could leave the Mac project open on standby, while editing it on iOS, and as long as I sync it back before starting to work on the Mac project again, it will be fine?
Since you are using the Dropbox client on the Mac, you don’t really need to do anything on that side, other than wait for it to finish syncing your changes before switching devices—it’s all automatic and works continuously in the background as you work in the project. So you don’t have to click a button or use a menu command to sync, like you would with the external folder feature. Not having to sync, as an action, is the whole advantage of putting the whole project you are working on into the Dropbox folder; same as for everything else you might choose to save into that folder.
That kind of convenience isn’t available on iOS given the system’s design, so you do have to sync there, however there are some settings you can change to make things less of a procedure. Go into the system Settings.app tool and scroll down to Scrivener’s settings. Under “Syncing & Sharing” you can set it up to always sync automatically when you close the project, and to check whenever you open a project. With both of those set, you won’t ever have to remember to do anything, it will always ask if necessary, or just automatically sync for you.
You do want to close out the project on mobile whenever you switch back.
Give it a quick test with the tutorial project or something equally disposable. You should find it’s quite easy to manage once you’ve seen how it works a time or two.