A Microsoft file hosting and synchronization service.
Hi Em,
As per checking, on the iPhone/iPad, SwiftKey can connect to OneDrive to back up your keyboard dictionary and settings regardless if you don’t have the OneDrive app installed, SwiftKey itself will still prompt you to use OneDrive for backup. That’s why you keep seeing the message.
However, in order to stop the prompt, you can disable Backup & Sync in SwiftKey settings and sign out of your Microsoft account inside SwiftKey. That way, SwiftKey won’t try to use OneDrive at all, and you can keep using the keyboard without interruptions.