Possible app rejection by syncing zipped sqlite database in iOS
Well, strictly that link is talking about syncing a sqlite database on iCloud. You say you're wanting to backup. IF you don't need different devices to have the ability to edit the same database file you might be ok.
However, if you need different devices to have edit access to the 'same' database file (syncing), then it's not possible to use sqlite to do this on iCloud by uploading the actual database file - you will end up with a corrupt database.
You would have to implement your own transaction logging system - where you keep separate databases on each device, and your log files are used to keep them all in sync with each other. This is actually what Apple does for their Core Data syncing solution - the databases only exist on the devices, not in iCloud - only the transaction log files get uploaded to iCloud.
Does anyone know if someone has invented a solution to do this already? It shouldn't be outside the realms of possibility...
Actually, this answers pretty much the same thing I've just done...