In Apple's Document Based App Development Guide, it emphasizes that our app should let users choose either to save all their files to iCloud or save all on local device. Is there reason for this? Can we actually allow users to pick some files to be saved on iCloud and some to be saved locally, like the TextEdit app on mac OS X? Will App Store disapprove iOS apps configured in this way if it is programmatically possible?
Thanks!
If it makes sense for your app, there is no reason Apple would care if you save some files locally and some in iCloud. It's not a hard fast rule to be all one way or the other.