In contrast to Polynomial's suggestion, I don't like exporting to DropBox or Email, since most end users use 3rd party applications that have access to the entire datastore using linked apps.
DropBox in particular makes it too easy for an app to gain full access to the entire storage (keys and everything).
I am presently leaning towards iCloud, where no other application has the ability to read the data I save in private storage. It took me a minute to understand this technology, where each iOS application gets its own container.
A per-application container consists of
- One public database they can read/write to
- One private database per iCloud user
Generally speaking there is only one container per application, meaning that each iOS application is isolated from each other.
In addition, the developer can't directly read the contents of a user's iCloud database. This is a feature that DropBox OAuth, and other commodity storage doesn't have.
(not to mention, it's almost free)
That being said, I would still encrypt as Polynomial suggests, no matter where it goes.