Ask HN: Core data and iCloud or external database for iOS app storage?

One of the best benefits I can think of favoring Core Data and iCloud/CloudKit is the very public stance Apple has taken on privacy.

One largest downsides I can think of is vendor lock-in. If you intend to expand beyond iOS, there will be some friction and a great deal of re-implementation once you select another platform to build on.

If you do intend to move on to other platforms, I'm impressed by Realm's offerings [1]. The support local data storage, as well as syncing to their cloud platform (with a monthly fee, of course).

EDIT: Forgot to include the [1] link.

[1] https://realm.io/

The other downside to core data + iCloud is that you yourself have no access to the data. That means that if you want to email your users or even just pull aggregate data about their usage, you're crippled.

You also don't have a database that you can use to provide data to your users or let them provide information to one another.