+1 for GRDB. One of the best open source iOS SDKs I've used. The one downside I've run into vs. Core Data is that sharing a database between multiple processes

+1 for GRDB. One of the best open source iOS SDKs I've used. The one downside I've run into vs. Core Data is that sharing a database between multiple processes (e.g., your main app and a widget) is not as well supported (to be fair, the quirks around this are documented extensively and quite well).