Core Data is an object-graph persistence framework, not a database. As said in the other comment, Core Data is an implementation detail, and there are other bac

Core Data is an object-graph persistence framework, not a database. As said in the other comment, Core Data is an implementation detail, and there are other backends to choose from. Apple adds additional metadata on top of the entities themselves in order to provide smart versioning and migration utilities. The entire object model is persisted inside the database, so that lightweight and heavyweight migration patterns can be deduced the next time the database is read. This metadata can also assist with opening WhatsApp's database and parsing it using Core Data.