Learning Core Data for iOS: A Hands-On Guide to Building Core Data Applications

De-Duplication

When iCloud is used across multiple devices, there’s a risk that duplicate items may be created by the user or seeded to iCloud. In particular, when an item is created on an offline device, it won’t appear on other devices until Internet connectivity is restored. In the meantime, if an item with the same name is created on another device, then duplicate items will result. To deal with this scenario, a new Deduplicator class will be used to selectively delete the oldest of the duplicate items. In your own applications, you may wish to add other logic to determine the most appropriate duplicate to delete. For example, you may wish to compare attribute values such as a NSUUID or even take into account relationships before choosing ...