How to Migrate Your Apps to Sync with iCloud

iCloud is a fantastic way to sync users’ data across all their devices, such as iPhone, iPad, and Apple Watch. Recently, I successfully migrated one of my apps from local data storage to iCloud. In this article, I will guide you through the process and highlight important considerations along the way.

Assumptions

This guide assumes you already have Core Data set up in your project.

Overview of the Process

1. Ensure all attributes for entities are optional.
2. Add iCloud capabilities to the targets you want to sync with iCloud.
3. Use NSPersistentCloudKitContainer.
4. Test in Development mode.
5. Migrate the schema to Production.
6. Test with TestFlight.
7. Release your app.

Proccess in Detail

Step 1: Make All Attributes Optional

Ensure that all attributes for entities in your Core Data model are marked as optional. This is crucial because CloudKit doesn’t support required attributes directly. Skipping this step may result in synchronization issues or crashes.

If you have attributes previously defined as required, I suggest you change them to optional first, release a version of the app, and verify your users have migrated successfully. In general, this should work…