> Core Data and SwiftData Migration Checklist
// A checklist for Core Data schema migrations and SwiftData adoption — covering model versioning, lightweight vs custom migration, testing with real data, and keeping users safe through the transition.
Core Data migrations are one of the few places where a code change can directly destroy user data if something goes wrong. The most common cause is not the migration logic itself — it's an incomplete migration chain that does not account for users who skipped several versions and are migrating from a much older schema.
The testing section is the most important part of this checklist. Running the migration against a store seeded with real data from the old model version, rather than a freshly created store, will surface issues that schema validation misses.