Core Data: lightweight migration

Hi everyone,

I’m working on an offline-first iOS app using Core Data.

I have a question about safe future updates: in my project, I want to be able to add new optional fields to existing Entities or even completely new Entities in future versions — but nothing else (no renaming, deleting, or type changes).

Here’s how my current PersistenceController looks:

import CoreData

struct PersistenceController {
    static let shared = PersistenceController()

    let container: NSPersistentContainer

    init(inMemory: Bool = false) {
        container = NSPersistentContainer(name: "MyApp")
        if inMemory {
            container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
        }
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                print("Core Data failed to load store: \(error), \(error.userInfo)")
            }
        })
        container.viewContext.automaticallyMergesChangesFromParent = true
    }
}

Do I need to explicitly set these properties to ensure lightweight migration works?

shouldMigrateStoreAutomatically = true shouldInferMappingModelAutomatically = true

Or, according to the documentation, are they already true by default, so I can safely add optional fields and new Entities in future versions without breaking users’ existing data?

Thanks in advance for your guidance!