<!--
{
  "documentType" : "article",
  "framework" : "CoreData",
  "identifier" : "/documentation/CoreData/notification-keys",
  "metadataVersion" : "0.1.0",
  "role" : "collectionGroup",
  "title" : "Notification keys"
}
-->

# Notification keys

The keys you use to retrieve values from a notification’s user info dictionary.

## Topics

### Constants

[`let NSAddedPersistentStoresKey: String`](/documentation/CoreData/NSAddedPersistentStoresKey)

Key for the array of stores that were added.

[`let NSRemovedPersistentStoresKey: String`](/documentation/CoreData/NSRemovedPersistentStoresKey)

Key for the array of stores that were removed.

[`let NSUUIDChangedPersistentStoresKey: String`](/documentation/CoreData/NSUUIDChangedPersistentStoresKey)

Key for an array containing the old and new stores.

[`let NSPersistentStoreConnectionPoolMaxSizeKey: String`](/documentation/CoreData/NSPersistentStoreConnectionPoolMaxSizeKey)

The maximum connection pool size to use on a store that supports concurrent request handling.

[`let NSPersistentStoreSaveConflictsErrorKey: String`](/documentation/CoreData/NSPersistentStoreSaveConflictsErrorKey)

The key for the array of merge conflict objects (instances of [`NSMergeConflict`](/documentation/CoreData/NSMergeConflict)).

[`let NSPersistentStoreUbiquitousTransitionTypeKey: String`](/documentation/CoreData/NSPersistentStoreUbiquitousTransitionTypeKey)


---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)