NSManagedObjectContextObjectsDidChangeNotification for one entity

Question

It's possible with NSManagedObjectContextObjectsDidChangeNotification to get a notification only when a specific entity changes?

I want to update my view when my contact information or avatar changes, but with NSManagedObjectContextObjectsDidChangeNotification I'm getting a notification every time something gets changed on the database.

It's possible to do that with NSManagedObjectContextObjectsDidChangeNotification?

Answer 1

I don't believe it is possible to have it only trigger for a specific entity. However, the notification does provide information on which objects were changed. The notification contains a dictionary (userInfo) which contains 3 keys:

• NSDeletedObjectsKey - array of all objects that have been deleted
• NSInsertedObjectsKey - array of all objects that have been added/inserted
• NSUpdatedObjectsKey - array of all objects that have been modified

You can iterate over the contents of those arrays and determine if your particular object has been changed. A rough outline is below:

- (void) handleObjectsChangedNotification:(NSNotification*) notification {
    // Iterate over all of the deleted objects
    for (NSManagedObject* object in notification.userInfo[NSDeletedObjectsKey]) {
    }

    // Iterate over all of the new objects
    for (NSManagedObject* object in notification.userInfo[NSInsertedObjectsKey]) {
    }

    // Iterate over all of the modified objects
    for (NSManagedObject* object in notification.userInfo[NSUpdatedObjectsKey]) {
    }
}