Core Data 'modified' timestamp

Question

I'm trying to set up an automatic 'modified' timestamp with my Core Data object graph. I've got it working within each model with the following code:

- (void)willSave
{
    NSDate *date = [NSDate date];
    [self setPrimitiveValue:date forKey:@"modified"];
    [super willSave];
}

However, I'd like this modified date to be able to bubble up the object graph, changing the modified date for each parent object in turn.

So if I have: Grandparent--(hasMany)-->>Parent--(hasMany)-->>Child and I change a property of Child, the Parent and Grandparent modified timestamps should all update to the same value.

Is there a simple way to do this? Thanks!

Answer 1

You may register for the NSManagedObjectContextObjectsDidChangeNotification notification. In it's userInfo, you get a list of updated, deleted, and inserted managed objects.

Next step would be to iterate over the inserted and updated objects, then introspect objects (isKindOfClass, respondsToSelector, ...) and assign a timestamp on picked objects.

Best,