Question

I have an entity with several properties, one of them called lastModificationDate. Whenever any of the object’s properties is set, I’d like to update the lastModificationDate.

If I were not using Core Data, I would just provide my own setter for the properties and update lastModificationDate. However, I’m not sure if I should mess around with CoreData’s properties.

What’s the best way to do this?

Answer 1

Overriding the setters can easily be done, you have to make sure you fire the right notifications for everything else to work (including KVO).

- (void) setThing:(NSObject *)myThing {
  self.lastUpdateDate = [NSDate date];
  [self willChangeValueForKey:@"thing"];
  [self setPrimitiveThing:myThing];
  [self didChangeValueForKey:@"thing"];
}

This being said, if all you need to do is the code I showed (essentially setting the value and updating the last update date), you are much better off using Key-Value Observing and reacting to the notifications. It’s easier and cleaner.