Hello. I have a tableview whose content is bound to an NSArrayController's arrangedObjects (nothing fancy here). The objects populating the table are entities with many attributes. The controllers is bound to a managed object context. I want to observe changes in the controller's arrangedObjects property. Every time I interact with the table in a way that should alter the property (filtering rows, sorting), it appears that this property is changed many times in a row. Like 13 to 20 times when I sort the view by clicking on a column header or when I add a new object to the controller's content. I cannot predict the number of time the property is going to be changed. It doesn't appear to be related with the number of objects populating the view. Note that the app behaves normally. In fact, I haven't noticed anything special before I decided to observe the property. It doesn't happen to other views that are populated by "simpler" entities with fewer attributes, and bound to other controllers. The arrangedObjects property is changed just once. Any ideas?