Apple's Enterprise Objects Framework uses a category to add an addObjectIfAbsent: method to NSMutableArray:
@interface NSMutableArray (EOPointerBasedManipulation)
- (BOOL)addObjectIfAbsent:object;
// adds an object to the array if and only if it isn't already in the array
// return YES if object was not in the array or NO if it already was present
@end
Because this method is not documented, some Apple developers and writers of third-party frameworks have added their own addObjectIfAbsent: method. When EOF's EOObjectStoreCoordinator makes a call to addObjectIfAbsent: to register a notification, it does not receive the expected return value, and two additional notifications are generated. This can seriously affect system performance in applications which make a large number of database fetches. There are three possible solutions to the problem:
--Modify your implementation of the method to return the appropriate values, as shown above
--Modify your code to use Apple's implementation of this method
--Change the name of your custom method so Apple's implementation is not superceded.