Register an observer with something like:[searchArrayController addObserver: self forKeyPath: @"selectionIndexes" options: NSKeyValueObservingOptionNew context: NULL];This makesself
an observer of thesearchArrayController
. We'll get notified when theselectionIndexes
value changes, and we'll be notified with the new value.When the notification happens, this method (invoked against the
self
used earlier) is invoked:- (void) observeValueForKeyPath: (NSString *) keyPath ofObject: (id) object change: (NSDictionary *) change context: (void *) context { } // observeValueForKeyPathand you can poke around the arguments to see wha'happened.