nscountedset

KVO on an NSCountedSet?

I'd like to monitor an NSCountedSet to see if its contents changes. Setting up KVO seems to compile but it's not being triggered. First question: can you observe a set? If so then is there something wrong with this message? [subViewA addObserver:subViewB forKeyPath:@"countedSet" options:0 context:NULL]; I'm really just trying to m...