I get it now. You also could use [object class] instead of an arbitrary static pointer. I never had issue with a class and a subclass using the same observer

I get it now. You also could use [object class] instead of an arbitrary static pointer. I never had issue with a class and a subclass using the same observer keypath. Whenever I use it I always call super to make sure everything underneath is called. But that's a good thing to know for sure, thanks.