According to the docs, NSNotificationCenter already was present in Mac OS X 10.0. It seems to be present in NextSTEP 3.3, which was released in 1995 (http://www

According to the docs, NSNotificationCenter already was present in Mac OS X 10.0. It seems to be present in NextSTEP 3.3, which was released in 1995 (http://www.cilinder.be/docs/next/NeXTStep/3.3/nd/Foundation/Classes/NSNotificationCenter.htmld/index.html http://www.cilinder.be/docs/next/NeXTStep/3.3/nd/Foundation/...).