I've never found a consistently better OO API than Cocoa (that survived any amount of time). It's a great evolution of the NeXTStep frameworks, which were ment

I've never found a consistently better OO API than Cocoa (that survived any amount of time). It's a great evolution of the NeXTStep frameworks, which were mentioned all over the GoF book. You can tell a lot of care goes into that API.