That's not true. Everything they have on the iPhone comes from Mac OS X. They simply just had to fix some issues related to the "embedded" word (better power manager, touch input and so on). But everything else comes from Mac OS X. And they are working on Mac OS X more than Nokia on Linux+GTK. Moreover, they are for sure working, internally, on the iPhone a lot more earlier than one year. Like they did for Mac OS X on Intel. They said, later, that they were working on it since 2000. Last, Cocoa stems from Carbon. Carbon comes from NeXT (still Steve, but running a darker company).