>old api Carbon, is gone now only Cocoa remains.
Since when? Apple dropped their plans to update carbon to 64 bit and they are no longer adding new features to the API but it still exists and they still release patches for it. If they dropped carbon completely there would be a lot of major applications that would not run. Adobe Fireworks and MS Office come to mind as applications I use frequently which are still largely carbon.
1.79 x 10^12 furlongs per fortnight -- it's not just a good idea, it's the law!