When Apple announced at WWDC 2006 that full 64-bit support was coming in Leopard, the message was that it would be supported in both Carbon and Cocoa. Now it’s Cocoa-only. As Michael Tsai mentions, this matters even for developers writing Cocoa apps:
All of my applications are Cocoa, but they use bits of Carbon to do things that aren’t possible with pure Cocoa.
★ Wednesday, 13 June 2007