My recommendation is to go your way through the docs at http://developer.apple.com . There is plenty of useful material from the manual to the sample code.
Regarding the creation of graphical applications, I would recommend creating parts of the graphical interface using Cocoa (Objective-C). You can still implement your logic and other applications using C ++ (C ++ and Objective-C work together). However, Cocoa is much easier to work than the older Cobal based on C ++. I believe carbon will be a legacy. When the apple released 10.6, many things under the hood moved their code base from Carbon to Cocoa (e.g. Finder, etc.).
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