Moving the other way, I found that the skills that are being transferred are just low-level material such as Objective-C, Foundation, and Core Foundation, and the tools are the same.
Also, many low-level concepts are the same. There are more tasks and activities, IBOutlets and IBActions. However, at a higher level, everything is very different. There is, for example, a table view, but you tend to use it differently and only when the actual table is required, and not as the basis for the entire GUI idiom. In addition, table views have more than one column.
There are many advantages, for example, you have much more freedom in what your user interface will look like. And you use garbage collection. With GC, everything you learn about Cocoa's memory management becomes instantly redundant. It is very liberating.
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