cocoa - How can I determine the running Mac OS X version programmatically?

Question

I have a program which needs to behave slightly differently on Tiger than on Leopard. Does anybody know of a system call which will allow me to accurately determine which version of Mac OS X I am running. I have found a number of macro definitions to determine the OS of the build machine, but nothing really good to determine the OS of the running machine.

Thanks, Joe

Answer 1

See this article here

But in short, if you're using carbon, use the Gestalt() call, and if you're using cocoa, there is a constant called NSAppKitVersionNumber which you can simply check against.

Edit: For Mac OSX 10.8 and above, don't use Gestalt() anymore. See this answer for more details: How do I determine the OS version at runtime in OS X or iOS (without using Gestalt)?