XCode 4 downloads mac os x 10.6 core library?

Well, I j开发者_运维百科ust got XCode 4, and at some point it starts downloading something called Mac OSX 10.6 core library. What is that, and why?

It's the documentation from Apple for Mac OS X, all of the class references, etc. With it, you can look up different information about every class that Apple offers you (like if you wanted to learn more about the methods in the NSString class).

You can manually download & extract all the Xcode 4 documentation, by getting the links & instructions here: http://learning2code.blogspot.com/2008/05/download-xcode-docsets-to-your-hard.html