I am a beginner of Mac computer. But I could managed to build OsiriX on Xcode 4.3 from the source codes .
So, I’ll give you some tips.
#1 Xcode 4.3 can use subversion (SVN) directly. It’s easier for the beginners to get the OsiriX source code from ‘repository’. (NO NEED to use ‘terminal’)
#2 Xcode 4.3 disregards ‘target’ concept and adopts ’scheme’ concept in order to build ‘product’ or ‘library’. You should set it up by selecting your desirable item using ‘Scheme’ selection box on the topleft of the panel.