In theory one should be able to do these exercises with OS X 10.6 and Xcode 4.2, while ARC is mostly available in this configuration, it looks like some code changes are required. For example, instead of using “weak” one has to use “unsafe_retained”. I am also getting linking errors “ld: file not found: /Developer/usr/lib/arc/libarclite_macosx.a”, which suggests that OS X 10.6 does not have all that is necessary for the exercises to work. The options are
- use manual reference counting (an interesting exercise)
- upgrade to Lion
- try to get it to work with ARC.
Is option 3 possible?