[nglevin]

Just one nitpick for an excellent comment. GNUstep/Clang would be the only way to get support for array, dictionary and number literals, as well as ARC.

GNUstep/GCC is possible, but you lose support for all of the above, blocks, and several other recent additions to the Objective-C language.

[rubymaverick]

Very true. We really leaned heavily on the new literals and ARC in this course.