Possible Duplicate:
Adding syntax highlighting to programming languages in Xcode 4.0
Is it possible to make xCode4 to do syntax highlighting on .lua files? There are plenty solutions online for xCode 3.2, but I've found none for xCode4.
According to this site, the old XCode 3 syntax highlighting plugins were based on an unofficial and unsupported API. XCode 4 is a complete rewrite of XCode, so it's unlikely that API exists any more, and to my knowledge no-one has yet discovered any similar API, so it looks like you may be out of luck.
The good news is that XCode does play quite well with external editors (Of which there are quite a few which do Lua), and any changes you make in an external editor are instantly reflected in XCode.