Coda ships with syntax highlighting support for a lot of great languages, but some are noticeably left out of the mix. I was recently helping a buddy set up an environment to develop C programs on an external server, and while Coda seemed a clear better alternative to using Nano (particularly since we could still compile and run the programs from Coda’s built-in terminal), the program lacked syntax highlighting for the C language.
Adding highlighting for C (and a host of other languages) turned out to be pretty easy.
To add support for other languages, download this zip file, unzip, and copy the Modes folder into Contents > Resources of the Coda package distribution. To access the contents of the package, right click on the Coda application and select “Show Package Contents”. Then navigate to Contents > Resources.
If you are asked, overwrite existing folders and files. Note that if you only want to install certain syntax highlighting modes, just copy and paste what you need (of the .mode files in the downloaded Modes folder) into the Modes folder in the Coda package. I forgot which languages were standard to Coda so I’ve just included all of the ones I have in the download.