All I see is Windows and Linux support only, why is there no guide for mining ether on a Mac? Is there a way to mine on a Mac?
Well, there are no guides because mining on a Mac is really ineffective, even on a Mac Pro.
However, it's pretty easy – all you need is
brew tap ethereum/ethereum brew install cpp-ethereum
ethminer -G -F http://somepool.com
Mining on a Mac is not really worthwhile. In fact mining on your own on any Desktop computer is not really worthwhile. Your costs (electricity, hardware wear etc) are greater than what you earn.
Over on the Ethereum forum, user 'bluebox' provides some additional insight including:
If your GTX780M has 2GB, it's possible but not going to be very good (low, low hash rate). The DAG file (1.4GB) has to fit entirely in GPU memory, even so the 7xx series won't mine too well. 3-4GB GPU RAM is minimum these days. Yes, you probably could mine on it, just don't expect much. And don't let anybody tell you it will "melt" — you can't hurt it, but just remember heat over time shortens the life of all silicon-based lifeforms. SMCFanControl still works on El Cap, so you can crank the fans up.
Essentially it will depend exactly what Mac you have, and what hardware it has but it is generally not worthwhile.
If you want to mine, you should probably consider a pool.