June 2015 - last edited September 2015
-: Updated September 2015 :-
There are now fixes for the non compatible graphics - http://bluebellflora.com/fix-for-incompatible-graphics-for-the-sims-3-on-mac/
Not really sure where I should be posting this but this is a problem that doesn't seem to be going away any time soon.
If you have a 13" retina MacBook Pro or an entry level 15" MacBook Pro with Intel Iris graphics it is highly unlikely that you will be able to get TS3 to work. This is because EA have never released a patch to support these integrated graphics. For more info please read my article here:
You can try the workaround here (thanks to tmethei):
Using CC/Mods is at your own risk, EA are not responsible for making the game compatible with 3rd party content, the creator is.