SimGuruDrake has just confirmed that the Sims 3 team are apparently still looking into the incompatibility issue on post-2013 Macs and unsupported graphics cards, notably all Intel Iris and most Intel HD integrated chipsets:
http://forums.thesims.com/en_US/discussion/comment/14453811/#Comment_14453811
Let's hope they really are looking into it as it is affecting such a huge amount of Mac Simmers.
Comments
Add Manage Neighbourhood Options - assign your own Sim to NPC jobs!
The Problems with Death in The Sims 4
Distinguish Elder gameplay with Elder-only reward traits
Filter Rugs by Room Size
Have you tried editing the sgr files as recommended? I wouldn't hold your breath for EA to ever fix it, it's been nearly 3 years now.