Provide basic troubleshooting steps you can take yourself to resolve problems with your game without having to post on the forums asking for help.
Provide helpful links regarding general gameplay, graphics and CC/Mods
Make users aware of general game bugs which affect both Mac and Windows users.
Report Mac specific issues
Basic troubleshooting steps:
The very first thing you should try when experiencing problems, especially crashing ones or the game not loading, is to move your Sims 4 folder out onto your desktop and let the game generate a new one (just like in The Sims 3). You can find the folder in Documents > Electronic Arts > The Sims 4. If your game then works ok the problem was in your user data (most causes for this are incompatible or conflicting CC/Mods). Now you have a nice, new, clean user data folder you can try adding your old data back into the game gradually, testing after each addition. For example, copy your saves from your old The Sims 4 folder into the new one. If your game once again doesn't perform properly then you know that there is a problem somewhere in your saves, one or more may be corrupted. For more information on Saves read this.
Try repairing your game. Open Origin, go to My Games, right click on The Sims 4 image and select Repair Game.
Disable Origin in Game. Open Origin, navigate to the The Sims 4 image in My Games, right click on the game and select Game Properties. Make sure Disable Origin in Game for this game is ticked.
The cheat console can be opened by holding down CTRL, Shift and C together. If this is not working for you check your keyboard configuration in System Preferences, have you changed it in the past? Have you changed something in System Preferences > Accessibility > Keyboard? Have you changed the Modifier keys? The cheat console is coded into the game, there is no reason why it shouldn't work unless the user has changed some settings or has software installed which may be conflicting with the keyboard settings. Check whether your CTRL key is faulty or broken. If all else fails, try plugging in or bluetoothing another keyboard to your Mac.
If you have Origin open but your game won't load, quit Origin then try launching the game again from the Sims 4 icon in your Applications folder.
If your game still isn't working after trying those recommendations and you would like some help, PLEASE post the following information (examples in brackets). It is unfair to expect anyone to help you if you do not take the time to post the information we need to work out what the problem may be. Please also take the time to click on threads that people link to that may help you. A lot of time and effort is spent on compiling information and most of the time your problem will already have been reported and answered, whether there is a solution or not. To find the info about your Mac click on the Apple icon, top left of your desktop then select About This Mac:
Mac model(mid-2012 15" non-Retina MacBook Pro)
Processor(2.6 GHz Intel Core i7)
Graphics(Intel HD 4000 1Gb/NVIDIA GeForce GT 650M 1Gb)
Operating System(OS X Yosemite 10.10.5)
Official EA EPs/SPs/GPs installed(Get To Work, Outdoor Retreat, Spa Day, Luxury Party Stuff, Perfect Patio Stuff, Cool Kitchen Stuff)
Do you have antivirus or clean up apps installed? If so what are they?(Sophos, AVG, MacKeeper, SimpleCleaner)
Are you running any background tasks? If so, what are they?(Time Machine, Dropbox, Memory Clean)
Do you have any CC/mods installed?
General Gameplay tips:
If you want to copy your save games into a new game installation navigate to Documents > Electronic Arts > The Sims 4 and copy your saves folder onto a USB stick. You can then place this folder into the Documents > Electronic Arts > The Sims 4 folder on your Mac, replacing any saves folder you already have in there that you do not want. Only copy over the saves folder, not the whole Sims 4 folder. You can also move over the Tray folder if you want to keep the Lots/Sims you've saved to your Library.
The best place to find game tips, such as keyboard controls and a general Q&A is Simsocity's help thread. You can find it stickied here.
If you haven't yet installed The Sims 4 in OS X, and want to know if your Mac can handle it, please read this thread.
Want to know how well the game can perform on your Mac? It's all about the graphics card. Read this thread to get an idea of how well you will be able to play.
If you want to stop your game from storing all the little thumbnail images from the Gallery you can use Automator to write a simple script to automatically delete them.
If you play on two or more Macs, and want the same save game on all of them, you can use a file sharing site and MacDropAny to sync your saves automatically