I would advise you to try MelonDS. I don't have a Mac but it works pretty well and it's really easy to set up. You can even easily add cheats.
Many people use DesMuMe, which is fine too, but I personally had some issues with configuring cheats, so that's why I generally advise MelonDS.
When I had a Mac I used OpenEmu, so I would give a look at that as well. Another option is Retroarch, but it can be hard to set it up.