I've used this Innova OBD Code Reader 1000

https://www.oreillyauto.com/detail/c/innova/tools---equipment/diagnostic-tools/code-readers-scanners/5609f7011617/innova-obd-code-reader/inn0/1000/v/a/129830/automotive-truck-2015-gmc-canyon?q=code+readers%2Fscanners&pos=5

Helped me out and saved me a bunch of cash.

Doesn't specifically say if it works with Apple, but does say "any smartphone".