Unfortunately iPhones just don't have a ton of computation power, but I've been given some suggestions and hopefully will have a good perf boost coming out soon!

As for that detection, this model is using Tiny YOLO, it's a simpler ML model made to run on more constrained hardware (end user devices) and therefore does not perform as well as the full YOLO or SSD. The other issue is that usually these models take context heavily into account, a fun experiment is to raise anything (ex. wallet) up to your ear and it'll interpret it as a cell phone. I've read an interesting paper recently that forces models to focus more on the object itself than the context to classify things.