How to implement IOServiceMatchingCallBack in Swift

Question

I would like to detect a specific USB is plugged in/removed in my application. For now, I can get the deviceName with this tutorial Working With USB Device Interfaces. But,

Answer 1

Got this working thanks! Only problem was that I wasn't using the iterator in my callback function, so that function wasn't even getting called! Seems like strange behaviour to me, but that was my problem