I have a custom HID device that works on Windows totally fine with the default HID driver. The HID device knows how to accept string commands to control it and respond accordingly. I am trying to control it on Mac using IOKit. I am able to get the io_service_t reference to the IOHIDInterface for the device from the I/ORegistery. I use this to instantiate a class to represent the device. But when I try to establish a connection to the service, I keep getting -536870201 which corresponds to kIOReturnUnsupported. I'm not entirely sure what I am doing wrong here and I wasn't able to find anything online that could really help.

I have a custom HID USB device that I can control on Mac with IOKit via the default HID MacOS driver. I am using IOHIDManager to detect it and send reports to it. I would like to extend this capability to iPad but the full IOKit framework is not supported on iOS/iPadOS. I saw that USBDriverKit is now supported on iPads with an M1 chip or newer. But, both MacOS and Windows can operate the device with their generic HID driver. As such, having to create a whole custom driver to interact with an HID device on iOS is really overkill. Would registering it in the MFi Program and operating it with the External Accessory framework be the correct route to take here? Or is there another framework for controlling HID devices on iPad over USB that I am not aware of?