MacOS Virtual Input Devices

How can I create a virtual HID device in code? I'm trying to avoid writing a kernel extension to accomplish this, but it seems to be the only way. I need to be able to create virtual 开发者_高级运维HID devices of all types, and have an app running in the background feed them events. Is there a way to do this in user-space, or must I venture into kernel land?

The typical way of creating HID devices is to use the IOHID* classes in IOKit. You can write a userclient that passes events in and out.

I'm not sure what a "virtual" HID device is, however, I guess. If you want to create a keyboard on the screen, that sort of thing can probably be done in userspace.