kIOHIDPrimaryUsageKey
A key that specifies the primary usage type of the device.
Declaration
#define kIOHIDPrimaryUsageKeyDiscussion
The value of this key is the number for a HID usage type.
kIOHIDPrimaryUsageKey and kIOHIDPrimaryUsagePageKey are not always rich enough to describe a device’s capabilities. Take, for example, a device that describes both a keyboard and a mouse in the same descriptor. To support this more complicated scenario, use the following keys instead:
To match on only one criterion, add kIOHIDDeviceUsageKey and kIOHIDDeviceUsagePageKey to the matching dictionary. To match on multiple criteria, add kIOHIDDeviceUsagePairsKey to the matching dictionary.