- (void) startEventTap {

    NSLog(@"starting");
    //eventTap is an ivar on this class of type CFMachPortRef
    eventTap = CGEventTapCreate(kCGSessionEventTap, kCGHeadInsertEventTap, kCGEventTapOptionListenOnly, kCGEventMaskForAllEvents, myCGEventCallback, NULL);
    CGEventTapEnable(eventTap, true);
}

CGEventRef myCGEventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef event, void *refcon) {
    NSLog(@"tap");

    return NULL;

}