Monitor keyboard events by adding observer in RunLoop

Question

My Run Loop Observer is written as follows:

void observerCallback(CFRunLoopObserverRef observer,
    CFRunLoopActivity activity, void* info)
{
    println("%u", activity);
}
//----------------------------- 
void InstallObserver()
{
    CFRunLoopObserverRef myObserver = NULL;
    int myActivities = kCFRunLoopEntry;

    myObserver = CFRunLoopObserverCreate(NULL, myActivities, YES,
        /* repeat */ 0, &observerCallback, NULL);

    if (myObserver)
    {
        CFRunLoopAddObserver(CFRunLoopGetCurrent(), myObserver,
            kCFRunLoopCommonModes);
    }
}

Every time I press any key in my Application the observerCallback is called 4 times. The question is: How can I obtain key code inside observerCallback? Thanks.

What are you trying to do here with the run loop that you can't do by responding to the event stream? CFRunLoop happens to be triggered with these events, but the trigger is basically to process the event using the responder framework, and as such, the run loop itself isn't getting the information you are seeking. — gaige, Jul 12 '12 at 09:00
My friend gaige! How can I use "event stream" for this purpose? Is It possible to help me? thankyou. — mh taqia, Jul 12 '12 at 10:29
I want to monitor keyboard events in my process space (not system wide). It seems the InstallEventHandler (with target = GetApplicationEventTarget) not supported in cocoa apps (needs carbon run loop). if target be GetEventMonitorTarget() then "Universal access" is needed to activate (I do not want it). — mh taqia, Jul 12 '12 at 13:45
Is this an App that has no windows? The reason that I ask is that there are some approaches, but each has its own requirements and depending on what your requirements actually are will depend what solutions make sense. Do you have a window that you want to monitor events in? — gaige, Jul 13 '12 at 09:07
No, I have no window. Indeed I have written a dylib that is injected into another programms (such as TextEdit) for some purposes. the code should be executed inside dylib considering the fact that no window is accessible. — mh taqia, Jul 13 '12 at 10:12

score 0 · Accepted Answer · answered Jan 24 '14 at 04:17

Based on the comments on your question, you want a local event monitor, AKA:

+[NSEvent addLocalMonitorForEventsMatchingMask:handler:]

https://developer.apple.com/library/mac/documentation/Cocoa/Reference/ApplicationKit/Classes/NSEvent_Class/Reference/Reference.html#//apple_ref/occ/clm/NSEvent/addLocalMonitorForEventsMatchingMask:handler:

Monitor keyboard events by adding observer in RunLoop

1 Answers1