Thanks to an experienced Mac developer, I got my issue resolved. I was creating a new runLoopsSource every time the method was called.
Now I've created instance variables for the tapEvent and runLoop. Only one line was needed to stop the eventTap. Modified method below:
- (void)watchEventTap
{
@autoreleasepool
{
if ( [[NSUserDefaults standardUserDefaults] isEnabledNumLockDV] == YES ) // User default toggled ON
{
_runLoopSource = NULL;
_eventTap = CGEventTapCreate(kCGHIDEventTap, kCGHeadInsertEventTap, kCGEventTapOptionDefault, CGEventMaskBit(kCGEventKeyUp) | CGEventMaskBit(kCGEventKeyDown) | CGEventMaskBit(NX_SYSDEFINED), myCGEventCallback, NULL);
_runLoopSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, _eventTap, 0);
if (!_eventTap)
{
NSLog(@"Couldn't create event tap!");
exit(1);
}
NSLog(@"Enabled. Convert taps.");
CFRunLoopAddSource(CFRunLoopGetCurrent(), _runLoopSource, kCFRunLoopCommonModes);
CGEventTapEnable(_eventTap, true);
}
else if ( [[NSUserDefaults standardUserDefaults] isEnabledNumLockDV] == NO ) // User default toggled OFF
{
NSLog(@"Disabled. Stop converting taps.");
CGEventTapEnable(_eventTap, false);
}
}
}