I'm trying to learn how to use Darwin Notifications, and I'm having trouble getting my callback function to trigger. I've been writing a command line tool just to learn how to get Darwin notifications working, but eventually will use them in an iPhone app. I have sample code below; can anyone with Darwin Notifications experience point out what am I doing wrong? //callback static void myCallback(CFNotificationCenterRef center, void *observer, CFStringRef name, const void *object, CFDictionaryRef userInfo) { NSLog(@"In callback function"); } int main(int argc, const char * argv[]) { // Add Observer CFNotificationCenterAddObserver( CFNotificationCenterGetDarwinNotifyCenter(), //center NULL, //observer myCallback, //callback CFSTR("sanity_check"), //event name NULL, //object CFNotificationSuspensionBehaviorDeliverImmediately ); // Post notification 1 CFNotificationCenterPostNotification( CFNotificationCenterGetDarwinNotifyCenter(), // center CFSTR("sanity_check"), // event name NULL, //object NULL, //userinfo dictionary true); // Post notification 2 notify_post("sanity_check"); return 0; }