NSApplicationWillTerminateNotification not Working

My problem is that the NSApplicationWillTerminateNotification is not called when I quit my applicat开发者_运维技巧ion. What I have tried: (appDelegate.m)

- (void) applicationDidFinishLaunching:(NSNotification *)aNotification{
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillTerminate:) name:NSApplicationWillTerminateNotification object:nil];
}

- (void)applicationWillTerminate:(NSNotification *)aNotification{
NSLog(@"quit");
}

OR

- (void)applicationWillTerminate:(NSApplication *)application{
NSLog(@"Quit");
}

My application has no window, as it is a background application -> I deleted the window and the menu in interface Builder.

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Apps in the background are terminated without any notification.