Cocoa: saveAction called 2 times with notification

Question

I have a custom class for NSButton called MyButton where I post a notification for a quicksave MyButton.m:

-(void)mouseDown:(id)sender{
    [super mouseDown:sender];
    [super mouseUp:sender];
    [[NSNotificationCenter defaultCenter] postNotificationName:@"quickSave" object:nil userInfo:nil];
}

in AppDelegate I get the notification for the quick save: AppDelegate.m:

- (IBAction)saveAction:(id)sender{
    NSLog(@"Saving...");
    NSError *error = nil;
    if (![[self managedObjectContext] commitEditing]) {
        NSLog(@"%@:%@ unable to commit editing before saving", [self class], NSStringFromSelector(_cmd));
    }
    if (![[self managedObjectContext] save:&error]) {
        [[NSApplication sharedApplication] presentError:error];
    }
}
-(void)awakeFromNib{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(saveAction:) name:@"quickSave" object:nil];
}

Via the NSLog "Saving..." I see that the saveAction is called 2 times. Why?

P.S: the notification calls 2 times every function I insert in the selector: field, so maybe it has to do with the -(void)awakeFromNib{...} because I see that it's called twice (there are two different self inside the awakeFromNib).

UPDATE: I've "solved" the problem binding in Interface Builder the Application as an AppDelegate delegate and then adding the [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(saveAction:) name:@"quickSave" object:nil]; inside the -(void)applicationDidFinishLaunching:(NSNotification *)aNotification{...}. I don't know if it's a real solution and obviously it is not an answer to my question (why awakeFromNib is called 2 times), but it might be useful to someone. Does anyone have a clue?

UPDATE2: the right managedobjectcontext is the one called in awakeFromNib the second time, the first one (identical in awakeFromNib and applicationDidFinishLaunching) is wrong. My app is a statusbar app, the first awakeFromNib is called when i start the app and the second one when a preference window is opened.

Answer 1

The log message indicates that two different instances of AppDelegate receive a single notification. Probably you instantiated AppDelegate twice. Ensure you are not manually doing [[AppDelegate alloc] init] or something, and not putting more than one AppDelegate object in NIB.