Obj-C Cocoa Notification NSApplicationDidResignActiveNotification

Question

I've a class called AppController.h/m I want to make something when the NSNotificationDidResignActiveNotification is sent. So i wrote this code in AppController.m:

-(void) initialize(){
    [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(applicationDidResignActive:)
                                                     name:NSApplicationDidResignActiveNotification
                                                   object:nil ];
}

and then

-(void) applicationDidResignActive (NSNotification*) note{
    NSBeep();
}

The problem is that the method isn't executed and i get this in the Console:

+[AppController applicationDidResignActive:]: unrecognized selector sent to class 0x61c4

I can't get where the problem is: could you help me?
Thank you!

Equestrian

The Amazing Captain Pedanto says "technically, you don't have a class called AppController.h/m, you have a class called AppController with a header file AppController.h and an implementation file AppController.m. Hrumph." – Designed

Answer 1

initialize is a class method, not an instance method. I don't know this for sure, but it seems that when using a selector in a class method, it also assumes that selector will be a class method (for good reason). AppController has an instance method called applicationDidResignActive, but not a class method named as such.

Instead of registering for notifications in +initialize, override -init and register there.

- (void)init
{
    [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(applicationDidResignActive:)
                                                     name:NSApplicationDidResignActiveNotification
                                                   object:nil ];
}

Okelley

thank you very much! It worked! So the problem was that the notification was sent to class and to istance, isnt'it? – Equestrian

Exactly. That plus sign in the error message was the giveaway. – Okelley