Send NSNotification from AppDelegate

Question

I want to send an NSNotification from this method (when the UIButton is clicked) in my AppDelegate.m:

- (void)alertView:(UIAlertView *)alertView 
        clickedButtonAtIndex:(NSInteger)buttonIndex{

if (buttonIndex == 0){
    //cancel clicked ...do your action
    // HERE
}
}

..and receive it in one of my UIViewControllers. How can I do that?

EDIT WITH MORE INFO: I am making an alarm app, and when the user presses the UIButton, I want to stop the alarm. I figured that NSNotifications is the only way to get information from my AppDelegate.m file to a ViewController.m file?

Answer 1

You should to register your receiver object to accept some messages sent from Notification Center.

Suppose you have Obj A which controls your alarm, and value "stopAlarm" is the message which can stop alarm. You should create an observer for a "stopAlarm" message.

You can do, with:

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(controller:)
                                             name:@"stopAlarm"
                                           object:nil];

Now, you should create a method controller that manages this messages:

 - (void)controller:(NSNotification *) notification {

     if ([[notification name] isEqualToString:@"stopAlarm"]){

         //Perform stop alarm with A object
     }
  }

Finally, you can send the message "stopAlarm" when you want in the code with:

[[NSNotificationCenter defaultCenter]
     postNotificationName:@"stopAlarm"
     object:nil];

I Hope this may help.

EDIT:

When your UIViewController are unloaded or when app terminate, you should call:

    [[NSNotificationCenter defaultCenter] removeObserver:self];

for stop observing. That's all.

Thanks to Hot licks for correction.