Question

I am having trouble getting a viewController to receive notifications from NSNotificationCenter. Where am I going wrong?

In my viewController, I have defined :

- (id)init {

    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(receiveEvent:)
                                                 name:UIApplicationWillResignActiveNotification
                                               object:nil];


    return self;
}


- (void)receiveEvent:(NSNotification *)notification {
    counter = counter + 1;
    NSString *string = [NSString stringWithFormat:@"%d", counter];  
    vocabword.text = string;
}

But the text is not updating 🙁

Answer 1

Is your init method being called? (and, why aren’t you calling [super init] in there?)

Depending on how you construct your viewController, the init method itself may not be called. Rather, anther initializer might be used, such as initWithCoder: if being loaded from a xib.

Typically I’ll register for notifications in viewDidLoad and unregister in viewDidUnload. Is there a reason you’d need to receive the notification if your view were unloaded for some reason (e.g. too much memory pressure?)