Ios – Send and receive messages through NSNotificationCenter in Objective-C


I am attempting to send and receive messages through NSNotificationCenter in Objective-C. However, I haven't been able to find any examples on how to do this. How do you send and receive messages through NSNotificationCenter?

Best Solution

@implementation TestClass

- (void) dealloc
    // If you don't remove yourself as an observer, the Notification Center
    // will continue to try and send notification objects to the deallocated
    // object.
    [[NSNotificationCenter defaultCenter] removeObserver:self];
    [super dealloc];

- (id) init
    self = [super init];
    if (!self) return nil;

    // Add this instance of TestClass as an observer of the TestNotification.
    // We tell the notification center to inform us of "TestNotification"
    // notifications using the receiveTestNotification: selector. By
    // specifying object:nil, we tell the notification center that we are not
    // interested in who posted the notification. If you provided an actual
    // object rather than nil, the notification center will only notify you
    // when the notification was posted by that particular object.

    [[NSNotificationCenter defaultCenter] addObserver:self

    return self;

- (void) receiveTestNotification:(NSNotification *) notification
    // [notification name] should always be @"TestNotification"
    // unless you use this method for observation of other notifications
    // as well.

    if ([[notification name] isEqualToString:@"TestNotification"])
        NSLog (@"Successfully received the test notification!");


... somewhere else in another class ...

- (void) someMethod

    // All instances of TestClass will be notified
    [[NSNotificationCenter defaultCenter]