Getting NSNotification to Work?

Question

I'm currently trying to get NSNotification to work but I'm having some trouble.

I have two (2) ViewControllers: A. MainViewController & B. LoginViewController.

In my MainViewController I have a logout button that will send a url to my LoginViewController to load it (without showing my loginView). However, it's not working.

In my MainViewController this is what I have:

- (IBAction)logout:(id)sender {

NSURL *logoutURL = [NSURL URLWithString:@"https://myurl.com/logout"];

[[NSNotificationCenter defaultCenter] postNotificationName:@"logoutInitiated" object:logoutURL];


}

This is what I have in my LoginViewController:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    WebView.delegate = self;
    WebView.scalesPageToFit = YES;
    WebView.multipleTouchEnabled = YES;
    loadCount = 0;

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

}

- (IBAction)submitLogout:(NSNotification*)notification {


   [WebView stopLoading];

    NSURL * signOutUrl = (NSURL*)[notification object];
    [self loadURL:nil withURL:signOutUrl];
}

My problem is that when I press the logoutButton nothing happens. (Using NSLogs, I see that it never triggers the next step) Thank you!!!!

Answer 1

This is because your method name you are passing in selector is wrong. You need to add colon : at submitLogout: suffix Use

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

in place of

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

Hope it helps you.

Answer 2

When you add self as an observer, you use the selector "submitLogout" without a semicolon! But your method has an argument, so the correct selector would be @selector(submitLogout:).

Answer 3

Note the SEMICOLON

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(**submitLogout:**) name:@"logoutInitiated" object:nil];    

- (IBAction)logout:(id)sender 
{
        NSURL *logoutURL = [NSURL URLWithString:@"https://myurl.com/logout"];    
        [[NSNotificationCenter defaultCenter] postNotificationName:@"logoutInitiated" object:nil       userInfo:[NSDictionary dictionaryWithObjectsAndKeys:logoutURL,@"RECEIVED_URL", nil]];
}

- (IBAction)submitLogout:(NSNotification*)notification 
{       
    [WebView stopLoading];
     NSURL * signOutUrl = (NSURL*)[notification objectForKey:@"RECEIVED_URL"];
    [self loadURL:nil withURL:signOutUrl];
}