NSNotificationCenter doesn't work in popup view(ios objC)

Question

I'm working on a iPad project(xcode 7.21+iOS9) and NSNotificationCenter doesn't work.

When user open my app, the tab bar controller will appear.

- (void)viewWillAppear:(BOOL)animated {
    if (false == [[MyClass sharedData] getLoginStatus])
    {
        LoginViewController *loginViewController = [[UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil] instantiateViewControllerWithIdentifier:@"myCustomPopoverLoginVC"];
            loginViewController.modalPresentationStyle = UIModalPresentationFormSheet;
            [self presentViewController:loginViewController animated:YES completion:^{

        }];
...
    }
}

- (void)viewDidLoad
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(notificationLogin:) name:@"afterLogin" object:nil];
    [super viewDidLoad];
...
}

-(void)notificationLogin:(NSNotification *)notification{
    NSLog(@"OhOhOh");
}

In my loginView,

-(IBAction)login:(id)sender{
    ...
    [[NSNotificationCenter defaultCenter] postNotificationName:@"afterLogin" object:nil];
    ...
}

Answer 1

First of all:

- (void)viewWillAppear:(BOOL)animated {
    if (false == [[MyClass sharedData] getLoginStatus])
    {
        LoginViewController *loginViewController = [[UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil] instantiateViewControllerWithIdentifier:@"myCustomPopoverLoginVC"];
            loginViewController.modalPresentationStyle = UIModalPresentationFormSheet;
            [self presentViewController:loginViewController animated:YES completion:^{

        }];
...
    }
}

- (void)viewDidLoad
{
    // Add log here to check when its called
    -------> NSLog("Add Observer");
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(notificationLogin:) name:@"afterLogin" object:nil];
    [super viewDidLoad];
...
}

-(void)notificationLogin:(NSNotification *)notification{
    NSLog(@"OhOhOh");
}

then add another log here :

-(IBAction)login:(id)sender{
    ...
    -------> NSLog("Post notification");
    [[NSNotificationCenter defaultCenter] postNotificationName:@"afterLogin" object:nil];
    ...
}

So you can check what called first. Then refer @Sandeep Kumar comment :)) NSNotificationCenter doesn't work in popup view(ios objC)