NSNotificationCenter previously working in iOS 6.1 - iOS 7 issue?

Question

I have the following snippet of code in viewDidLoad which I post a notification to be received by a different ViewController, and prior to iOS 7 (and XCode 5) this has worked:

if ([PFUser currentUser] && [PFFacebookUtils isLinkedWithUser:[PFUser currentUser]]) {
        NSLog(@"Current user exists and is logged in"); //current works, so I know that this if-statement is satisfied
        [self performSegueWithIdentifier:@"GoToRatingsView" sender:self];
        [[NSNotificationCenter defaultCenter] postNotificationName:@"testSetup" object:nil]; //part in question
    }

And in the segued ViewController, I have the following:

(void)viewDidLoad
{
    [super viewDidLoad];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(testSetupFunction) name:@"testSetup" object:nil];
}

(void)testSetupFunction
{
    NSLog(@"This function executed");
}

Currently, testSetupFunction does not executed, which means the notification is not received. I am unsure whether its because I have segued to a different view and then posted the notification, or that this is something new with iOS 7, but currently the notification is no longer received.

Thanks for your help!

Have you stepped through the viewDidLoad method and made sure that the line posting the notification is actually reached? — rocky, Oct 16 '13 at 23:39
Good suggestion - I did step through the original method posted in the ViewController and the `viewDidLoad` method in the segued view controller. In both cases the line posting and listening for the notification were reached. — daspianist, Oct 17 '13 at 01:46

Kevin · Accepted Answer · 2014-01-21T03:48:58.837

3

Post the notification once the viewcontroller has time to load.

- (void)postNotificaiton
{
    [[NSNotificationCenter defaultCenter] postNotificationName:@"testSetup" object:nil];
}

if ([PFUser currentUser] && [PFFacebookUtils isLinkedWithUser:[PFUser currentUser]]) {
    [self performSegueWithIdentifier:@"GoToRatingsView" sender:self];
    [self performSelector:@selector(postNotification) withObject:nil afterDelay:0.0];
}

You could also post a notification from your segued View Controller saying that it was loaded, and in response to that notification, post your testSetup notification.

edited Jan 21 '14 at 03:48

answered Oct 17 '13 at 00:00

Kevin

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This did the trick - thanks! What was strange was that even when I put a delay of `0.0` it still worked. However, if I called posted the notification in the original manner, it would not work.. Thanks for this workaround! – daspianist Oct 17 '13 at 01:51
1

This also works for me, but not when I put a delay of 0.0. I wonder if there's an explanation to this. – tyegah123 Jan 21 '14 at 03:24
Me to, neede that delay – JSA986 Jan 21 '14 at 12:27

Anshul Jain · Answer 2 · 2013-10-17T01:48:21.350

did you try adding the observer in the init method

    - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
          [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(testSetupFunction) name:@"testSetup" object:nil];                   

        // Custom initialization
    }
    return self;
}

OR You can also try to put a log in viewDidLoad to check actually the view is loaded at that time, sometimes it takes time to load the view, view is only loaded only when it is needed.

NSNotificationCenter previously working in iOS 6.1 - iOS 7 issue?

2 Answers2