Navigating back to UIViewController from TableViewController using NSNotifications

Question

I have an exception like this:

Thread 1: EXC_Breakpoint (code = EXC_I386_BPT,subcode=0x0)

In my story board i have 3 controllers. Navigation controller, UIViewController and then a tableviewcontroller. When the app first launches UIViewController is shown. I add some stuff to the Core Data DB. Then on this controller itself i have a "Check Records" bar button. I click that and move to the 3rd controller the tableviewcontroller. Here i can see the records that i added on that day. I click the one i just added and traverse back to the UIviewcontroller screen using NSNotifications like this:

//This code is in tableviewcontroller.didSelectRowAtIndexPath

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
ITMAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
    appDelegate.salesOrderObject = [self.salesOrdersArray objectAtIndex:indexPath.row];

    NSNotification *notification =[NSNotification notificationWithName:@"reloadRequest"
                                                                object:self];
    [[NSNotificationCenter defaultCenter] postNotification : notification];

    [self.navigationController popViewControllerAnimated:YES];
}

In my ViewController viewDidLoad i write this code to listen to the notification.

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


-(void)newReloadData
{
self.salesOrder =  self.appDelegate.salesOrderObject; //self.reloadedSOObject; //appDelegate.salesOrderObject;

if(self.salesOrder !=nil)
{
//I add UItextviews,textfields,buttons etc here to a scrollview.
ITMCustomView *cView = [[ITMCustomView alloc] initWithFrame:CGRectMake(187, 660, 400, 400)
                                                     andOrderedItem:@"New"
                                                             andTag:self.tagNumber
                                                      withFoldArray:self.foldTypeArray
                                                      withRollArray:self.rollTypeArray];

        cView.tag =self.tagNumber;
        NSLog(@"Assigned tag is %d",cView.tag);

        cView.delegate = self;

        //[self.scrollView addSubview:customView];

        //self.scrollView.contentSize = CGRectMake(187, 660, 400, 400).size;


        CGPoint scrollPoint = CGPointMake(0.0, (cView.frame.origin.y/500)*400);
        [self.scrollView setContentOffset:scrollPoint animated:YES];

        [self.scrollView addSubview:cView];

        CGFloat scrollViewHeight = 0.0f;
        for (UIView *view in self.scrollView.subviews)
        {
            scrollViewHeight += view.frame.size.height;
        }

        CGSize newSize = CGSizeMake(320,scrollViewHeight);
        //CGRect newFrame = (CGRect){CGPointZero,newSize};
        [self.scrollView setContentSize:newSize];
        NSLog(@"750 the tag number is %d",self.tagNumber);
        NSLog(@"the scroll view height is %f",scrollViewHeight);
        self.currentCGRectLocation = cView.frame;
}
}

I am thinking if the exception occurs at adding something to scroll view.Or on looking some more on stack overflow it could be either because of delegate or NSnotification. I cant figure out why and where the exception occurs.Does writing this line of code give me this exception?

[self.navigationController popViewControllerAnimated:YES];

this question is extension of this question Adding Customview to UIScrollview results in stuck screen when Scrolling

I have no idea where/how its getting this exception. If you need more info please ask. Thanks...

maybe you need try to enable zombies and guard malloc maybe you can get some detail on error . or use some breakpoints to understand after what point it occurs and I would use `popViewControllerAnimated:NO` — SpaceDust__, Dec 26 '12 at 18:23
@SpaceDust. Thanks. I enabled zombies and guard malloc, but no use.I also changed the popViewControllerAnimated to NO and it didn't work. So the exception seems to be occurring at [self.navigationController popViewControllerAnimated:NO]; line.It hits this line and then it throws the above exception. Also can i pass object to AppDelegate class like that?I am storing my object in appDelegate class at didSelectRowAtIndexPath and while working with the notification i retrieve an object from the AppDelegate class. — RookieAppler, Dec 26 '12 at 18:46
one thing might be you first call `newReloadData` because you notify notification center that what class has `newReloadData` method should run it, so you need to first pop the view then call the notification, just try change the line order first call `[self.navigationController popViewControllerAnimated:YES];` then call `[[NSNotificationCenter defaultCenter] postNotification : notification];` — SpaceDust__, Dec 26 '12 at 19:07
I am glad that worked, I am looking at your code but honestly I have no idea why scroll is disabled, maybe you should ask another question or wait for someone to solve your issue. But about `NSNotifications` part I deserve my answer is checked :) — SpaceDust__, Dec 26 '12 at 19:19

score 1 · Accepted Answer · answered Dec 26 '12 at 19:17

One thing might be when you call newReloadData you notify notification center that what class has@"reloadRequest" string with newReloadData method should run it, so you need to first pop the view then call the notification

Just try change the line order first call [self.navigationController popViewControllerAnimated:YES]; then call [[NSNotificationCenter defaultCenter] postNotification : notification];

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
ITMAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
    appDelegate.salesOrderObject = [self.salesOrdersArray objectAtIndex:indexPath.row];

    NSNotification *notification =[NSNotification notificationWithName:@"reloadRequest"
                                                                object:self];
    //here first pop view
    [self.navigationController popViewControllerAnimated:YES];

    //then send notification before scopes end
    [[NSNotificationCenter defaultCenter] postNotification : notification];


}

@SpaceDust.Thanks.That Worked.NO exception!!!. I can see the viewcontroller fine, but the scroll is disenabled. Screen is stuck.I can neither move up/down — RookieAppler, Dec 26 '12 at 19:21

Navigating back to UIViewController from TableViewController using NSNotifications

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