What's the difference between the back button on UINavigationController and PopTopViewController?

Question

I have a UINavigationController hierarchy, VC1 --> VC2.

VC1 has a table view that I need to reload when VC2 is done with its work, so VC1 has this code:

-(void)viewWillAppear:(BOOL)animated
{
    [[self tableView] reloadData];
}

VC2 is essentially working with the server to create a new table row in VC1. When the done button in VC2 is pressed, I call [navController popViewControllerAnimated:YES]. So here's what happens from the user's perspective:

1. Visit VC2, use it to create a new row for the table in VC1. Press done.

2. The hierarchy successfully navigates back to VC1, but the tableview does not reload and display the new row.

3. However, if I then nav forward to VC2, and immediately hit the navController back button, the table does reload and show the new row.

So why does [tableview reload] work on 3 but not 2? Thanks so much.

==

More code in response to answer mentioned below:

In App delegate:

    CWLandingVC *lvc = [[CWLandingVC alloc] init];
    UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:lvc];
    [[self window] setRootViewController:navController];

In VC0:

-(void)toSessionMgmtViewController
{
    TSessionMgmtViewController *tsmvc = [[TSessionMgmtViewController alloc] init];
    [[self navigationController] pushViewController:tsmvc animated:YES];
}

In VC1:

- (IBAction)toCreateSessionView:(id)sender
{
    TCreateSession *cs = [[TCreateSession alloc] init];
    [[self navigationController] pushViewController:cs animated:YES];
}

-(void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [[self tableView] reloadData];
}

In VC2: Finishes working with server...

    UINavigationController *navControler = [self navigationController];
    [navControler popViewControllerAnimated:YES];

Also, when VC2 is done working with the server, it updates a data store of TSessions called SessionListStore:

 - (TSession *)addSession:(NSString *)code withName:(NSString *) name qs:(int)qs
 {
     TSession *s = [[TSession alloc] initWithName:name code:code numberQuestions:qs];
     [_sessions setObject:s forKey:code];
     return s;
 }

where sessions is a NSNutatbleDictionary in SessionListStore.

Thanks so much in advance.

Answer 1

EDIT: The solution was to trigger the reloadData call from the completion block of Server call.

Please check this answer,

Popping ViewController doesn't call viewWillAppear when going back

Have you added navigation controller to your view controller or view controllers to your navigation controller?

Also, you can set the desired view controller as the delegate of your navigation controller and implement this method.

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated