Can't update a tableview automatically

Question

I have a view controller with many views and a tableview.

The tableview's cells are customized, so there is another class for setting up the cells. In each cell there is a button. The image of this button changes depending on the cell's content (this content gets read from a DB).

Basically, when the user presses the button, it changes itself to another image, a new status is written to the DB but the tableview does not update itself automatically.

The method for the button is in the custom cell class, so I've tried to instantiate my view controller (the one with the tableview) and execute a method for updating some labels in the views and the tableview:

ViewControllerWithTable *vc = [[ViewControllerWithTable alloc] init];
[vc updateEverything];

But this doesn't work. The same "updateEverything" method, called from the same "ViewControllerWithTable" (adding a reload button) works perfectly. Adding the "[tableView reloadData]" in the viewWillAppear method won't work because all the action is done in the same view.

What am I missing?

EDIT: adding some code to be more clear.

This is the method I use to update the tableview. It's inside the ViewController with the embedded tableview and it works when triggered by a button in one of the views:

- (void) updateEverything {
    // lots of DB writing and reading, plus label text changing inside all the views
    [tableView reloadData];

}

This is the IBAction for the button press and it's in the custom cell class:

-(void) btnPresaPressed:(UIButton *)sender {
    AppDelegate *deleg = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    deleg.did = sender.tag;
    NSString *s1 = NSLocalizedString(@"ALERT_TITLE", nil);
    NSString *s2 = NSLocalizedString(@"ALERT_BODY", nil);
    NSString *s3 = NSLocalizedString(@"YES", nil);
    NSString *s4 = NSLocalizedString(@"NO", nil);
    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:s1
                                                        message:s2
                                                       delegate:self
                                              cancelButtonTitle:s4
                                              otherButtonTitles:s3, nil];
    [alertView setTag:1];
    [alertView show];

}

This method shows an alert view that calls another method, always in the custom cell class:

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex {
    AppDelegate *deleg = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    DbOperations *db = [[DbOperations alloc] init];
    NSString *alrtTitle = [alertView buttonTitleAtIndex:buttonIndex];
    NSString *s3 = NSLocalizedString(@"YES", nil);
    NSString *s4 = NSLocalizedString(@"NO", nil);
    switch (alertView.tag) {
        case 1:
            //
            break;
        case 2:
            if ([alrtTitle isEqualToString:s3]) {
                // DB writing and reading
                ViewControllerWithTable *vc = [[ViewControllerWithTable alloc] init];
                [vc updateEverything];
            } else if ([alrtTitle isEqualToString:s4]){
                //

            }
            break;
        case 3:
            if ([alrtTitle isEqualToString:s3]) {
                //
            }
            break;
        default:
            break;
    }

}

In this case, the updateEverything method don't work.

Answer 1

EDIT after you added more code:

In the following lines:

        if ([alrtTitle isEqualToString:s3]) {
            // DB writing and reading
            ViewControllerWithTable *vc = [[ViewControllerWithTable alloc] init];
            [vc updateEverything];

you are instantiating a new view controller altogether that has nothing to do with your original view controller that displayed the table view. So, you are sending the update message to the wrong object.

What you need is a mechanism for your cell to know which is the right controller to send the message to.

One easy solution would be using NSNotificationCenter:

1. the view controller register itself for a certain kind of notification:

   [[NSNotificationCenter defaultCenter]
   addObserver:self
   selector:@selector(updateEverything:)
   name:kCellSentUpdateMessageNotification
   object:nil];
   

2. your cell sends the notification, instead of calling the message directly:

   [[NSNotificationCenter defaultCenter] postNotificationName:kCellSentUpdateMessageNotification object:nil];
   

OLD Answer:

You should call

  [self.tableView reloadData]

from your updateEverything method implementation. This will reload the table data, effectively updating its rows appearance. The updateEverything method shall be called when tapping on the button in a row for this to work, obviously.

If that does not work, please provide more code.

Answer 2

This is your problem:

The method for the button is in the custom cell class, so I've tried to instantiate my view controller (the one with the tableview) and execute a method for updating some labels in the views and the tableview:

You created an entirely new view controller that has no knowledge of your tableview. The best thing to do is to create a property in your cell subclass and set it to your view controller when you set the cell. Then you can call your updateEverything method on that property.

Answer 3

Have you try to put

[[self tableView] reloadData];

I remember I had an issue like that, and this line on top solve my problem.