Se eu tenho um UITableView que tem 4 linhas nele, o método cellForRowAtIndexPath não deve ser chamado 4 vezes quando eu navego para essa view? Eu estou achando que está sendo chamado várias vezes, e. se houver 4 linhas, ele será chamado 8 vezes quando eu detalhar a visualização do UITable e, em seguida, 12 vezes quando eu navegar de volta para o mesmo UITableView.

Eu estou apenas entendendo mal como esse método funciona? Eu pensei que deveria ser chamado uma vez para cada linha que é exibida (não há rolagem envolvida como o conteúdo da visão de tabela cabe facilmente na tela do meu iPad).

Eu provavelmente deveria notar que o UITableView está contido no MasterViewController de um UISplitViewController em um iPad.

EDIT: O problema real que estou recebendo é inconsistência na maneira que o código a seguir está sendo aplicado:

<code>if (selectedNavItem.folder.isAssignedToUser != [NSNumber numberWithInt:1]) 
        {
            NSLog(@"%@", cell.textLabel.text);
            cell.selectionStyle = UITableViewCellSelectionStyleNone;
            cell.userInteractionEnabled = NO;
            cell.textLabel.enabled = NO;
            cell.detailTextLabel.text = @"Access not granted";
            cell.detailTextLabel.enabled = NO;
        }
</code>

Quando eu primeiro "detalho" para um determinado nível da minha pilha de navegação, as coisas funcionam como deveriam. Mas, mais tarde, se eu navegar de volta para cima ou para baixo, descubro que várias linhas são tratadas incorretamente, ou seja, elas acabam desativadas quando devem ser ativadas. Isso me levou a colocar um ponto de interrupção e algum código de registro para tentar descobrir o que estava acontecendo. Descobri que o código acima estava sendo chamado mais vezes do que havia linhas - e o valor cell.textLabel.text que eu estava registrando não fazia sentido - um valor para a mesma linha estava sendo registrado várias vezes - e outras linhas não eram sendo logado em tudo.

EDIT: fornecendo alguns códigos conforme solicitado:

<code>    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"FolderCell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    [self configureCell:cell atIndexPath:indexPath];
    return cell;
}


- (NSFetchedResultsController *)fetchedResultsController
{
    if (__fetchedResultsController != nil) {
        return __fetchedResultsController;
    }

    // Set up the fetched results controller.
    // Create the fetch request for the entity.
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    // Edit the entity name as appropriate.
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"NavItem" inManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:entity];

    // Set the batch size to a suitable number.
    [fetchRequest setFetchBatchSize:20];

    // Edit the sort keys as appropriate.
    NSSortDescriptor *sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:@"sortOrder" ascending:YES];
    NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)];
    NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor1, sortDescriptor2, nil];

    [fetchRequest setSortDescriptors:sortDescriptors];

    // Edit the section name key path and cache name if appropriate.
    // nil for section name key path means "no sections".
    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.
        managedObjectContext sectionNameKeyPath:nil cacheName:@"Master"];
    aFetchedResultsController.delegate = self;
    self.fetchedResultsController = aFetchedResultsController;

    NSError *error = nil;
    if (![self.fetchedResultsController performFetch:&error]) {
        /*
         Replace this implementation with code to handle the error appropriately.

         abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. 
         */
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    return __fetchedResultsController;
}   

- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{
    NSManagedObject *managedObject = [self.fetchedResultsController objectAtIndexPath:indexPath];
    NavItem *selectedNavItem = (NavItem *)managedObject;
    cell.textLabel.text = [[managedObject valueForKey:@"name"] description];
    cell.detailTextLabel.text = @"";

    if (selectedNavItem.folder != nil) {
        cell.imageView.image = [UIImage imageNamed:@"Folder.png"];


        //NSLog(@"%@", selectedNavItem.folder.isAssignedToUser);

        if (selectedNavItem.folder.isAssignedToUser != [NSNumber numberWithInt:1]) 
        {
            NSLog(@"%@", cell.textLabel.text);
            cell.selectionStyle = UITableViewCellSelectionStyleNone;
            cell.userInteractionEnabled = NO;
            cell.textLabel.enabled = NO;
            cell.detailTextLabel.text = @"Access not granted";
            cell.detailTextLabel.enabled = NO;
        }
    }
    else if (selectedNavItem.document != nil) {
        cell.detailTextLabel.text  = [[selectedNavItem.document valueForKey:@"itemDescription"] description];

        if ([[selectedNavItem.document.fileName pathExtension] isEqualToString:@"pdf"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"pdf.png"];
        }
        else if ([[selectedNavItem.document.fileName pathExtension] isEqualToString:@"doc"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"docx"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"Word-32x32.png"];
        }
        else if ([[selectedNavItem.document.fileName pathExtension] isEqualToString:@"xls"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"xlsx"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"Excel-32x32.png"];
        }
        else if ([[selectedNavItem.document.fileName pathExtension] isEqualToString:@"ppt"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"pps"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"Powerpoint-32x32.png"];
        }
        else if ([[selectedNavItem.document.fileName pathExtension] isEqualToString:@"mp3"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"wav"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"65-note.png"];
        }
        else if ([[selectedNavItem.document.fileName pathExtension] isEqualToString:@"mp4"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"mov"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"46-movie-2.png"];
        }
        else if ([[selectedNavItem.document.fileName pathExtension] isEqualToString:@"ibooks"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"ibooks-icon.png"];
        }
        else if ([[selectedNavItem.document.fileName pathExtension] isEqualToString:@"png"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"bmp"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"jpg"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"jpeg"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"tif"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"tiff"] || [[selectedNavItem.document.fileName pathExtension] isEqualToString:@"gif"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"41-picture-frame.png"];
        }
        else 
        {
            cell.imageView.image = [UIImage imageNamed:@"179-notepad.png"];
        }


    }
    else if (selectedNavItem.attachment != nil) {
        cell.detailTextLabel.text  = [[selectedNavItem.attachment valueForKey:@"itemDescription"] description];

        if ([[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"pdf"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"pdf.png"];
        }
        else if ([[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"doc"] || [[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"docx"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"Word-32x32.png"];
        }
        else if ([[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"xls"] || [[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"xlsx"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"Excel-32x32.png"];
        }
        else if ([[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"ppt"] || [[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"pps"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"Powerpoint-32x32.png"];
        }
        else if ([[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"mp3"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"65-note.png"];
        }
        else if ([[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"mp4"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"46-movie-2.png"];
        }
        else if ([[selectedNavItem.document.fileName pathExtension] isEqualToString:@"ibooks"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"ibooks-icon.png"];
        }
        else if ([[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"png"] || [[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"bmp"] || [[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"jpg"] || [[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"jpeg"] || [[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"tif"] || [[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"tiff"] || [[selectedNavItem.attachment.fileName pathExtension] isEqualToString:@"gif"]) 
        {
            cell.imageView.image = [UIImage imageNamed:@"41-picture-frame.png"];
        }
        else 
        {
            cell.imageView.image = [UIImage imageNamed:@"179-notepad.png"];
        }
    }

}
</code>