当我不知道会有多少节时，如何重新加载UITableView的数据？

Question

I'm a bit confused on how I can reload the cells in a UITableView after it's data has been changed. In particular, the confusion I'm having is that the new data could have more or less sections than what is currently on display. I know there's the reloadSections:withRowAnimation: method, but that requires a 1:1 replacement, where I may or may not have that.

I just want to tell the UITableView to scrap everything and reload as if for the first time. I'd appreciate someone shedding some light on this.

Thanks in advance!

UPDATE

Here's the code I'm using which I've found the issue to be the cells not dequeueing after reloadData is called...

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"];

    NSLog(@"%@", cell);

    if (cell == nil) {
        NSLog(@"%d; %d", indexPath.section, vehicle.inventoryCategoriesCount);

        if (indexPath.section < vehicle.inventoryCategoriesCount) {
            NSLog(@"Grouped cell");

            cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:@"Cell"] autorelease];

            NSString *model = [[[vehicle.inventory filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"category == %@", [vehicle.inventoryCategories objectAtIndex:indexPath.section]]] valueForKeyPath:@"@distinctUnionOfObjects.model"] objectAtIndex:indexPath.row];

            cell.textLabel.text = model;
            cell.detailTextLabel.text = [NSString stringWithFormat:@"%d", [[vehicle.inventory filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"model == %@", model]] count]];
            cell.selectionStyle = UITableViewCellSelectionStyleNone;
        } else {
            NSLog(@"Remove cell");

            cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"Cell"] autorelease];

            cell.textLabel.text = @"Remove an Item";
            cell.textLabel.textColor = [UIColor redColor];
            cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
        }
    }

    NSLog(@"Adding a cell");

    return cell;
}

Answer 1

You can call reloadData on the table view.

[myTableView reloadData];

The documentation is here: http://developer.apple.com/library/ios/#documentation/uikit/reference/UITableView_Class/Reference/Reference.html

Answer 2

If you are using core data and the fetched results controller, it's very straightforward. In fact, I believe you can see this if you build a sample core data project with a table view in it.

Two different methods come to mind: controller didChangeSection is probably what you're looking for. The first is part of the fetchedresultscontroller delegate protocol. The second is part of the tableviewdatasource protocol.

- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
       atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {

     switch(type) {
        case NSFetchedResultsChangeInsert:
        [self.noteTableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
        break;

    case NSFetchedResultsChangeDelete:
        [self.noteTableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
        break;
}

}

the other is:

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return [[fetchedResultsController sections] count];

}