iphone - Core Data: UITableView with multiple NSFetchedResultControllers

Question

What I want to do is pretty simple. In my UITableViewController, I want to load data from multiple NSFetchedResultControllers (I have multiple entities in my data model) and put data from each one into a different section in the table view. So for example, all the fetched items from the first NSFetchedResultController would go in section 0 in the UITableView, the fetched items from the other one goes into section 1, etc.

The Core Data template project doesn't demonstrate how to do this. Everything (mainly the index paths) is coded without taking sections into account (there are no sections in the default template) and everything is taken from a single NSFetchedResultController. Are there any example projects or documentation that demonstrates doing this?

Thanks

Answer 1

Assume for a moment the following in your header (code below will be slightly sloppy, my apologies):

NSFetchedResultsController *fetchedResultsController1; // first section data
NSFetchedResultsController *fetchedResultsController2; // second section data

Let the table know you want to have 2 sections:

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 2; // you wanted 2 sections
}

Give it the section titles:

- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView {
    return [NSArray arrayWithObjects:@"First section title", @"Second section title", nil];
}

Let the table know how many rows there are per sections:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    if (section == 0) {
        return [[fetchedResultsController1 fetchedObjects] count];
    } else if (section == 1) {
        return [[fetchedResultsController2 fetchedObjects] count];
    }

    return 0;
}

Build the cell:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    ... // table cell dequeue or creation, boilerplate stuff

    // customize the cell
    if (indexPath.section == 0) {
        // get the managed object from fetchedResultsController1
        // customize the cell based on the data
    } else if (indexPath.section == 1) {
        // get the managed object from fetchedResultsController2
        // customize the cell based on the data
    }

    return cell;
}