CoreData : Fetch Multiple Entities using NSFetchedResultController

Question

I can fetch one entity and display the data in a tableview with single section using NSFetchedResultsController . But how to fetch two or more entities (no relation) using NSFetchedResultsController and display the data in different section?

I noticed that using core data, I can get number of section and number of row using NSFetchedResultsController . I set one entity in NSFetchedResultsController and it handles tableView very well including add and delete row.

 func getFetchedResultController() - > NSFetchedResultsController { fetchedResultController = NSFetchedResultsController(fetchRequest: fetchRequest(), managedObjectContext: managedObjectContext!, sectionNameKeyPath: nil, cacheName: nil) fetchedResultController.delegate = self fetchedResultController.performFetch(nil) return fetchedResultController } func fetchRequest() - > NSFetchRequest { let fetchRequest = NSFetchRequest(entityName: "Fruits") let sortDescriptor = NSSortDescriptor(key: "desc", ascending: true) fetchRequest.sortDescriptors = [sortDescriptor] return fetchRequest } override func numberOfSectionsInTableView(tableView: UITableView) - > Int { let section = fetchedResultController.sections ? .count return section! } override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) - > Int { if let s = fetchedResultController.sections as ? [NSFetchedResultsSectionInfo] { return s[section].numberOfObjects } return 0 } override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) - > UITableViewCell { var cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as UITableViewCell let fruit = fetchedResultController.objectAtIndexPath(indexPath) as Fruits cell.textLabel.text = fruit.desc return cell } 

But section always zero because it only uses one entity. Let say I want to show 2 entities/tables Fruits and Drinks (no relation), where should I put these entities in my code above? Can NSFetchedResultsController handles these entities in different section in tableView ?

Answer 1

Use two fetchedResultsControllers , say fruitFRC and drinksFRC , and then map the indexPath reported by those FRCs to the indexPath used by the tableView. For example, if fruit are to appear in section 0 of the tableView, you can just use the tableView indexPath to lookup in the fruitFRC to get the fruit details. But for drinks, in section 1 of the tableView, you need to create a new indexPath since the drinksFRC will be using section 0. (You can use indexPathForRow:inSection: method of NSIndexPath to create the new indexPath.)

Likewise, in numberOfRowsInSection , if the section is 0, return the number of objects in fruitFRC , and if the section is 1, return the number of objects in drinksFRC .

And so on...