NSFetchedResultsControllerDelegate : controllerDidChangeContent not working in iOS 8 - ios

Question

I am tryin to use NSFetchedResultsController in a UITableView.. But for some reason the NSFetchedResultsControllerDelegate are not getting fired when I add a new entry. Here is the complete code
import UIKit
import CoreData
let coreDataStack = CoreDataStack()
class CDListViewController: UITableViewController, NSFetchedResultsControllerDelegate {
var fetchedResultsController: NSFetchedResultsController {
if _fetchedResultsController != nil {
return _fetchedResultsController!
}
let fRequest = fetchRequest()
let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fRequest, managedObjectContext: coreDataStack.managedObjectContext!, sectionNameKeyPath: nil, cacheName: nil)
aFetchedResultsController.delegate = self
_fetchedResultsController = aFetchedResultsController
var error: NSError? = nil
if !_fetchedResultsController!.performFetch(&error) {
}
println(error)
return _fetchedResultsController!
}
var _fetchedResultsController: NSFetchedResultsController? = nil
func fetchRequest() -> NSFetchRequest {
let fetchRequest = NSFetchRequest(entityName: "Menu")
// Set the batch size to a suitable number.
fetchRequest.fetchBatchSize = 2
// Edit the sort key as appropriate.
let sortDescriptor = NSSortDescriptor(key: "createdAt", ascending: false)
fetchRequest.sortDescriptors = [sortDescriptor]
return fetchRequest
}
override func viewDidLoad() {
super.viewDidLoad()
fetchedResultsController.delegate = self
print(fetchedResultsController)
// fetchedResultsController?.performFetch(nil)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
override func tableView(tableView: UITableView, editingStyleForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCellEditingStyle {
return UITableViewCellEditingStyle.Delete
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let menus = fetchedResultsController.fetchedObjects as [Menu]
return menus.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as UITableViewCell
let curr = fetchedResultsController.objectAtIndexPath(indexPath) as Menu
// Configure the cell...
cell.textLabel?.text = curr.text
return cell
}
// Override to support conditional editing of the table view.
override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
// Return NO if you do not want the specified item to be editable.
return true
}
// Override to support editing the table view.
func controllerWillChangeContent(controller: NSFetchedResultsController) {
println("Coming in here")
self.tableView.beginUpdates()
}
func controllerDidChangeContent(controller: NSFetchedResultsController) {
self.tableView.endUpdates()
}
// Override to support editing the table view.
override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
let entry = self.fetchedResultsController.objectAtIndexPath(indexPath) as Menu
coreDataStack.managedObjectContext?.deleteObject(entry)
coreDataStack.saveContext()
}
func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
switch(type) {
case NSFetchedResultsChangeType.Insert : self.tableView.insertRowsAtIndexPaths([newIndexPath!], withRowAnimation: UITableViewRowAnimation.Automatic)
break
case NSFetchedResultsChangeType.Delete : self.tableView.deleteRowsAtIndexPaths([indexPath!], withRowAnimation: UITableViewRowAnimation.Automatic)
break
case NSFetchedResultsChangeType.Update : self.tableView.reloadRowsAtIndexPaths([indexPath!], withRowAnimation: UITableViewRowAnimation.Automatic)
default:
println("Nothing")
}
}
func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {
switch(type) {
case NSFetchedResultsChangeType.Insert : self.tableView.insertSections(NSIndexSet(index: sectionIndex), withRowAnimation: UITableViewRowAnimation.Automatic)
break
case NSFetchedResultsChangeType.Delete : self.tableView.deleteSections(NSIndexSet(index: sectionIndex), withRowAnimation: UITableViewRowAnimation.Automatic)
break
default:
println("Nothing")
}
}
}
When I add an entry to the context and save the content neither controllerWillChangeContent nor controllerDidChangeContent is being called. I made sure that the context is saved because if I restart the app I can see the recently added entry.
Can anyone find any issue with the code written above?

Answer 1

I noticed you set the delegate twice. Once inside the computed property and once in the viewDidLoad. I think your issue may arise from the fact that you set it for aFetchedResultsController in the computed property first, and thus, the delegate methods are called when aFetchedResultsController's delegate methods are called (which they are not). Deleting the delegation assignment (aFetchedResultsController.delegate = self) in your computed property should resolve this issue.