prepareForSegue with custom Swift NSManagedObject : custom class crash? - ios

Question

the fetchedresultController does not return my custom nsmanagedObject in prepareForSegue.
When I add a new entry in my tableView (the "+" button that calls "insertNewObject"), the correct name, from my custom object, appears, with the correct text. But when I click on the line to perform the segue, there is a crash, exc breakpoint, I click on continue, and the program continues without adding more information.
The code to cast the nsmanagedObject as a Section class :
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "showDetail" {
if let indexPath = self.tableView.indexPathForSelectedRow() {
println("idx: \(indexPath) , objet : \(self.fetchedResultsController.objectAtIndexPath(indexPath))") //outputs ""
let object = self.fetchedResultsController.objectAtIndexPath(indexPath) as Section//NSManagedObject
let controller = (segue.destinationViewController as UINavigationController).topViewController as DetailViewController
//controller.detailItem = object
controller.navigationItem.leftBarButtonItem = self.splitViewController?.displayModeButtonItem()
controller.navigationItem.leftItemsSupplementBackButton = true
}
}
}
var fetchedResultsController: NSFetchedResultsController {
if _fetchedResultsController != nil {
return _fetchedResultsController!
}
let fetchRequest = NSFetchRequest()
let entity = NSEntityDescription.entityForName("Section", inManagedObjectContext: self.managedObjectContext!)
fetchRequest.entity = entity
fetchRequest.fetchBatchSize = 20
let sortDescriptor = NSSortDescriptor(key: "name", ascending: false)
let sortDescriptors = [sortDescriptor]
fetchRequest.sortDescriptors = [sortDescriptor]
let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.managedObjectContext!, sectionNameKeyPath: nil, cacheName: nil)
aFetchedResultsController.delegate = self
_fetchedResultsController = aFetchedResultsController
var error: NSError? = nil
if !_fetchedResultsController!.performFetch(&error) {
abort()
}
return _fetchedResultsController!
}
var _fetchedResultsController: NSFetchedResultsController? = nil
func insertNewObject(sender: AnyObject) { //this works
let context = self.fetchedResultsController.managedObjectContext
let entity = self.fetchedResultsController.fetchRequest.entity!
let newManagedObject = NSEntityDescription.insertNewObjectForEntityForName(entity.name!, inManagedObjectContext: context) as Section
newManagedObject.name = String("insert")
var error: NSError? = nil
if !context.save(&error) {
abort()
}
}
func configureCell(cell: UITableViewCell, atIndexPath indexPath: NSIndexPath) {
let section = self.fetchedResultsController.objectAtIndexPath(indexPath) as Section
cell.textLabel.text = section.name;//this works
}