NSFetchedResultsController - unexpectedly found nil while unwrapping an Optional value - ios

Question

I am using NSFetchedResultsController to populate my TableView. I have an entity "HubProfile" with attributes: "Name" & "HubID"
Issue: NSFetchedResultsController is coming nil. The weird part is that when I print fetchedResultsController in viewDidLoad & cellForRowIndexPath method -- it gives a value. But in the numberOfRowsInSection method, the fetchedResultsController is nil and the app crashes.
Also the data is already saved in CoreData. I have seen it in SQLite Browser -- so there is data to load
Can't seem to figure out why.
Below is my code:
class StudentsController: UIViewController, UITableViewDataSource, UITableViewDelegate, NSFetchedResultsControllerDelegate
{
let managedContext = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
var fetchedResultsController: NSFetchedResultsController!
override func viewDidLoad() {
super.viewDidLoad()
//FETCH REQUESTS
let fetchRequest = NSFetchRequest(entityName: "HubProfile")
let sortDescriptor = NSSortDescriptor(key: "name", ascending: true)
fetchRequest.sortDescriptors = [sortDescriptor]
fetchRequest.predicate = NSPredicate(format: "hubID = %#", hubID!)
fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: managedContext, sectionNameKeyPath: nil, cacheName: nil)
fetchedResultsController.delegate = self
do
{
try! fetchedResultsController.performFetch()
}
print(fetchedResultsController) //THIS IS NOT NIL
}
//TABLEVIEWDATASOURCE PROTOCOL:
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print(fetchedResultsController) // THIS IS NIL
let sectionInfo = fetchedResultsController.sections![section] as NSFetchedResultsSectionInfo
return sectionInfo.numberOfObjects
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("cell") as! StudentsCell!
print(fetchedResultsController) //THIS is NOT Nil
let hubProfile = fetchedResultsController.objectAtIndexPath(indexPath) as! HubProfile
cell.nameLabel?.text = hubProfile.name
return cell
}}

Answer 1

The tableView may have loaded before the fetchResultsController has had a chance to load up. So reload the table as soon as you performFetch() as so:
do
{
try! fetchedResultsController.performFetch()
tableView.reloadData()
}
print(fetchedResultsController) //THIS IS NOT NIL
}
Then in your tableView function check if the fetchedResultsController is nil, if it is then give it some other value (in this example, 0) and when the table reloads after the fetch is complete, the function will take the items from your fetchResultsController (when it is != nil):
override func numberOfSections(in tableView: UITableView) -> Int {
return fetchedResultsController.sections?.count ?? 0
}