NSFetchedResultsControllerDelegate method not called when switching tab - ios

Question

My application has two tab bars. The first one presents a list of games added on view controller and save them on the core data database. Switching on the second tab/view reads from the database and presents it inside a table view. I implemented the NSFetchedResultsControllerDelegatewith a fetch method. But whenever I add or insert an item to the context on the first tab and switch to second tab, FRC delegate methods are not getting called. But when i implement the same methods on the first tab I can see them being call when I made a change to the database.
import UIKit
import CoreData
class AllWLeagueController : UITableViewController {
var fetchRequestController : NSFetchedResultsController<GameMo>!
var arrayOfGamesModel : [[GameMo]]? = []
var gameMo: GameMo?
var gamesMo: [GameMo] = []
override func viewDidLoad() {
validation(object: arrayOfGamesModel)
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
fetchRequest()
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return arrayOfGamesModel?.count ?? 0
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if let weekL = arrayOfGamesModel?[indexPath.row] {
if let cell = tableView.dequeueReusableCell(withIdentifier: "WL") as? AllWLeaguesTableViewCell {
let winCounts = WLManager.winCountMethod(from: weekL)
let lossCounts = WLManager.lossCountMethod(from:weekL)
cell.setOulet(win: winCounts, loss: lossCounts, rankName: rankString)
cellLayer(with: cell)
return cell
}
}
}
extension AllWLeagueController: NSFetchedResultsControllerDelegate {
func fetchRequest () {
let fetchRequest = NSFetchRequest<GameMo>(entityName: "Game")
fetchRequest.sortDescriptors = [NSSortDescriptor(key: "win", ascending: true)]
if let appDelegate = (UIApplication.shared.delegate as? AppDelegate){
let context = appDelegate.persistentContainer.viewContext
// fetch result controller
fetchRequestController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
fetchRequestController.delegate = self
do{
try fetchRequestController.performFetch()
if let fetchedObjects = fetchRequestController.fetchedObjects {
gamesMo = fetchedObjects
print("Fetech Request Activated")
print(gamesMo)
}
}catch{
fatalError("Failed to fetch entities: \(error)")
}
}
}
func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
print("TableView beginupdates")
tableView.beginUpdates()
}
func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
switch type {
case .insert:
if let newIndexPath = newIndexPath {
print("insert")
tableView.insertRows(at: [newIndexPath], with: .fade)
}
case .delete:
if let indexPath = indexPath {
print("delete")
tableView.deleteRows(at: [indexPath], with: .fade)
}
case .update:
if let indexPath = indexPath {
print("update")
tableView.reloadRows(at: [indexPath], with: .fade)
}
default:
tableView.reloadData()
}
if let fetchedObjects = controller.fetchedObjects {
gamesMo = fetchedObjects as! [GameMo]
}
}
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
print("TableView endupdates")
tableView.endUpdates()
}
}

Answer 1

It looks like your fetchedResultsController is updating gamesMo, but your tableView is looking at arrayOfGamesModel. But arrayOfGamesModel is never updated.
You can either change your tableView methods to look at gamesMo, or change your fetchedResultsController to update arrayOfGamesModel.