NSFetchedResultsController can't update the tableView swift4 - core-data

Question

I'm trying to make it work for last couple of days and can't get it working. Its something tiny detail obviously I can't seem to find.
Could you take a look and give me some insights about my code?
I'm trying to update the logView with app savings in the coredata.
Here's the entire code for ViewController and CoreData Handler.
/// fetch controller
lazy var fetchController: NSFetchedResultsController = { () -> NSFetchedResultsController<NSFetchRequestResult> in
let entity = NSEntityDescription.entity(forEntityName: "Logs", in: CoreDataHandler.sharedInstance.backgroundManagedObjectContext)
let fetchRequest = NSFetchRequest<NSFetchRequestResult>()
fetchRequest.entity = entity
let nameDescriptor = NSSortDescriptor(key: "name", ascending: false)
fetchRequest.sortDescriptors = [nameDescriptor]
let fetchedController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: CoreDataHandler.sharedInstance.backgroundManagedObjectContext, sectionNameKeyPath: "duration", cacheName: nil)
fetchedController.delegate = self as? NSFetchedResultsControllerDelegate
return fetchedController
}()
override func viewDidLoad() {
title = "Week Log"
tableView.tableFooterView = UIView(frame: CGRect.zero)
tableView.separatorColor = UIColor.black
tableView.backgroundColor = UIColor.red
refreshView()
loadNormalState()
loadCoreDataEntities()
}
/**
Refresh the view, reload the tableView.
*/
func refreshView() {
loadCoreDataEntities()
tableView.reloadData()
}
/**
Load history entities from core data. (I'm printing on the console and
be able to see the the fetched data but I can't load it to tableView.)
*/
func loadCoreDataEntities() {
do {
try fetchController.performFetch()
} catch {
print("Error occurred while fetching")
}
}
import Foundation
import CoreData
class CoreDataHandler: NSObject {
/**
Creates a singleton object to be used across the whole app easier
- returns: CoreDataHandler
*/
class var sharedInstance: CoreDataHandler {
struct Static {
static var instance: CoreDataHandler = CoreDataHandler()
}
return Static.instance
}
lazy var backgroundManagedObjectContext: NSManagedObjectContext = {
let backgroundManagedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
let coordinator = self.persistentStoreCoordinator
backgroundManagedObjectContext.persistentStoreCoordinator = coordinator
return backgroundManagedObjectContext
}()
lazy var objectModel: NSManagedObjectModel = {
let modelPath = Bundle.main.url(forResource: "Model", withExtension: "momd")
let objectModel = NSManagedObjectModel(contentsOf: modelPath!)
return objectModel!
}()
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
let persistentStoreCoordinator = NSPersistentStoreCoordinator(managedObjectModel: self.objectModel)
// Get the paths to the SQLite file
let storeURL = self.applicationDocumentsDirectory().appendingPathComponent("Model.sqlite")
// Define the Core Data version migration options
let options = [NSMigratePersistentStoresAutomaticallyOption: true, NSInferMappingModelAutomaticallyOption: true]
// Attempt to load the persistent store
var error: NSError?
var failureReason = "There was an error creating or loading the application's saved data."
do {
try persistentStoreCoordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: storeURL, options: options)
} catch {
// Report any error we got.
var dict = [String: AnyObject]()
dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject
dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject
dict[NSUnderlyingErrorKey] = error as NSError
let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
// Replace this with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
abort()
}
return persistentStoreCoordinator
}()
func applicationDocumentsDirectory() -> NSURL {
return FileManager.default.urls(for: FileManager.SearchPathDirectory.documentDirectory, in: FileManager.SearchPathDomainMask.userDomainMask).last! as NSURL
}
func saveContext() {
do {
try backgroundManagedObjectContext.save()
} catch {
print("Error while saving the object context")
// Error occured while deleting objects
}
}

Answer 1

You have a data source delegate somewhere. That data source delegate tells the table view how many items there are, and what their contents is. How does it know how many items? That must be stored somewhere.
When the fetch controller is successful, it must modify the data that the data source delegate relies on in some way, and then call reloadData. Are you doing this? Are you doing anything that causes the data source delegate to change the number of items it reports?
And calling loadCoreDataEntities, immediately followed by reloadData, is nonsense. loadCoreDataEntities is asynchronous. By the time you call reloadData, it hasn't loaded any entities yet. realodData is called when loadCoreDataEntities has finished.