CoreData info are not shown in the table cell - ios

Question

I have a custom cell and using core data the cell is not updating.
At first i created some entities at the .xcdatamodeId with a Manual/None Codegen option. The project would not build and would give me this error:
'An NSManagedObject of class 'DreamLister.Item' must have a valid NSEntityDescription.'
After i went to the generated class files for my model and deleted all the #objc(Item) lines, the project was build but nothing would come up in the cells of the simulator. The custom cell has an identifier that is used in the code for the cellForRowAt function, also i am generating test data and i access the AppDelegate like this
let ad = UIApplication.shared.delegate as! AppDelegate
let context = ad.persistentContainer.viewContext
edit: after an answer suggested to change the codegen option to Class Definition the build fails with a Swift compile error:
Command: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc failed with exit code 1
here is the code of my controller
import UIKit
import CoreData
class MainVC: UIViewController, UITableViewDelegate, UITableViewDataSource, NSFetchedResultsControllerDelegate {
#IBOutlet weak var tableView: UITableView!
#IBOutlet weak var segment: UISegmentedControl!
var controller: NSFetchedResultsController<Item>!
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
generateTestData()
attemptFetch()
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ItemCell", for: indexPath) as! ItemCell
configureCell(cell: cell, indexPath: indexPath as NSIndexPath)
return cell
}
func configureCell(cell: ItemCell, indexPath: NSIndexPath) {
let item = controller.object(at: indexPath as IndexPath)
cell.configureCell(item: item)
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
if let objs = controller.fetchedObjects , objs.count > 0 {
let item = objs[indexPath.row]
performSegue(withIdentifier: "ItemDetailsVC", sender: item)
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "ItemDetailsVC" {
if let destination = segue.destination as? ItemDetailsVC {
if let item = sender as? Item {
destination.itemToEdit = item
}
}
}
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let sections = controller.sections {
let sectionInfo = sections[section]
return sectionInfo.numberOfObjects
}
return 0
}
func numberOfSections(in tableView: UITableView) -> Int {
return 0
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 150
}
func attemptFetch() {
let fetchRequest: NSFetchRequest<Item> = Item.fetchRequest()
let dateSort = NSSortDescriptor(key: "created", ascending: false)
fetchRequest.sortDescriptors = [dateSort]
let controller = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
controller.delegate = self
self.controller = controller
do {
try controller.performFetch()
} catch {
let error = error as NSError
print("\(error)")
}
}
func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableView.beginUpdates()
}
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableView.endUpdates()
}
func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
switch(type) {
case.insert:
if let indexPath = newIndexPath {
tableView.insertRows(at: [indexPath], with: .fade)
}
break
case.delete:
if let indexPath = indexPath {
tableView.deleteRows(at: [indexPath], with: .fade)
}
break
case.update:
if let indexPath = indexPath {
let cell = tableView.cellForRow(at: indexPath) as! ItemCell
configureCell(cell: cell, indexPath: indexPath as NSIndexPath)
}
break
case.move:
if let indexPath = indexPath {
tableView.deleteRows(at: [indexPath], with: .fade)
}
if let indexPath = newIndexPath {
tableView.insertRows(at: [indexPath], with: .fade)
}
break
}
}
func generateTestData() {
let item = Item(context: context)
item.title = "MacBook Pro"
item.price = 1800
item.details = "I can't wait until the September event, I hope they release new MPBs"
let item2 = Item(context: context)
item2.title = "Bose Headphones"
item2.price = 300
item2.details = "But man, its so nice to be able to block out everyone with the noise canceling tech."
let item3 = Item(context: context)
item3.title = "Tesla Model S"
item3.price = 110000
item3.details = "Oh man this is a beautiful car. And one day, I willl own it"
ad.saveContext()
}
}
the code for the ItemCell
import UIKit
class ItemCell: UITableViewCell {
#IBOutlet weak var thumb: UIImageView!
#IBOutlet weak var title: UILabel!
#IBOutlet weak var price: UILabel!
#IBOutlet weak var details: UILabel!
func configureCell(item: Item) {
self.title.text = item.title
self.price.text = "$\(item.price)"
self.details.text = item.details
}
}
and the code of the core data generated files
Item+CoreDataClass.swift
import Foundation
import CoreData
public class Item: NSManagedObject {
public override func awakeFromInsert() {
super.awakeFromInsert()
self.created = NSDate()
}
}
Item+CoreDataProperties.swift
import Foundation
import CoreData
extension Item {
#nonobjc public class func fetchRequest() -> NSFetchRequest<Item> {
return NSFetchRequest<Item>(entityName: "Item");
}
#NSManaged public var created: NSDate?
#NSManaged public var details: String?
#NSManaged public var title: String?
#NSManaged public var price: Double
#NSManaged public var toImage: Image?
#NSManaged public var toItemType: ItemType?
#NSManaged public var toStore: Store?
}
Any thoughts or ideas?
Thanks in Advance.

Answer 1

In core data file Select Entity and Select Codegen option to Class defination and run and see

Answer 2

I deleted and created the generated files for the core data again and i also change the return statements of these two functions on the MainVC from returning zero to this.
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let sections = controller.sections {
let sectionInfo = sections[section]
return sectionInfo.numberOfObjects
} else {
return 0
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}