swift - NSPredicate and Context Save is not working well - ios

Question

I have a function that checking core data. if doesn't exist it should write to in it(but its not working in that way) SoundItems is an array that contains favorited objects and mainArray is the array that contains real objects;
#IBAction func Favori(_ sender: Any) {
// save core data
let app = UIApplication.shared.delegate as! AppDelegate
let context = app.persistentContainer.viewContext
let newSound = NSEntityDescription.entity(forEntityName: "Sounds", in: context)
let sound = NSManagedObject(entity: newSound!, insertInto: context)
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Sounds")
let predicate = NSPredicate(format: "soundName = %#", soundArray[soundIndex].deletingPathExtension().lastPathComponent)
fetchRequest.predicate = predicate
do {
let fetchResults = try context.fetch(fetchRequest) as? [Sounds]
if fetchResults!.count > 0 {
print("already favd")
}
else {
sound.setValue(soundArray[soundIndex].deletingPathExtension().lastPathComponent, forKey: "soundName")
try context.save()
soundItems.append(sound)
print(sound)
}
}
catch {
print(error)
}
}
and here is the code that listing the core data;
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
let cell = tableView.dequeueReusableCell(withIdentifier: "cell")! as UITableViewCell
let sound = soundItems[indexPath.row]
cell.textLabel?.text = sound.value(forKey: "soundName") as? String
return cell
}
I tried to run the code in debug mode and it works fine when there is no duplicated core data and adds into the tableView list. But here is the situation; when core data exist(fetchResults!.count > 0) still adding in the tableview as nil label.text but always adds the item of mainArray[0]

Answer 1

If you want to check if the sound is in the favorites and if not add a new sound you have to change the order of the steps
#IBAction func Favori(_ sender: Any) {
// save core data
let app = UIApplication.shared.delegate as! AppDelegate
let context = app.persistentContainer.viewContext
let fetchRequest : NSFetchRequest<Sounds> = Sounds.fetchRequest()
let favName = soundArray[soundIndex].deletingPathExtension().lastPathComponent
let predicate = NSPredicate(format: "soundName = %#", favName)
fetchRequest.predicate = predicate
do {
let fetchResults = try context.fetch(fetchRequest)
if fetchResults.isEmpty {
let newSound = NSEntityDescription.insertNewObject(forEntityName: "Sounds", into:context) as! Sounds
newSound.soundName = favName
try context.save()
soundItems.append(newSound)
print(newSound)
}
else {
print("already favd")
}
}
catch {
print(error)
}
}
It's recommended to name entities in singular form (Sound).

Answer 2

#vadian had the point. Why did you insert a new sound before fetching the data?
let newSound = NSEntityDescription.entity(forEntityName: "Sounds", in: context)
let sound = NSManagedObject(entity: newSound!, insertInto: context)