Can't load data from CoreData into tableview - ios

Question

I'm learning how to use CoreData. I have a tableView with an add button, which segues to a view with just a textfield and a save button. When the button is pressed, the string in the textfield is saved in a CoreData database:
#IBOutlet weak var name: UITextField!
#IBAction func onSave(sender: UIBarButtonItem) {
saveItem(name.text!)
self.dismissViewControllerAnimated(true, completion: nil)
}
private func saveItem(itemName: String)
{
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let entity = NSEntityDescription.entityForName("Item", inManagedObjectContext: managedContext)
let item = NSManagedObject(entity: entity!, insertIntoManagedObjectContext: managedContext)
item.setPrimitiveValue(itemName, forKey: "name")
do {
try managedContext.save()
listItems.append(item)
}catch let error {
print(error)
}
The tableView file has the Controller class and a global array of NSManagedObject:
Here is the relevant code:
var listItems = [NSManagedObject]()//outside the class
override func viewWillAppear(animated: Bool) { //in the tableviewcontroller class
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let fetch = NSFetchRequest(entityName: "Item")
do {
let results = try managedContext.executeFetchRequest(fetch)
listItems = results as! [NSManagedObject]
//EDIT
for item in listItems {
print(item)
}
} catch let error {
print(error)
}
self.tableView.reloadData()
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath)
let item = listItems[indexPath.row]
cell.textLabel?.text = item.valueForKey("name") as? String
return cell
}
The database is very simple: an Entity named Item with a name attribute
This, however, doesn't work. When I press the save button, no new rows are added. If I remove all the code in viewWillAppear but self.tableView.reloadData(), the rows are created but when I relaunch the app they aren't there.
Any help would be much appreciated.