How to add a DatePicker to my AlertAction and Save to CoreData

I currently have an app that logs your weight using a tableview and coredata, which is 100% working! I'm attempting to add a datepicker in the UIAlertAction and save it using CoreData as well as display it as a subtitle in my tableview. I have already added it to the datamodel entity but how do i add it to the alertaction and then save it as the tableview subtitle? Below is my current working code:

class seventhViewController: UIViewController, UITextFieldDelegate, UITableViewDataSource, UITableViewDelegate {


  @IBOutlet weak var tableView: UITableView!

  var itemName: [NSManagedObject] = []

  override func viewDidLoad() {
  super.viewDidLoad()

  }

  override func viewWillAppear(_ animated: Bool) {
  super.viewWillAppear(animated)

  guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
  return
  }
  let context = appDelegate.persistentContainer.viewContext
  let fetchRequest = NSFetchRequest(entityName: "Title")

  do
  {
  itemName = try context.fetch(fetchRequest)
  }
  catch
  {
  print("Error loading data")
  }
  }

  var titleTextField: UITextField!

  func titleTextField(textfield: UITextField){
  titleTextField = textfield
  titleTextField.placeholder = "enter weight here"
  }

  @IBAction func addButton(_ sender: Any) {
  let alert = UIAlertController(title: "Add Weight", message: "", preferredStyle: .alert)
  let addAction = UIAlertAction(title: "Save", style: .default, handler: self.save)
  let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)
  alert.addAction(addAction)
  alert.addAction(cancelAction)
  alert.addTextField(configurationHandler: titleTextField)
  self.present(alert, animated: true, completion: nil)
  }

  func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
  if editingStyle == UITableViewCell.EditingStyle.delete {
  let appDelegate = UIApplication.shared.delegate as! AppDelegate
  let context = appDelegate.persistentContainer.viewContext
  context.delete(itemName[indexPath.row])
  itemName.remove(at: indexPath.row)

  do
  {
  try context.save()
  }
  catch
  {
  print("There was an error in deleting.")
  }
  }
  self.tableView.reloadData()
  }

  func save(alert: UIAlertAction!) {
  let appDelegate = UIApplication.shared.delegate as! AppDelegate
  let context = appDelegate.persistentContainer.viewContext
  let entity = NSEntityDescription.entity(forEntityName: "Title", in: context)!
  let theTitle = NSManagedObject(entity: entity, insertInto: context)
  theTitle.setValue(titleTextField.text, forKey: "title")

  do
  {
  try context.save()
  itemName.append(theTitle)
  }
  catch
  {
  print("There was an error in saving.")
  }
  self.tableView.reloadData()
  }

  func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
  return itemName.count
  }

  func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
  let title = itemName[indexPath.row]
  let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
  cell.textLabel?.text = title.value(forKey: "title") as? String
  cell.textLabel?.textColor = UIColor.white
  return cell
  }
}