Criei uma atividade em que, quando um dos campos de texto clicou, um filho (diálogo de alerta) é exibido com a lista de produtos, mas quando clico em um item da lista, não posso exibi-lo no texto arquivado quando o alerta é descartado.

esta é a visão dos pais

import Foundation
import UIKit

class ViewAward: UIViewController{

@IBOutlet var tfMCN: UITextField!
@IBOutlet var tfAmount: UITextField!
@IBOutlet var tfProduct: UITextField!
@IBOutlet var tfTotal: UITextField!

override func viewDidLoad() {
    super.viewDidLoad()

    let rightAddBarButtonItem:UIBarButtonItem = UIBarButtonItem(title: "Send", style: UIBarButtonItemStyle.Plain, target: self, action: #selector(ViewAward.searchTapped))

    self.navigationItem.setRightBarButtonItems([rightAddBarButtonItem], animated: true)

    let state = String(ViewPopUpProduct.Product.ProductDescription)
    print("My view state:"+state)

    self.tfProduct.text = state
    tfProduct.addTarget(self, action:  #selector(ViewAward.productTapped), forControlEvents: UIControlEvents.TouchDown)

}

func searchTapped(sender:UIButton) {

    let alertController = UIAlertController(
        title: "Award",
        message:"Award successfully posted!",
        preferredStyle: UIAlertControllerStyle.Alert)
    alertController.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default,handler: nil))

    self.presentViewController(alertController, animated: true, completion: nil)
}

func productTapped(textfield: UITextField){

    //tfProduct.endEditing(true)
    tfProduct.resignFirstResponder()

    let popOverVC = UIStoryboard(name:"Main",bundle:nil).instantiateViewControllerWithIdentifier("sbPopUpID") as! ViewPopUpProduct

    self.addChildViewController(popOverVC)

    popOverVC.view.frame = self.view.frame

    self.view.addSubview(popOverVC.view)

    popOverVC.didMoveToParentViewController(self)

}
}

e isso quando o usuário clicou nos itens

import UIKit

class ViewPopUpProduct: UIViewController {

@IBOutlet var tableView: UITableView!

var productDescription = ["Product 1","Product 2","Product 3"]
var productID = ["prdct1","prdct2","prdct3"]


// Global Variables 
struct Product {
    static var ProductID = String()
    static var ProductDescription = String()
}

override func viewDidLoad() {
    super.viewDidLoad()
    self.showAnimate()
    self.view.backgroundColor = UIColor.blackColor().colorWithAlphaComponent(0.4)

    // Do any additional setup after loading the view.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

@IBAction func cancelPopUp(sender: AnyObject) {
    self.removeAnimate()
}


func showAnimate()
{
    self.view.transform = CGAffineTransformMakeScale(1.3, 1.3)
    self.view.alpha = 0.0;
    UIView.animateWithDuration(0.25, animations: {
        self.view.alpha = 1.0
        self.view.transform = CGAffineTransformMakeScale(1.0, 1.0)
    });
}

func removeAnimate()
{
    UIView.animateWithDuration(0.25, animations: {
        self.view.transform = CGAffineTransformMakeScale(1.3, 1.3)
        self.view.alpha = 0.0;
        }, completion:{(finished : Bool)  in
            if (finished)
            {
                self.view.removeFromSuperview()
            }
    });
}

//Mark - Table View

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

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = self.tableView.dequeueReusableCellWithIdentifier("cell",forIndexPath: indexPath) as! ProductViewCell

    cell.productLabel.text = productDescription[indexPath.row]

    return cell
}

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {

    tableView.deselectRowAtIndexPath(indexPath, animated: true)

    Product.ProductID = String(productID[indexPath.row])
    Product.ProductDescription = String(productDescription[indexPath.row])

    self.removeAnimate()

}

}