Preserve data in table from a View to another - ios

Question

I'm trying to send values from one view to other and print them in a table as an array. The program work and display the data but the problem is that when I try to add another value to the table when I return to the view that have the table the previous values are no longer there.
In this segment of code I sent the data to the other view
import UIKit
class NewContactoViewController: UIViewController, UITextFieldDelegate {
var contacto: String = ""
var numero: String = ""
#IBOutlet weak var contactoField: UITextField!
#IBOutlet weak var numField: UITextField!
let defaultValues = UserDefaults.standard
#IBAction func addButton(_ sender: UIButton) {
contacto = contactoField.text!
numero = numField.text!
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
var secondController = segue.destination as! ContactosViewController
secondController.contactos = contactoField.text!
secondController.numerosmov = numField.text!
}
override func viewDidLoad() {
super.viewDidLoad()
self.contactoField.delegate = self
self.numField.delegate = self
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
In this segment of code are the tableviews that display the data
import UIKit
class ContactosViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
let defaultValues = UserDefaults.standard
var contactos: String = ""
var numerosmov: String = ""
var tablacontacto = [String] ()
var tablanumero = [String] ()
let cellIdentifier: String = "cell"
let cellIdentifier2: String = "cell2"
#IBOutlet weak var contactoTable: UITableView!
#IBOutlet weak var numTable: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
let backButton = UIBarButtonItem(title: "", style: UIBarButtonItemStyle.plain, target: navigationController, action: nil)
navigationItem.leftBarButtonItem = backButton
// Do any additional setup after loading the view.
datosRecividos(contactos, numerosmov)
contactoTable.delegate = self
numTable.delegate = self
contactoTable.dataSource = self
numTable.dataSource = self
contactoTable!.reloadData()
numTable!.reloadData()
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
contactoTable.reloadData()
numTable.reloadData()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func datosRecividos(_ contactosr: String, _ numerosr: String)
{
tablacontacto.append(contactosr)
tablanumero.append(numerosr)
let usercontacto = defaultValues.array(forKey: "contactoTable")
let usernumero = defaultValues.array(forKey: "numeroTable")
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if (tableView.tag == 1)
{
return(tablacontacto.count)
}
else if (tableView.tag == 2)
{
return(tablanumero.count)
}
return 0
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier, for: indexPath)
if (tableView.tag == 1)
{
cell.textLabel?.text = tablacontacto[indexPath.row] as! String
}
else if (tableView.tag == 2)
{
cell.textLabel?.text = tablanumero[indexPath.row] as! String
}
return(cell)
}
}

Answer 1

There are several things wrong here, I would suggest reading again about tableView's (especially the "Load Initial Data" section) -
https://developer.apple.com/library/content/referencelibrary/GettingStarted/DevelopiOSAppsSwift/CreateATableView.html
Your tables are getting data from the "tablacontacto" and "tablanumero" arrays.
There is no place in the code you sent to populate these arrays. (Do you see anything when these tables are on screen?)
Plus You are updating these arrays with only in the "func datosRecividos(_ contactosr: String, _ numerosr: String)" -
This method is only called once in the viewDidLoad and it is not called when you segue back to this screen
Plus you have no place you get data to your arrays from your userDefaults and there is no place you save the "new" data from "NewContactoViewController" to your userDefaults.

Answer 2

Make this two variables as static variables
internal static var CONTACTTO: String = ""
internal static var NUMERO: String = ""
then access this variables using,
NewContactoViewController.CONTACTTO
NewContactoViewController.NUMERO
Then there is no need sending this values using
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
var secondController = segue.destination as! ContactosViewController
secondController.contactos = contactoField.text!
secondController.numerosmov = numField.text!
}
Or otherwise you can save these values in shared preferences

Answer 3

You can declare a delegate for data changing in NewContactoViewController
import UIKit
//Create a delegate for data changing
protocol ContactChageDelegate: class {
func contactChanged(newContact: String, newNumber: String)
}
class NewContactoViewController: UIViewController, UITextFieldDelegate {
//declare delegate variable
weak var contactChageDelegate: ContactChageDelegate?
...
#IBAction func addButton(_ sender: UIButton) {
contacto = contactoField.text!
numero = numField.text!
//if need notify data changing. maybe it will not change
//if data change {
self.contactChageDelegate.contactChanged(newContact: contacto, newNumber: numero)
//}
}
and use this delegate in ContactosViewController like this:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
//let self to delegate
if let newContactoViewController = segue.destination as? NewContactoViewController {
newContactoViewController.contactChageDelegate = self
}
}
...
//implement delegate method
extension ContactosViewController: ContactChageDelegate {
internal func contactChanged(newContact: String, newNumber: String) {
//now you have new values
//change your data array
//and reload table
}
}