unabe to Reload data in tableview via userdefault - swift

Question

I am a newbie and learning ios programming. I have made a custom table view cell. I am trying to append data in it via user defaults but its not storing the data, every time i go back the app refreshes making the table view blank screen.
// data sent from here
class ViewController: UIViewController {
#IBOutlet weak var textfield: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
#IBAction func submit(_ sender: AnyObject) {
performSegue(withIdentifier: "move", sender: nil)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let destination = segue.destination as? secondviewcontroller
destination?.list.append(textfield.text!)
let defaults = UserDefaults.standard
defaults.set(destination?.list, forKey: "listarray")
UserDefaults.standard.synchronize()
}
}
// here i want to retreive
class secondviewcontroller: UIViewController {
#IBOutlet weak var tblView: UITableView!
var list = ["fahad","Ali","tahir"]
var abc = ""
override func viewDidLoad() {
super.viewDidLoad()
tblView.dataSource = self;
tblView.delegate = self;
let storedarray = UserDefaults.standard.object(forKey: "listarray")
print("hi\(storedarray)")
}
override func viewDidAppear(_ animated: Bool) {
tblView.register(TableViewCell.self, forCellReuseIdentifier: "TableViewCell")
tblView.reloadData()
}
#IBAction func backbtn(_ sender: AnyObject) {
dismiss(animated: true, completion: nil)
}
}
import UIKit
class secondviewcontroller: UIViewController {
#IBOutlet weak var tblView: UITableView!
var list = ["fahad","Ali","tahir"]
var abc = ""
override func viewDidLoad() {
super.viewDidLoad()
tblView.dataSource = self;
tblView.delegate = self;
}
override func viewDidAppear(_ animated: Bool) {
tblView.register(TableViewCell.self, forCellReuseIdentifier: "TableViewCell")
let storedarray = UserDefaults.standard.object(forKey: "listarray")
print("hi\(storedarray)")
tblView.reloadData()
}
#IBAction func backbtn(_ sender: AnyObject) {
dismiss(animated: true, completion: nil)
}
}
extension secondviewcontroller : UITableViewDataSource , UITableViewDelegate{
func numberOfSections(in tableView: UITableView) -> Int {
return 1;
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print (list)
return list.count;
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
var cell = tableView.dequeueReusableCell(withIdentifier: "TableViewCell", for: indexPath) as! TableViewCell;
cell.textlabel.text = list[indexPath.row];
return cell;
}
}
// my custom table view
import UIKit
class TableViewCell: UITableViewCell {
#IBOutlet weak var textlabel: UILabel!
override func awakeFromNib() {
super.awakeFromNib()
}
}
My UI storyboardgetting this error

Answer 1

you must subclass the UITableViewDelegate and UITableViewDataSource methods and implement the required methods for it to display the data in your custom view.
refer to this: http://clean-swift.com/refactoring-table-view-data-source-and-delegate-methods/
try adding the code for stored array into the viewwillappear method..

Answer 2

These lines recreates the same list with an new element without considering the saved items:
destination?.list.append(textfield.text!)
let defaults = UserDefaults.standard
defaults.set(destination?.list, forKey: "listarray")
UserDefaults.standard.synchronize()
You should instead:
let newEntry = textfield.text!
let defaults = UserDefaults.standard
if destination?.list.count == 3 { //3 because you hardcoded 3 items in next controller
destination?.list.append(newEntry)
} else {
let obj = defaults.object(forKey: "listarray") as? [String] ?? [String]()
destination?.list = obj.append(newEntry)
}
defaults.set(destination?.list, forKey: "listarray")
UserDefaults.standard.synchronize()