Appending Values Consistently in Swift - ios

Question

EDIT: Just changing the code to show my attempt at the Singleton suggestion.
So I am attempting to create an application which would take the selection of a user from a UITableView and pass that to another UITableView. Then, it would be appended to the array in that view and presented as the new table. The idea being that users can select from multiple lists and create one list made of all their selections.
However, I am extremely new to iOS development and while I can get it to let me take the selected value and show it in the new UITableView, it only sends the one value and does not keep or append it. Meaning I can never show multiple additions to the list.
So, what I'm getting atm is the ability to select a cell, let's say "Kevin Smith", and that value gets sent to the new UITableView and shown to the user. But if I go and select another value, "John Smith", then only John shows up and Kevin is gone.
Here is my three controllers involved:
The first UITAbleView Controller
class PlayerViewController: UITableViewController {
var resultsController: NSFetchedResultsController<Player>!
let CDSPlayer = coreDataStackPlayer()
override func viewDidLoad() {
super.viewDidLoad()
tableView.allowsMultipleSelection = true
let request: NSFetchRequest<Player> = Player.fetchRequest()
let sortDescriptor = NSSortDescriptor(key: "level", ascending: true)
request.sortDescriptors = [sortDescriptor]
resultsController = NSFetchedResultsController(
fetchRequest: request,
managedObjectContext: CDSPlayer.managedContext,
sectionNameKeyPath: nil,
cacheName: nil
)
resultsController.delegate = self
do{
try resultsController.performFetch()
} catch {
print("Perform Fetch Error: \(error)")
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of rows
return resultsController.sections?[section].numberOfObjects ?? 0
}
override func tableView(_ _tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell{
let cell = tableView.dequeueReusableCell(withIdentifier: "PlayerCell", for: indexPath)
let selectedIndexPaths = tableView.indexPathsForSelectedRows
let rowIsSelected = selectedIndexPaths != nil && selectedIndexPaths!.contains(indexPath)
cell.accessoryType = rowIsSelected ? .checkmark : .none
let player = resultsController.object(at: indexPath)
cell.textLabel?.text = player.name
return cell
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
performSegue(withIdentifier: "player2form", sender: tableView.cellForRow(at: indexPath))
}
override func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
let action = UIContextualAction(style:.destructive, title: "Delete"){(action, view, completion) in
let player = self.resultsController.object(at: indexPath)
self.resultsController.managedObjectContext.delete(player)
do {
try self.resultsController.managedObjectContext.save()
self.errorMessage(message: "Player Character Deleted.");
completion(true)
} catch {
print("Delete Failed: \(error)")
self.errorMessage(message: "Failed to Delete Player Character.");
completion(false)
}
}
action.image = UIImage(named: "trash")
action.backgroundColor = .red
return UISwipeActionsConfiguration(actions: [action])
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?){
if let _ = sender as? UIBarButtonItem, let vc = segue.destination as? AddPlayerViewController{
vc.managedContext = resultsController.managedObjectContext
}
if let cell = sender as? UITableViewCell, let vc = segue.destination as? AddPlayerViewController{
vc.managedContext = resultsController.managedObjectContext
if let indexPath = tableView.indexPath(for: cell){
let player = resultsController.object(at: indexPath)
Service.shared.allPlayers.append(player)
vc.player = player
}
}
}
//Error Function
func errorMessage(message:String){
let alert = UIAlertController(title: "Alert", message: message, preferredStyle:UIAlertControllerStyle.alert);
let okAction = UIAlertAction(title:"Ok", style:UIAlertActionStyle.default, handler:nil);
alert.addAction(okAction);
self.present(alert, animated: true, completion:nil);
}
}
extension PlayerViewController: NSFetchedResultsControllerDelegate{
func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableView.beginUpdates()
}
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableView.endUpdates()
}
func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
switch type{
case .insert:
if let indexPath = newIndexPath{
tableView.insertRows(at: [indexPath], with: .automatic)
}
case .delete:
if let indexPath = indexPath{
tableView.deleteRows(at: [indexPath], with: .automatic)
}
case .update:
if let indexPath = indexPath, let cell = tableView.cellForRow(at: indexPath){
let player = resultsController.object(at: indexPath)
cell.textLabel?.text = player.name
}
default:
break
}
}
The Selection view that passes the data:
class AddPlayerViewController: UIViewController {
var managedContext: NSManagedObjectContext!
var player: Player?
var selectedItems = [String]()
#IBOutlet weak var done_btn: UIButton!
#IBOutlet weak var playerInput: UITextField!
#IBOutlet weak var cancel_btn: UIButton!
#IBAction func add2combat(_ sender: UIButton) {
self.performSegue(withIdentifier: "player2combat", sender: self)
}
#IBAction func done(_ sender: UIButton) {
guard let name = playerInput.text, !name.isEmpty else {
return //Add notice user cannot save empty items
}
if let player = self.player {
player.name = name
} else {
//Set values from input to the cell
let player = Player(context: managedContext)
player.name = name
}
do {
try managedContext.save()
playerInput.resignFirstResponder()
dismiss(animated: true)
} catch {
print("Error Saving Player Character: \(error)")
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?){
if segue.identifier == "player2combat" {
let selectedItems : [String] = [playerInput.text!]
let otherVc = segue.destination as! CombatSceneViewController
otherVc.selectedItems = selectedItems
print(selectedItems)
}
}
#IBAction func cancel(_ sender: UIButton) {
playerInput.resignFirstResponder()
dismiss(animated: true)
}
override func viewDidLoad() {
super.viewDidLoad()
playerInput.becomeFirstResponder()
if let player = player {
playerInput.text = player.name
playerInput.text = player.name
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
And the UITableView that gets the data and tries to append it to the existing Array.
class CombatSceneViewController: UITableViewController{
var selectedItems = Service.shared.allSelectedItems
override func viewDidLoad() {
super.viewDidLoad()
let otherVC = AddPlayerViewController()
selectedItems.append(contentsOf: otherVC.selectedItems)
saveData()
loadData()
print(selectedItems)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return selectedItems.count
}
override func tableView(_ _tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell{
let cell = tableView.dequeueReusableCell(withIdentifier: "CombatCell", for: indexPath as IndexPath)
cell.textLabel?.text = selectedItems[indexPath.item]
return cell
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
tableView.reloadData()
}
func saveData() {
let data = NSMutableData()
// 1
let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
let path = paths[0]
let file = (path as NSString).appendingPathComponent("Persistent.plist")
//2
let archiver = NSKeyedArchiver(forWritingWith: data)
archiver.encode(selectedItems, forKey: "Agents")
archiver.finishEncoding()
data.write(toFile: file, atomically: true)
}
func loadData() {
let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
let path = paths[0]
let file = (path as NSString).appendingPathComponent("Persistent.plist")
// 1
if FileManager.default.fileExists(atPath: file) {
if let data = NSData(contentsOfFile: file) {
let unarchiver = NSKeyedUnarchiver(forReadingWith: data as Data)
selectedItems = unarchiver.decodeObject(forKey: "Agents") as! [String]
unarchiver.finishDecoding()
}
}
}
Singleton Class:
class Service {
static let shared = Service()
var allPlayers = [Player]()
var allSelectedItems = [String]()
}
I hope I did the formatting right... this is my first post on here, be gentle^^;.

Answer 1

The problem is that when you go back the old player is gone because you don't keep it , you can try to create a singleton for that
class Service {
static let shared = Service()
var allPlayers = [Player]()
var allSelectedItems = [String]()
}
// keep it here
if let cell = sender as? UITableViewCell, let vc = segue.destination as? AddPlayerViewController{
vc.managedContext = resultsController.managedObjectContext
if let indexPath = tableView.indexPath(for: cell){
let player = resultsController.object(at: indexPath)
Service.shared.allPlayers.append(player) // add this line
vc.player = player
}
}
Do same logic to append selected items and when you reach final tableView access them with
Service.shared.allPlayers
Or
Service.shared.selectedItems
That way you have a persisted container for all the selected players & items accessible anyWhere inside the app