How to inject presenter to CustomTableViewCell as dependancy injection - swift

Question

i'm learning Dependency Injection and created an app by MVP.
I could inject presenters for a few VCs in AppDelegate using storyboard.
But now I created CustomTableViewCell with .xib that has UIButton on the cell so that I would like to process the detail of it in the presenter file.
I tried to create UINib(nibName~ in AppDelegate but when the presenter in CustomTableViewCell is called, it is nil.
I heard that an instance of a cell called in 'AppDelegate' is going to be disposed of. However I don't know any ways not to make presenter nil.
AppDelegate
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
let mainTabVC = UIStoryboard(name: "MainTab", bundle: nil).instantiateInitialViewController() as! MainTabViewController
let userDefault = UserDefault()
let presenter = MainTabPresenter(view: mainTabVC, udManager: userDefault)
mainTabVC.inject(presenter: presenter, userDefaultManager: userDefault)
let addTabVC = UIStoryboard(name: "AddTab", bundle: nil).instantiateInitialViewController() as! AddTabViewController
let alertHandller = AlertHandller()
let addPresenter = AddTabPresenter(view: addTabVC, mainView: mainTabVC, alertHandller: alertHandller)
addTabVC.inject(presenter: addPresenter)
let settingTabVC = UIStoryboard(name: "SettingTab", bundle: nil).instantiateInitialViewController() as! SettingTabViewController
let settingPresenter = SettingTabPresenter(view: settingTabVC)
settingTabVC.inject(presenter: settingPresenter, alertHandller: alertHandller)
let vcs = [mainTabVC, addTabVC, settingTabVC]
let mainTabBar = UIStoryboard(name: "MainView", bundle: nil).instantiateInitialViewController() as! MainTabBarController
mainTabBar.setViewControllers(vcs, animated: false)
// no probs until here (inject functions work)
// this is disposed??
let listCell = UINib(nibName: "ListCell", bundle: nil).instantiate(withOwner: ListCell.self, options: nil).first as! ListCell
let cellPresenter = ListCellPresenter(view: mainTabVC)
listCell.inject(presenter: cellPresenter)
window = UIWindow(frame: UIScreen.main.bounds)
window?.rootViewController = mainTabBar
window?.makeKeyAndVisible()
return true
}
VC that tableViewDataSource is written
class MainTabViewController: UIViewController {
private let shared = Sharing.shared
private var presenter: MainTabPresenterInput!
private var userDefaultManager: UserDefaultManager!
func inject(presenter: MainTabPresenterInput, userDefaultManager: UserDefaultManager) {
self.presenter = presenter
self.userDefaultManager = userDefaultManager
}
override func viewDidLoad() {
super.viewDidLoad()
tableViewSetup()
}
func tableViewSetup(){
tableView.delegate = self
tableView.dataSource = self
tableView.register(UINib(nibName: "ListCell", bundle: nil), forCellReuseIdentifier: "ListCell")
}
}
extension MainTabViewController: UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return shared.items.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ListCell") as! ListCell
if let item = presenter.item(row: indexPath.row) {
cell.configure(item: item)
}
return cell
}
}
customTableViewCell
class ListCell: UITableViewCell {
private let shared = Sharing.shared
private var presenter: ListCellPresenterInput!
func inject(presenter: ListCellPresenterInput) {
self.presenter = presenter
}
override func awakeFromNib() {
super.awakeFromNib()
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
#IBAction func favButtonTapped(_ sender: Any) {
let row = self.tag
switch shared.items[row].fav {
case true:
favButton.setImage(UIImage(named: "favIconNon"), for: .normal)
case false:
favButton.setImage(UIImage(named: "favIcon"), for: .normal)
}
presenter.countFavIcon(rowAt: row)　// this presenter is nil
}
func configure(item: Item) {
　　　　・・・
}
}
cell presenter
protocol AddTabPresenterInput {
func addButtonTapped(item item: Item?)
}
protocol AddTabPresenterOutput: AnyObject {
func clearFields()
func showAlert(alert: UIAlertController)
}
final class AddTabPresenter: AddTabPresenterInput {
private weak var view: AddTabPresenterOutput!
private weak var mainView: MainTabPresenterOutput!
private weak var alertHandller: AlertHandllerProtocol!
let shared = Sharing.shared
init(view: AddTabPresenterOutput, mainView: MainTabPresenterOutput, alertHandller: AlertHandllerProtocol) {
self.view = view
self.mainView = mainView
self.alertHandller = alertHandller
}
func addButtonTapped(item item: Item?) {
print("called")
mainView.updateView()
}
}
How Can I solve the issue that presenter is nil?
Hopefully some of you would help me out.
Thank you.

Answer 1

UITableView uses reusable cells, you can find a lot of info in google, here is one of the articles
https://medium.com/ios-seminar/why-we-use-dequeuereusablecellwithidentifier-ce7fd97cde8e
So creating an instance of UITableViewCell in AppDelegate you're doing nothing, it is immediately dispose
Create presenter
// somewhere in your MainTabViewController
let cellPresenter = ListCellPresenter(view: self)
To inject presenter you should use tableView(_:cellForRowAt:) method
// later in code
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ListCell") as! ListCell
cell.inject(presenter: cellPresenter)
if let item = presenter.item(row: indexPath.row) {
cell.configure(item: item)
}
return cell
}