cellForRowAt in TableView not updating - ios

Question

I have a table view controller that displays names of shopping lists. These shopping lists are created through a shopping list class, which lets me specify the name of the shopping list and items in it. This table view displays around 5 shopping lists (names). When I press one, I go to another table view controller, which shows the items of the shopping list. However, when I go back to the shopping list (names) table view controller and press another shopping list, it still displays the items from the old shopping list and not the one that was pressed. I think I have narrowed the problem down to the cellForItemAt of the second table view controller not being called again.
import UIKit
class List: NSObject {
var name: String
var items: [String?]
var shared: String?
init(name: String, items: [String], shared: String?) {
self.name = name
self.items = items
self.shared = shared
}
}
enum ListType {
case apply
case view
}
class ListViewController: UITableViewController {
//Initialize Variables Here
let cellId = "cellId"
var lists: [List] = [
List(name: "Veggies", items: ["Fruit Loops", "Pasta"], shared: nil),
List(name: "11/17/18", items: ["Eggs", "Green Beans", "Pirate Booty", "Bread", "Milk"], shared: nil),
List(name: "Fruits", items: ["Fruit Loops", "Oranges"], shared: nil),
List(name: "Red Foods", items: ["Apples", "Tomatoes", "Watermelon", "Cherries"], shared: nil),
List(name: "Grains", items: ["Bread Crumbs", "Pasta", "Rice", "Chicken Flavored Rice"], shared: nil)
]
//Create Class Lazy Vars
lazy var newListVC: NewListViewController = {
let launcher = NewListViewController()
// launcher.homeController = self
return launcher
}()
lazy var listItemsVC: ListItemsViewController = {
let launcher = ListItemsViewController()
// launcher.homeController = self
return launcher
}()
//Setup Enums and Switches
var listType: ListType!
override func viewDidLoad() {
super.viewDidLoad()
//Things that both cases have in common:
navigationController?.navigationBar.prefersLargeTitles = true
let addBarButtonItem = UIBarButtonItem(title: "+", style: .plain, target: self, action: #selector(newList)) //+ Button
addBarButtonItem.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 27)!], for: .normal)
addBarButtonItem.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 27)!], for: .selected)
//SWITCH STATEMENT
switch listType as ListType {
case ListType.apply:
//Apply Begin
navigationItem.title = "Apply List"
//Setup Navigation Bar Items
let locateBarButtonItem = UIBarButtonItem(title: "Locate Item", style: .plain, target: self, action: nil)
//Add items to navigation bar
navigationItem.rightBarButtonItems = [addBarButtonItem, locateBarButtonItem]
//Apply End
case ListType.view:
//View Begin
//Setup Navigation Bar
navigationItem.title = "My Lists"
//Add items to navigation bar
navigationItem.rightBarButtonItem = addBarButtonItem
navigationItem.leftBarButtonItem = editButtonItem
//View End
}
//SWITCH STATEMENT END
//Register TableView with Id: cellId
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
}
#objc func newList() {
newListVC.pageControlFunc(pageView: PageView.name)
navigationController?.pushViewController(newListVC, animated: true) //Then pushes listVC
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return lists.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)
cell.textLabel?.text = self.lists[indexPath.row].name //Then sets cell of indexPath text = lists value of index path
return cell
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
listItemsVC.listName = lists[indexPath.row].name
listItemsVC.listItems = lists[indexPath.row].items
print(listItemsVC.listItems)
navigationController?.pushViewController(listItemsVC, animated: true)
}
}
///////////////////////////////////////////////////////////////////////////
SECOND UITABLEVIEW - NOT UPDATING
///////////////////////////////////////////////////////////////////////////
import UIKit
class ListItemsViewController: UITableViewController {
//Initialize Variables Here
let cellId = "cellId1"
var listName: String?
var listItems: [String?] = []
override func viewDidLoad() {
super.viewDidLoad()
//Things that both cases have in common:
navigationController?.navigationBar.prefersLargeTitles = true
//Set Title
navigationItem.title = listName
//Register TableView with Id: cellId
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
//Delegate method not called on push to view
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return listItems.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)
cell.textLabel?.text = listItems[indexPath.row] //Then sets cell of indexPath text = lists value of index path
return cell
}
}
Thanks in advance!

Answer 1

ViewDidLoadis called once, when the ViewController is first loaded into memory. Since your ListsItemsViewController is a strong property on your ListViewController, and you are navigating to it multiple times, nothing is ever telling it to update its views or reload your tableview because it does not get deallocated(so ViewDidLoad and the TableView delegate/datasource methods do not get called). You also haven't added any custom code telling it to update.
If you want to keep those view controllers as class properties of ListViewController, then you can add tableView.reloadData in the ViewWillAppear method of ListsItemsViewController as shown below.
import UIKit
class List: NSObject {
var name: String
var items: [String?]
var shared: String?
init(name: String, items: [String], shared: String?) {
self.name = name
self.items = items
self.shared = shared
}
}
enum ListType {
case apply
case view
}
class ListViewController: UITableViewController {
//Initialize Variables Here
let cellId = "cellId"
var lists: [List] = [
List(name: "Veggies", items: ["Fruit Loops", "Pasta"], shared: nil),
List(name: "11/17/18", items: ["Eggs", "Green Beans", "Pirate Booty", "Bread", "Milk"], shared: nil),
List(name: "Fruits", items: ["Fruit Loops", "Oranges"], shared: nil),
List(name: "Red Foods", items: ["Apples", "Tomatoes", "Watermelon", "Cherries"], shared: nil),
List(name: "Grains", items: ["Bread Crumbs", "Pasta", "Rice", "Chicken Flavored Rice"], shared: nil)
]
//Create Class Lazy Vars
lazy var newListVC: NewListViewController = {
let launcher = NewListViewController()
// launcher.homeController = self
return launcher
}()
lazy var listItemsVC: ListItemsViewController = {
let launcher = ListItemsViewController()
// launcher.homeController = self
return launcher
}()
//Setup Enums and Switches
var listType: ListType!
override func viewDidLoad() {
super.viewDidLoad()
//Things that both cases have in common:
navigationController?.navigationBar.prefersLargeTitles = true
let addBarButtonItem = UIBarButtonItem(title: "+", style: .plain, target: self, action: #selector(newList)) //+ Button
addBarButtonItem.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 27)!], for: .normal)
addBarButtonItem.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 27)!], for: .selected)
//SWITCH STATEMENT
switch listType as ListType {
case ListType.apply:
//Apply Begin
navigationItem.title = "Apply List"
//Setup Navigation Bar Items
let locateBarButtonItem = UIBarButtonItem(title: "Locate Item", style: .plain, target: self, action: nil)
//Add items to navigation bar
navigationItem.rightBarButtonItems = [addBarButtonItem, locateBarButtonItem]
//Apply End
case ListType.view:
//View Begin
//Setup Navigation Bar
navigationItem.title = "My Lists"
//Add items to navigation bar
navigationItem.rightBarButtonItem = addBarButtonItem
navigationItem.leftBarButtonItem = editButtonItem
//View End
}
//SWITCH STATEMENT END
//Register TableView with Id: cellId
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
}
#objc func newList() {
newListVC.pageControlFunc(pageView: PageView.name)
navigationController?.pushViewController(newListVC, animated: true) //Then pushes listVC
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return lists.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)
cell.textLabel?.text = self.lists[indexPath.row].name //Then sets cell of indexPath text = lists value of index path
return cell
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
listItemsVC.listName = lists[indexPath.row].name
listItemsVC.listItems = lists[indexPath.row].items
print(listItemsVC.listItems)
navigationController?.pushViewController(listItemsVC, animated: true)
}
}
///////////////////////////////////////////////////////////////////////////
SECOND UITABLEVIEW - NOT UPDATING
///////////////////////////////////////////////////////////////////////////
import UIKit
class ListItemsViewController: UITableViewController {
//Initialize Variables Here
let cellId = "cellId1"
var listName: String?
var listItems: [String?] = []
override func viewDidLoad() {
super.viewDidLoad()
//Things that both cases have in common:
navigationController?.navigationBar.prefersLargeTitles = true
//Set Title
navigationItem.title = listName
//Register TableView with Id: cellId
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
//Delegate method not called on push to view
}
//This will always get called when this view controller's view is added to the window
//so you can guarantee it will call your delegate methods to reload the tableView with your new data
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated: animated)
tableView.reloadData()
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return listItems.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)
cell.textLabel?.text = listItems[indexPath.row] //Then sets cell of indexPath text = lists value of index path
return cell
}
}
The other option would be removing those lazy vars and just initializing those view controllers as needed, so that they get deallocated once you remove them from the stack. This would mean that your tableviews would always reload without having to add any code in ViewWillAppear
import UIKit
class List: NSObject {
var name: String
var items: [String?]
var shared: String?
init(name: String, items: [String], shared: String?) {
self.name = name
self.items = items
self.shared = shared
}
}
enum ListType {
case apply
case view
}
class ListViewController: UITableViewController {
//Initialize Variables Here
let cellId = "cellId"
var lists: [List] = [
List(name: "Veggies", items: ["Fruit Loops", "Pasta"], shared: nil),
List(name: "11/17/18", items: ["Eggs", "Green Beans", "Pirate Booty", "Bread", "Milk"], shared: nil),
List(name: "Fruits", items: ["Fruit Loops", "Oranges"], shared: nil),
List(name: "Red Foods", items: ["Apples", "Tomatoes", "Watermelon", "Cherries"], shared: nil),
List(name: "Grains", items: ["Bread Crumbs", "Pasta", "Rice", "Chicken Flavored Rice"], shared: nil)
]
//Setup Enums and Switches
var listType: ListType!
override func viewDidLoad() {
super.viewDidLoad()
//Things that both cases have in common:
navigationController?.navigationBar.prefersLargeTitles = true
let addBarButtonItem = UIBarButtonItem(title: "+", style: .plain, target: self, action: #selector(newList)) //+ Button
addBarButtonItem.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 27)!], for: .normal)
addBarButtonItem.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 27)!], for: .selected)
//SWITCH STATEMENT
switch listType as ListType {
case ListType.apply:
//Apply Begin
navigationItem.title = "Apply List"
//Setup Navigation Bar Items
let locateBarButtonItem = UIBarButtonItem(title: "Locate Item", style: .plain, target: self, action: nil)
//Add items to navigation bar
navigationItem.rightBarButtonItems = [addBarButtonItem, locateBarButtonItem]
//Apply End
case ListType.view:
//View Begin
//Setup Navigation Bar
navigationItem.title = "My Lists"
//Add items to navigation bar
navigationItem.rightBarButtonItem = addBarButtonItem
navigationItem.leftBarButtonItem = editButtonItem
//View End
}
//SWITCH STATEMENT END
//Register TableView with Id: cellId
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
}
#objc func newList() {
let newListVC = NewListViewController()
newListVC.pageControlFunc(pageView: PageView.name)
navigationController?.pushViewController(newListVC, animated: true) //Then pushes listVC
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return lists.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)
cell.textLabel?.text = self.lists[indexPath.row].name //Then sets cell of indexPath text = lists value of index path
return cell
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let listItemsVC = ListItemsViewController()
listItemsVC.listName = lists[indexPath.row].name
listItemsVC.listItems = lists[indexPath.row].items
print(listItemsVC.listItems)
navigationController?.pushViewController(listItemsVC, animated: true)
}
}
///////////////////////////////////////////////////////////////////////////
SECOND UITABLEVIEW - NOT UPDATING
///////////////////////////////////////////////////////////////////////////
import UIKit
class ListItemsViewController: UITableViewController {
//Initialize Variables Here
let cellId = "cellId1"
var listName: String?
var listItems: [String?] = []
override func viewDidLoad() {
super.viewDidLoad()
//Things that both cases have in common:
navigationController?.navigationBar.prefersLargeTitles = true
//Set Title
navigationItem.title = listName
//Register TableView with Id: cellId
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
//Delegate method not called on push to view
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return listItems.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)
cell.textLabel?.text = listItems[indexPath.row] //Then sets cell of indexPath text = lists value of index path
return cell
}
}