Nothing Happens When UITableView is Clicked (trying to send data between views) - swift

Question

So I have a two page app. The purpose of the app being the user can store expenses. They log a name and amount (attributes) and this data is stored in Expenses (entity). I have figured out how to create core data values, delete and retrieve. I am now working on updating. This will work by the user tapping on a table in the first view (ExpensesViewController) where the expenses are stored and this takes them to the 2nd view (EditExpensesViewController) where they can update the value back into core data. I am stuck on this 'data transfer' between the views.
I am using the storyboard and connected the first view to the second via 'show' set the segue identifier as 'editExpense'. However nothing happens when the table row is tapped. Any idea why it's not working and what I may have missed out? See here for GIF
ExpensesViewController
import UIKit
import CoreData
class ExpensesViewController: UIViewController {
#IBOutlet weak var totalLabel: UILabel!
#IBOutlet weak var tableView: UITableView!
var expenses_array = [Expenses]()
var send_array = [Expenses]()
override func viewDidLoad(){
super.viewDidLoad()
retrieveExpenses()
}
func retrieveExpenses(){
let fetchRequest: NSFetchRequest<Expenses> = Expenses.fetchRequest()
do {
let expenses = try PersistenceService.context.fetch(fetchRequest)
self.expenses_array = expenses
self.tableView.reloadData()
} catch {
print(error.localizedDescription )
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "editExpense") {
let secondViewController = segue.destination as! EditExpensesViewController
secondViewController.send_array = send_array
}
}
}
extension ExpensesViewController: UITableViewDataSource {
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return expenses_array.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: .value1, reuseIdentifier: nil)
cell.textLabel?.text = expenses_array[indexPath.row].name
cell.detailTextLabel?.text = expenses_array[indexPath.row].amount
return cell
}
func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
return true
}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
if (editingStyle == .delete) {
let fetchRequest: NSFetchRequest<Expenses> = Expenses.fetchRequest()
do {
let result = try PersistenceService.context.fetch(fetchRequest)
// Delete from Core Data and remove from the arrays then save
if result.contains(expenses_array[indexPath.row]){
PersistenceService.context.delete(expenses_array[indexPath.row])
expenses_array = expenses_array.filter { $0 != expenses_array[indexPath.row] }
PersistenceService.saveContext()
self.getTotalExpenses()
self.tableView.reloadData()
}
} catch {
print(error.localizedDescription )
}
}
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
send_array = [self.expenses_array[indexPath.row]]
self.performSegue(withIdentifier: "editExpense", sender: self)
}
}
EditExpensesViewController
import UIKit
import CoreData
class EditExpensesViewController: UIViewController {
var send_array = [Expenses]() // Defined from the previous view controller
override func viewDidLoad() {
super.viewDidLoad()
print(send_array)
}
}

Answer 1

First of all conform to tableView delegates and dataSource in your viewDidLoad() :
tableView.delegate = self
tableView.dataSource = self
Delete segue from stroyboard and we will present the controller in code using :
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "editExpense") {
let secondViewController = segue.destination as! EditExpensesViewController
secondViewController.send_array = send_array
// "someIdentifier" is the identifier of secondController in storyboard
storyboard?.instantiateViewController(withIdentifier: "someIdentifier")
present(secondViewController, animated: true, completion: nil)
}
}
Be aware to put storyboard identifier for second controller in storyboard using attribute inspector

Answer 2

The problem is that your first view controller is the UITableViewDataSource only. That is not enough. It needs to be the UITableViewDelegate too. didSelectRowAt Is a delegate method, not a data source method, and will not be called unless this view controller is the table views delegate and is explicitly declared as conforming to UITableViewDelegate.