Is there a simple way to delete specific custom cells from a UITableView? - ios

Question

I am trying to instantiate empty Buyer cells (custom cell) in my table view and then have the user populate the buyers' names. When the user presses the delete button for a row/cell, it should delete the corresponding row/cell regardless of whether or not the textfield for that row has been populated or not. Clearly, I am not getting the desired behavior. For example, when I press delete Row0 (whose textfield says "Buyer 0") and the tableview reloads, Buyer 0 is still there, but one of the empty Buyer cells at the end gets deleted instead.
import UIKit
class EntryAlertViewController: UIViewController {
//Fields/Table
#IBOutlet weak var itemField: UITextField!
#IBOutlet weak var priceField: UITextField!
#IBOutlet weak var tableView: UITableView!
//Visual Components
#IBOutlet weak var mainView: UIView!
#IBOutlet weak var titleView: UIView!
#IBOutlet weak var splitItemButton: UIButton!
#IBOutlet weak var cancelButton: UIButton!
#IBOutlet weak var addItemButton: UIButton!
//Commonly Used Objects/Variables
var potentialBuyers: [String] = []
override func viewDidLoad() {
super.viewDidLoad()
potentialBuyers.append("")
tableView.dataSource = self
tableView.register(UINib(nibName: "BuyerCell", bundle: nil), forCellReuseIdentifier: "ReusableCell")
}
override func viewWillAppear(_ animated: Bool) {
}
#IBAction func splitItemPressed(_ sender: UIButton) {
potentialBuyers.append("")
tableView.reloadData()
}
}
Here are the tableview datasource and the delete button delegate.
extension EntryAlertViewController: UITableViewDataSource, DeleteButtonDelegate {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return potentialBuyers.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ReusableCell", for: indexPath) as! BuyerCell
cell.deleteButtonDelegate = self
cell.indexPath = indexPath
cell.nameField.text = cell.buyerName
if potentialBuyers.count == 1 {
cell.deleteButton.isHidden = true
} else {
cell.deleteButton.isHidden = false
}
return cell
}
func deletePressed(index: Int) {
potentialBuyers.remove(at: index)
tableView.reloadData()
}
}
And here is my BuyerCell class with the UITextFieldDelegate as an extension.
import UIKit
protocol DeleteButtonDelegate {
func deletePressed(index: Int)
}
class BuyerCell: UITableViewCell {
#IBOutlet weak var deleteButton: UIButton!
#IBOutlet weak var nameField: UITextField!
var deleteButtonDelegate: DeleteButtonDelegate!
var indexPath: IndexPath!
var buyerName: String?
override func awakeFromNib() {
super.awakeFromNib()
self.nameField.delegate = self
}
#IBAction func deletePressed(_ sender: UIButton) {
//print the indexPath.row that this was pressed for
print("delet pressed for \(indexPath.row)")
self.deleteButtonDelegate?.deletePressed(index: indexPath.row)
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
}
extension BuyerCell: UITextFieldDelegate {
func textFieldDidBeginEditing(_ textField: UITextField) {
print("textFieldDidBeginEditing")
buyerName = nameField.text
}
func textFieldDidEndEditing(_ textField: UITextField) {
print("textFieldDidEndEditing")
buyerName = nameField.text
}
}

Answer 1

Your problem is in this line
cell.nameField.text = cell.buyerName
Cells are reused from a reuse pool, so you can't rely on the cell holding any particular state or value.
Your buyer name needs to come from your data model array.
Something like
cell.nameField.text = self.potentialBuyers[indexPath.row]
Reloading the whole tableview is a bit excessive when you have only deleted a single row; Just delete the relevant row.
You can also clean up your delegation protocol so that there is no need for the cell to track its indexPath -
protocol DeleteButtonDelegate {
func deletePressed(in cell: UITableViewCell)
}
In your cell:
#IBAction func deletePressed(_ sender: UIButton) {
self.deleteButtonDelegate?.deletePressed(in: self)
}
In your view controller:
func deletePressed(in cell: UITableViewCell) {
guard let indexPath = tableView.indexPath(for: cell) else {
return
}
potentialBuyers.remove(at: indexPath.row)
tableView.deleteRows(at:[indexPath], with: .automatic)
}

Answer 2

There is a major issue in your code. You are not updating the data model so the changes in the cells are lost when the user scrolls.
Rather then quite objective-c-ish protocol/delegate in Swift callback closures are much more convenient and efficient. You can use one callback for both updating the model and deleting the cell.
Replace the BuyerCell cell with
class BuyerCell: UITableViewCell {
#IBOutlet weak var deleteButton: UIButton!
#IBOutlet weak var nameField: UITextField!
var callback : ((UITableViewCell, String?) -> Void)?
override func awakeFromNib() {
super.awakeFromNib()
self.nameField.delegate = self
}
#IBAction func deletePressed(_ sender: UIButton) {
callback?(self, nil)
}
}
extension BuyerCell: UITextFieldDelegate {
func textFieldDidBeginEditing(_ textField: UITextField) {
print("textFieldDidBeginEditing")
callback?(self, nameField.text)
}
func textFieldDidEndEditing(_ textField: UITextField) {
print("textFieldDidEndEditing")
callback?(self, nameField.text)
}
}
In the controller in cellForRow assign the callback and handle the actions. The actions work also reliably if cells are reordered, inserted or deleted.
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ReusableCell", for: indexPath) as! BuyerCell
let buyerName = potentialBuyers[indexPath.row]
cell.nameField.text = buyerName
cell.callback = { [unowned self] cCell, cName in
let currentIndexPath = tableView.indexPath(for: cCell)!
if let name = cName {
self.potentialBuyers[currentIndexPath.row] = name
} else {
self.potentialBuyers.remove(at: currentIndexPath.row)
tableView.deleteRows(at: [currentIndexPath], with: .fade)
}
}
cell.deleteButton.isHidden = potentialBuyers.count == 1
return cell
}