Counter label in UITableView Cell repeats while scrolling down - ios

Question

I have counting labels in a tableview cells according to plus and minus button the label value increases and decrease count by one and when i am scrolling down the label is repeating on other cells and data is changing in cells from moving up and down.Anyone please help me with this.Thanks
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell:CustomTableViewCell = self.customTableView.dequeueReusableCell(withIdentifier: cellReuseIdentifier) as! CustomTableViewCell
cell.plusButton.tag = indexPath.row
cell.plusButton.addTarget(self, action: #selector(BtnPlusPressed(_:)), for: .touchUpInside)
cell.minusButton.tag = indexPath.row
cell.minusButton.addTarget(self, action: #selector(BtnMinusPressed(_:)), for: .touchUpInside)
cell.deviceLabel.text = self.laptop[indexPath.row]
return cell
}
#objc func BtnPlusPressed(_ sender: AnyObject) {
let button = sender as? UIButton
let cell = button?.superview?.superview as? CustomTableViewCell
let indexPath = customTableView.indexPath(for: cell!)
if let text = cell?.countLabel.text, let value = Int(text) {
var counter = value {
didSet {
cell?.countLabel.text = "\(counter)"
print()
}
}
counter += 1
callback?(counter)
}
}
#objc func BtnMinusPressed(_ sender: AnyObject) {
let button = sender as? UIButton
let cell = button?.superview?.superview as? CustomTableViewCell
let indexPath = customTableView.indexPath(for: cell!)
if let text = cell?.countLabel.text, let value = Int(text), value > 0 {
var counter = value {
didSet {
cell?.countLabel.text = "\(counter)"
}
}
counter -= 1
callback?(counter)
}
screenshot

Answer 1

I honestly don't know what's callback?(counter) doing. But I think your problem could be solved, as other people has already said, by storing your counter values along with the datasource. Right now your counterproperty only exists in the cellForRowblock.
Let's say you want all the values start from zero, and your model array is called list. You could do the following:
var counters = [Int]()
for i in 0..<list.count {
counters.append(0)
}
and then your method could be like this. I unwrapped the button to avoid dealing with optionals:
#objc func BtnMinusPressed(_ sender: AnyObject) {
guard let button = sender as? UIButton else { return }
let position = button.tag
guard counters[position] > 0 else { return }
counters[position]
counters[position] -= 1
cell.countLabel.text = "\(counters[position])"
}

Answer 2

Cells are reused. You have to save the counter value for each cell. But rather than using an extra array use a custom struct as data model
struct Model {
let name : String
var counter = 0
}
Declare the data source array
var laptop = [Model]()
And in Swift a better way as target/action is using a callback. The callback must be declared in the table view cell.
In the custom cell add IBactions and the callback to be able to update the model in the controller. The outlets for the buttons are not needed. Connect the actions to the buttons in Interface Builder.
class CustomTableViewCell: UITableViewCell {
#IBOutlet weak var deviceLabel: UILabel!
#IBOutlet weak var countLabel: UILabel!
var callback : ((Int) -> Void)?
var counter = 0 {
didSet { countLabel.text = "\(counter)" }
}
#IBAction func plusAction(_ sender: UIButton) {
counter += 1
callback?(counter)
}
#IBAction func minusAction(_ sender: UIButton) {
if counter > 0 { counter -= 1 }
callback?(counter)
}
}
In cellForRow assign the string value to the deviceLabel and assign also the callback. Whenever one of the buttons is pressed the label and the model are updated.
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = self.customTableView.dequeueReusableCell(withIdentifier: cellReuseIdentifier) as! CustomTableViewCell
let item = self.laptop[indexPath.row]
cell.deviceLabel.text = item.name
cell.counter = item.counter
cell.callback = ( newValue in
self.laptop[indexPath.row].counter = newValue
}
return cell
}
Delete also both Btn...Pressed actions. the benefit is no view hierarchy math, no tags, no objective-c-ish target/action