fatal error: Index out of range on second cell deletion - ios

Question

In my custom cell I have a timer. When the count down reach 0, I call my delegate method and the cell is automatically deleted.
The problem is that when the second cell reach 0, my app crashes with the error fatal error: Index out of range.
In my custom cell I setup my data:
protocol MyDelegateName {
func removeOfferExpired(offerId: String, indexPath: IndexPath)
}
class MyCustomCell: UITableViewCell {
var offer:Offers?
var cellIndexPath:IndexPath?
var delegate:MyDelegateName?
func setupData(offer:Offers, indexPath:IndexPath){
self.offer = offer
self.cellIndexPath = indexPath
//...other code not relevant
}
//When the time reach zero I call the following method
func updateTime() {
if timeLeft > 0 {
timeLeft = endTime.timeIntervalSinceNow
offerExpiresLabel.textColor = UIColor.white
offerExpiresLabel.text = timeLeft.hmmss
}else {
offerExpiresLabel.textColor = UIColor.red
offerExpiresLabel.text = "Offer Expired"
timer.invalidate()
self.delegate?.removeOfferExpired(offerId: (self.offer?.offer_id!)!, indexPath: self.cellIndexPath!)
}
}
In my ViewController I setup my cell data inside cellForRowAt:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let offer = offers[indexPath.row]
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as! MyCustomCell
cell.setupData(offer: offer, indexPath: indexPath)
cell.delegate = self
return cell
}
Then inside func removeOfferExpired(offerId: String, indexPath: IndexPath) I have tried to use:
1. self.offers.remove(at: indexPath.row)
self.tableView.reloadData()
2. self.offers.remove(at: indexPath.row)
self.tableView.deleteRows(at: [indexPath], with: .automatic)
self.tableView.reloadData()
3. //and even try to "wrap" it inside begin/end updates
tableView.beginUpdates()
self.offers.remove(at: indexPath.row)
self.tableView.deleteRows(at: [indexPath], with: .automatic)
tableView.endUpdates()
it always crashes the second times. I understand that the indexPath I assign to the cell in setupData is not the same after the first cell is deleted but I thought reloadData was the way to go to update the indexPath in the remaining cells.

Answer 1

Your primary issue is that fact that you tell a cell its index path and your cell then passes that index path to its delegate. But a cell's index path isn't stable. It changes as other rows are added, removed, or moved.
The method of your cell protocol should pass itself (the cell) as a parameter, not an index path. Then the delegate can query the table view to find the cell's up-to-date index path and perform the row deletion based on that up-to-date index path.

Answer 2

As rmaddy said, what I was doing it was completely wrong. This is what I did based on his answer:
func updateTime() {
if timeLeft > 0 {
timeLeft = endTime.timeIntervalSinceNow
offerExpiresLabel.textColor = UIColor.white
offerExpiresLabel.text = timeLeft.hmmss
}else {
offerExpiresLabel.textColor = UIColor.red
offerExpiresLabel.text = "Offer Expired"
timer.invalidate()
// when the time reach zero I passed self to the delegate instead of the indexPath
self.delegate?.removeOfferExpired(offerId: (self.offer?.offer_id!)!, cell: self as UITableViewCell)
}
}
protocol MyDelegateName {
func removeOfferExpired(offerId: String, cell: UITableViewCell) // delegate method now passes the cell instead of the index
}
func removeOfferExpired(offerId: String, cell: UITableViewCell) {
// and then I get the index path from the cell
let indexPath = tableView.indexPath(for: cell)
self.offers.remove(at: (indexPath?.row)!)
self.tableView.deleteRows(at: [indexPath!], with: .automatic)
}