Turn an accessory button into a different accessory after a tap from UITableView

Question

UITableView allows you to assign an accessory -- like a button -- that shows on the right side of the cell (documentation).

In my audio app, I will want to allow a user to download by clicking the accessory and then show it succeeded with a checkmark. To test this now, I just want the accessory detail to turn into a checkmark after it's tapped.

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)

    cell.textLabel?.text = TableData[indexPath.row]

// this works, adds a button to right cell 
    cell.accessoryType = .detailDisclosureButton

    return cell
}

override func tableView(_ tableView: UITableView, accessoryButtonTappedForRowWith indexPath: IndexPath) {
    // doSomethingWithItem(indexPath.row)

   // my logic: this function applies when button is tapped. I try to reset the accessory type to checkmark when clicked 
    let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)

    cell.accessoryType = .checkmark

}

This will build, but it results in a failure starting with *** Assertion failure in -[UITableView _dequeueReusableCellWithIdentifier:forIndexPath:usingPresentationValues:],

I'm new to Swift, but this seemed logical: set a function to take an action when the accessory is clicked and then set the accessory to a checkmark (one of the accessory types).

Is there a better way to do this?

A note: I do not want to use a segue or move to a different VC; I'd like this to update the UI within the table view.

https://stackoverflow.com/questions/12737860/assertion-failure-in-dequeuereusablecellwithidentifierforindexpath — Amit, Jan 20 '18 at 06:36

Kayla Galway · Accepted Answer · 2018-01-20T06:55:33.647

Instead of using dequeReusableCell you should be using cellForRow in your accessoryButtonTappedForRow function.

Read the documentation to see the difference between those two functions and look a little further into how cell reuse works. cellForRow(at:) returns the specific UITableViewCell, which is what you are looking for in this situation.

override func tableView(_ tableView: UITableView, accessoryButtonTappedForRowWith indexPath: IndexPath) {
  // doSomethingWithItem(indexPath.row)

  // cellForRow instead of dequeue
  let cell = tableView.cellForRow(at: indexPath)

  cell.accessoryType = .checkmark

}

In addition, make sure you are registering your cell with that same reuse identifier of "cell" with either registerClass or registerNib

Thank you, Kayla. If you want to update your answer, the modification I used: `let cell = tableView.cellForRow(at: indexPath)` and it runs! — darkginger, Jan 20 '18 at 06:49

Turn an accessory button into a different accessory after a tap from UITableView

1 Answers1