Swift: UIButton within a custom UITableViewCell 'Unrecognised selector sent to instance' error

Question

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cellIdentifier = "ExerciseMenuCell"
    let cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath: indexPath) as! ExerciseOptionTableViewCell
    let currentWorkout = workouts[indexPath.row]
    cell.nameLabel!.text = currentWorkout.name
    cell.photoImageView.image = currentWorkout.filename

    cell.startWorkout.tag = indexPath.row
    cell.startWorkout.addTarget(self, action:Selector("workoutAction:"), forControlEvents: .TouchUpInside)

    cell.infoWorkout.tag = indexPath.row
    cell.infoWorkout.addTarget(self, action:Selector("infoAction:"), forControlEvents: .TouchUpInside)

    return cell
    }

Both startWorkout and infoWorkout cause the application to crash with the error message 'unrecognised selector sent to instance'.

Example of code within the button actions. I am trying to return the indexPath of the button so I can then act on that.

@IBAction func workoutAction(sender: AnyObject) {
    let buttonTag = sender.tag
    print(buttonTag)

}

exact error message:

016-06-17 18:34:30.722 Exercises[4711:245683] - [Exercises.ExerciseMenu beginWorkout:]: unrecognized selector sent to instance 0x7fb47874a4b0 2016-06-17 18:34:30.727 Exercises[4711:245683] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Exercises.ExerciseMenu beginWorkout:]: unrecognized selector sent to instance 0x7fb47874a4b0'

More info needed: 1) What is the exact message in crash log ? 2) Where did you write the workoutAction and infoAction methods ? — Midhun MP
The methods are written within the same view controller as the cellForRowAtIndexPath method. I'll edit the post to show more of the error message. — Ryan Hampton
The error shows that, the crash was happening due to beginWorkout method. So I think the crash is happening somewhere else or you edited the actual code and forgot to update the crash log! — Midhun MP
beginWorkout is the following view controller. so the error would be in the segue between them? — Ryan Hampton

brl214 brl214 · Accepted Answer · 2016-06-17T18:52:38

A button within a custom cell cannot call an action that is in the housing view controller. You need to:

1) Move the @IBaction function to the custom cell class

2) Remove the add target code from 'cellFromRowAtIndexPath' and either write that in your custom cell(if you do this you don't need to write @IBAction) or create the connection from the button in storyboard to the @IBAction function

3) Create a delegate for your custom cell Custom UITableViewCell delegate pattern in Swift

4) Call the delegate from your custom cell for the function you implement in the view controller **Don't for get you need cell.delegate = self or it will crash when the delegate gets called

ex:

CustomCell.swift

protocol CustomCellDelegate {
    func pressedButton()
}

class CustomCell: UITableViewCell {
    var delegate: CustomCellDelegate!

    @IBAction func buttonPressed(sender: UIButton) {
        delegate.pressedButton()
    }
}

ViewController.swift

class CustomClass: UIViewController, CustomCellDelegate {

    func pressedButton() {
        // Perform segue here
    }
}

Swift: UIButton within a custom UITableViewCell 'Unrecognised selector sent to instance' error

1 Answers