ios - Swift unrecognized selector sent to instance error

Question

I recently converted my project from Objective-C to Swift and in doing so I acquired this error whenever I click a button in the table view's cell. I have multiple cells being filled with information from a mysql server. I have two buttons, a follow button and followed button, when one is clicked the other is supposed to show. I've been working on this for a while but I've been stuck on this error.

Error I'm getting when I click the button in the tableview

CustomCellSwift[1425:372289] -[CustomCellSwift.ViewController followButtonClick:]: unrecognized selector sent to instance 0x100b13a40

In CustomCell.swift

class CustomCell: UITableViewCell {

@IBOutlet weak var firstStatusLabel: UILabel!
@IBOutlet weak var secondStatusLabel: UILabel!
@IBOutlet weak var myImageView: UIImageView!
@IBOutlet weak var followButton: UIButton!
@IBOutlet weak var followedButton: UIButton!

override func awakeFromNib() {
    super.awakeFromNib()

    self.followButton.isHidden = true
    self.followedButton.isHidden = true
}

override func setSelected(_ selected: Bool, animated: Bool) {
    super.setSelected(selected, animated: animated)
}

func populateCell(_ testObject: Test, isFollowed: Bool, indexPath: IndexPath, parentView: Any) {

    // Loading Background Color
    self.backgroundColor = UIColor.white

    // Loading Status Labels
    self.firstStatusLabel.text = testObject.testStatus1
    self.secondStatusLabel.text = testObject.testStatus2
    self.firstStatusLabel.isHidden = true
    self.secondStatusLabel.isHidden = true

    if isFollowed {
        self.followedButton.tag = indexPath.row
        self.followedButton.addTarget(parentView, action: Selector(("followedButtonClick")), for: .touchUpInside)
        self.followedButton.isHidden = false
        self.followButton.isHidden = true

        // Status Labels
        self.firstStatusLabel.isHidden = false
        self.secondStatusLabel.isHidden = false

    }
    else {
        self.followButton.tag = indexPath.row
        self.followButton.addTarget(parentView, action: Selector(("followButtonClick:")), for: .touchUpInside)
        self.followedButton.isHidden = true
        self.followButton.isHidden = false

        // Status Labels
        self.firstStatusLabel.isHidden = false // True when done testing
        self.secondStatusLabel.isHidden = false // True when done testing

    }
  }
}

ViewController.swift

CellForRowAt indexPath

public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let CellIdentifier = "Cell"
    var cell = tableView.dequeueReusableCell(withIdentifier: CellIdentifier) as! CustomCell

    if cell != cell {
        cell = CustomCell(style: UITableViewCellStyle.default, reuseIdentifier: CellIdentifier)
    }

    // Coloring TableView
    myTableView.backgroundColor = UIColor.white

    // Configuring the cell
    var testObject: Test

    if !isFiltered {
        if indexPath.section == 0 {
            testObject = followedArray[indexPath.row] 
            cell.populateCell(testObject, isFollowed: true, indexPath: indexPath, parentView: self)
        }
        else if indexPath.section == 1 {
            testObject = testArray[indexPath.row] 
            cell.populateCell(testObject, isFollowed: false, indexPath: indexPath, parentView: self)
        }
    }
    else {
        testObject = filteredArray[indexPath.row] as! Test
        cell.populateCell(testObject, isFollowed: false, indexPath: indexPath, parentView: self)
    }

    return cell
}

Follow Button Code

@IBAction func followButtonClick(sender: UIButton!) {

    // Adding row to tag
    let buttonPosition = (sender as AnyObject).convert(CGPoint.zero, to: self.myTableView)
    if let indexPath = self.myTableView.indexPathForRow(at: buttonPosition) {

        // Showing Status Labels
        let cell = self.myTableView.cellForRow(at: indexPath) as! CustomCell
        cell.firstStatusLabel.isHidden = false
        cell.secondStatusLabel.isHidden = false

        // Change Follow to Following
        (sender as UIButton).setImage(UIImage(named: "follow.png")!, for: .normal)
        cell.followButton.isHidden = true
        cell.followedButton.isHidden = false
        self.myTableView.beginUpdates()

        // ----- Inserting Cell to Section 0 -----
        followedArray.insert(testArray[indexPath.row], at: 0)
        myTableView.insertRows(at: [IndexPath(row: 0, section: 0)], with: .fade)

        // ----- Removing Cell from Section 1 -----
        testArray.remove(at: indexPath.row)
        let rowToRemove = indexPath.row
        self.myTableView.deleteRows(at: [IndexPath(row: rowToRemove, section: 1)], with: .fade)

        self.myTableView.endUpdates()

    }
}

Unfollow button code is the same as the follow button.

I think the problem is in CustomCell.swift in the button selector(("")) but the error is saying -[CustomCellSwift.ViewController followButtonClick:] which means in ViewController in the follow button code but I don't know what to do anymore.

Answer 1

Two changes for Swift 3:

The selector should look like:

#selector(ClassName.followButtonClick(_:))

The function should have an underscore:

@IBAction func followButtonClick(_ sender: UIButton!) { ...

Notice that these two should be in the same class, otherwise, make sure you initialize the ClassName class.

If you want the selector method(followButtonClick(_:)) to be in the UITableViewCell class. Remove @IBAction(I don't think you need it there):

func followButtonClick(_ sender: UIButton!) { ...