如何通过选择器Swift 3传递变量以起作用

Question

I'm trying to pass a variable to a function which is called within a selector but I'm getting the error 'Argument of #selector does not refer to an @objc method' how am I supposed to pass a variable to a function in a selector.

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "compCell", for: indexPath) as! CompCell


    // creating the cell
    cell.postImage.downloadImage(from: self.winners[indexPath.row].pathToImage)
    print(self.winners[indexPath.row].votes)
    let num = self.winners[indexPath.row].votes!

    cell.votesLabel.text = "\(num) votes"
    cell.title.text = self.winners[indexPath.row].title
    cell.postID = self.winners[indexPath.row].postID
    cell.compID = self.winners[indexPath.row].compID
    //tempComp = cell


    let tap = UIGestureRecognizer(target: self, action: #selector(caller(_pressed: cell)))
    cell.isUserInteractionEnabled = true
    cell.addGestureRecognizer(tap)


    return cell
}


func caller(_pressed: CompCell) {
      isPressed(_pressedCell: _pressed)
}

func isPressed(_pressedCell: CompCell) {
    self.selectedComp = _pressedCell
    //prepare(for: IndividualCompSegue, sender: <#T##Any?#>)
    performSegue(withIdentifier: "IndividualCompSegue", sender: self)
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let destination = segue.destination as? IndividualCompViewController {
        destination.comp = self.selectedComp
    }
}

Answer 1

You can't pass arbitrary values with the action of a UIGestureRecognizer . An action takes one parameter which is the UIGestureRecognizer which triggers the action.

In your case, you can get the cell which triggered the tap with the view property of the gesture recognizer.

func tapHandler(_ recognizer: UITapGestureRecognizer) {
    if let cell = recognizer.view as? Compcell {
        isPressed(_pressedCell: cell)
    }
}

Also, if you want to detect taps, you need to create a UITapGestureRecognizer :

let tap = UITapGestureRecognizer(target: self, action: #selector(tapHandler))

---

Instead of using a tap gesture recognizer to detect a selected cell, you can use

override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    let cell = self.collectionView(collectionView, cellForItemAt: indexPath) as! CompCell
    isPressed(_pressedCell: cell)      
}