如何避免在任何单元格中添加多个点击手势？

Question

I have a weird problem. When scrolling down, cells disappear if Tap Gesture happened.

Looks like I need to stop adding Tap Gesture to cells. I've done testing of this condition in function but it didn't work.

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

 let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as!  ToDoItemsCell

...

        cell.textField.delegate = self
        cell.textField.isHidden = true
        cell.toDoItemLabel.isUserInteractionEnabled = true

        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(toDoItemLabelTapped))

        tapGesture.numberOfTapsRequired = 1
        cell.addGestureRecognizer(tapGesture)

        return cell
}

And here is my function:

 @objc func toDoItemLabelTapped(_ gesture: UITapGestureRecognizer) {

        if gesture.state == .ended {

            let location = gesture.location(in: self.tableView)

             if let indexPath = tableView.indexPathForRow(at: location) {

                if let cell = self.tableView.cellForRow(at: indexPath) as? ToDoItemsCell {
                cell.toDoItemLabel.isHidden = true
                cell.textField.isHidden = false
                cell.textField.becomeFirstResponder()
                cell.textField.text = cell.toDoItemLabel.text

           }
         }
       }
     }

Tapping works, but it keeps adding to other cells and makes them disappear. What can be the issue?

Answer 1

Gesture should be added once to each cell. In your code gesture will be added every time cellForRowAt will be called and it will be called many times especially when you scroll down to list.

Move you gesture add code to ToDoItemsCell class and than you can use delegates to inform your view controller when cell gets tapped.

protocol ToDoItemsCellDelegate {
    toDoItemsCellDidTapped(_ cell: ToDoItemsCell)
}

class ToDoItemsCell : UITableViewCell {
    weak var delegate: ToDoItemsCellDelegate?
    var indexPath: IndexPath!
    override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        // code common to all your cells goes here
        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(toDoItemLabelTapped))

        tapGesture.numberOfTapsRequired = 1
        self.addGestureRecognizer(tapGesture)
    }

    @objc func toDoItemLabelTapped(_ gesture: UITapGestureRecognizer) {
         delegate?.toDoItemsCellDidTapped(self)
    }
}

In function cellForRowAt you can just select the delegate and set indexPath.

Note: If you just wanted to perform action when user taps any cell you can use didSelectRowAt method of UITableViewDelegate.