检测按钮被点击的单元格

Question

On the FirstVC I have a variable index:

var index = -1

, which keeps the information of cell's indexPath.row so I can know in which cell the button was tapped. (Each cell has its own button)

I tried like this:
CellForRow :

cell.Btn.tag = indexPath.row
cell.Btn.addTarget(self, action: #selector(detectButton), for: .touchUpInside)

and then:

@objc func detectButton(sender: UIButton) {
    self.index = sender.tag
}

The secondVC is connected by the segue so I tried to send the index like this:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "MySegue" {
            let vc = segue.destination as! SecondVC
            vc.element = self.elements[index]
        }
    }

It crashes there because the index was still -1 . I thought that @objc func detectButton will be called before prepareForSegue but it is not.
Why? And is there any other solution to send the index to the secondVC?

Answer 1

You have to perform the segue *manually*:

• Reconnect the segue from the view controller (rather than from the table view cell) to the destination controller

• Delete var index = -1

• Replace

  @objc func detectButton(sender: UIButton) { self.index = sender.tag }

  with (note the underscore after the open parentheses)

   @objc func detectButton(_ sender: UIButton) { performSegue(withIdentifier: "MySegue", sender: sender.tag) }

• Replace

  override func prepare(for segue: UIStoryboardSegue, sender: Any?) { if segue.identifier == "MySegue" { let vc = segue.destination as. SecondVC vc.element = self.elements[index] } }

  with

  override func prepare(for segue: UIStoryboardSegue, sender: Any?) { if segue.identifier == "MySegue" { let vc = segue.destination as. SecondVC let index = sender as. Int vc.element = self.elements[index] } }

Edit:

Apparently in the current segue setup the button triggers the segue. If so delete var index = -1 and also the line cell.Btn.addTarget... (but not the line to assign the tag) and the entire method @objc func detectButton(_ sender: UIButton) {... } .

In prepare(for segue get the tag from the sender parameter

override func prepare(for segue: UIStoryboardSegue, sender: Any?) { if segue.identifier == "MySegue" { let vc = segue.destination as. SecondVC let index = (sender as. UIButton).tag vc.element = self.elements[index] } }