index of button in custom cell

Instead of using the segue, handle the navigation programatically through a closure in UITableViewCell.

class CustomCell: UITableViewCell {
    var buttonTapHandler: (()->())?

    @IBAction func onTapButton(_ sender: UIButton) {
        self.buttonTapHandler?()
    }
}

In the above code, I've create a buttonTapHandler - a closure, that will be called whenever the button inside the cell is tapped.

Now, in cellForRowAt method when you dequeue the cell, set the buttonTapHandler of CustomCell.

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "CustomCell", for: indexPath) as! CustomCell
    cell.buttonTapHandler = {[weak self] in
        if let mapVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "MapViewController") as? MapViewController {
            mapVC.place = places[indexPath.row]
            self?.navigationController?.pushViewController(mapVC, animated: true)
        }
    }
    return cell
}

In the above code, buttonTapHandler when called will push a new instance of MapViewController along with the relevant place based on the indexPath.

if you don't want to execute your code in didSelectRowAt method, another good approach in my opinion is to create a delegate of your custom cell. See the code below

// This is my custom cell class
class MyCustomCell: UITableViewCell {

    // The button inside your cell
    @IBOutlet weak var actionButton: UIButton!
    var delegate: MyCustomCellDelegate?

    @IBAction func myDelegateAction(_ sender: UIButton) {
        delegate?.myCustomAction(sender: sender, index: sender.tag)
    }

    // Here you can set the tag value of the button to know
    // which button was tapped
    func configure(index: IndexPath){
       actionButton.tag = index.row
    }

}

protocol MyCustomCellDelegate {
    func myDelegateAction(sender: UIButton, index: Int)
}

Delegate the ViewController where you use your custom cell.

class MyViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
      let cell = tableView.dequeueReusableCell(withIdentifier: "MyCellIdentifier", for: indexPath) as! MyCustomCell

      cell.configure(index: indexPath)
      cell.delegate = self

      return cell
    }
}

And at the end customize your method extending your custom cell delegate

extension MyViewController: MyCustomCellDelegate {

    func myDelegateAction(sender: UIButton, index: Int) {
        // Do your staff here
    }
}

I hope I was helpful.

In the custom cell:

import UIKit

protocol CustomCellDelegate: class {
    func btnPressed(of cell: CustomCell?)
}

class CustomCell: UITableViewCell {

    weak var delegate: CustomCellDelegate?

    @IBAction func btnTapped(_ sender: UIButton) {
        delegate?.btnPressed(of: self)
    }

}

And in the view controller:

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell: CustomCell = tableView.dequeueReusableCell(for: indexPath)
        cell.delegate = self

        return cell
    }

    extension ViewController: CustomCellDelegate {

    func btnPressed(of cell: CustomCell?) {
        if let cell = cell, let indexPath = tableView.indexPath(for: cell) {
            // Your stuff here
        }
    }

}