A duplicated segue processing with UIStoryBoardSegue between two UIViewControllers

Question

I have two screens. The first is based on UITableView instance. When I tap cell, function tableView(_:didSelectRowAt:) triggers:

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    selectedEmg = selectedEmergencies[indexPath.row]
    performSegue(withIdentifier: "ShowMoreInfoAboutEmg", sender: self)
}

Here is storyboard:

But in fact, the segue "ShowMoreInfoAboutEmg" duplicates itself and second screen.

I can cut performSegue(withIdentifier:sender:) and the transition between screens will work correctly. However I need to transfer data from UITableViewCell instance to remote UIViewController's property. Otherwise I get something like this:

prepare(for:sender:) starts to work earlier than tableView(_:didSelectRowAt:) and remote view controller gets nil object from cell. Any tips, guys?

The decision is found.

The simple and useful UITableView's property indexPathForSelectedRow.

I didn't touch my storyboard but I removed tableView(_:didSelectRowAt:) implementation completely and just have added one line. It's enough to use prepare(for:sender:) totally. The general implementation is something like below:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "SomeCustomIdentifier" {
            guard let remoteViewController = segue.destination as? CustomViewController else {
                fatalError("CustomViewController instance is not found ")
            }
            selectedItem = items[(self.customTableView.indexPathForSelectedRow?.row)!]
            remoteViewController.selectedItemFromTable = selectedItem
        }
}

Answer 1

Maybe it will be much simpler:

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let selectedEmg = selectedEmergencies[indexPath.row]
    if let vc = storyboard?.instantiateViewController(withIdentifier: "EmgDetailsPresenter") as? EmgDetailsPresenter {
        vc.selectedEmgFromTable = selectedEmg
        navigationController?.pushViewController(vc, animated: true)
    }
}

P.S. Don't forget to remove segue in Storyboard and add Storyboard ID to EmgDetailsPresenter

Answer 2

So basically you're calling didselectrow from the code and also the segue from the cell in the story board. Delete the segue linking the cell in the Showmoreinfoaboutemg. Then create a segue from the whole showmoreinforaboutemg viewcontroller to the the one it is supposed to go to. Give it the same reuse identifier and problem solved

Edit: the issue is that you are calling the segue twice once on click in the story board and the select time on click in the code with did select row.