Checking Segue after it initiated

Question

I have two UIViewController: A, B

Lets say there are two segues connecting them: C, D

Once a segue has been activated and I am in view B, can I know which segue got me here? C or D?

Answer 1

There is a prepare(for: segue) function that allows you to set a property in the new ViewController.

class OriginViewController : UIViewController {

    ...

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if let destination = segue.destination as? SegueProtocol {
            destination.transitionSegue = segue.identifier
        }
    }
}

class DestinationViewController : UIViewController, SegueProtocol {
    var transitionSegue: String = ""

    override func viewDidLoad() {
        print("Segue: ", transitionSegue)
    }
}

protocol SegueProtocol {
    var transitionSegue : String { get set }
}

Edit: As per comment suggestion, it's better to expect a destination that conforms to a protocol rather than one of a specific type.