prepareForSegue and PerformSegueWithIdentifier sender

Question

I am wondering about how the functions in the title work and also about the sender parameter.

Lets say a button click calls the performSegue method, does that also call

Answer 1

my two cents for beginners... In swift 3 is:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

}

So, if arriving controller (of class MyController) implements a "fillData" method:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

    if let destController = segue.destination as MyController{

        destController.fillData(...)
    }

}