Swift : prepareForSegue with navigation controller

Question

I am developing an iOS application in Swift.

I want to send data from a view to an other one, using the prepareForSegue function.

However, my target view is

Answer 1

A one liner in Swift 3:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
  if let vc = segue.destination.childViewControllers[0] as? FooController {
    vc.variable = localvariable
  }
}