gistfile1.swift

// The variable `delegate` property of `UINavigationController` is defined as `unowned`.
// 
// Given a case in which that `delegate` must be retained, is this the best pattern for doing so?

class CustomNavigationController: UINavigationController {

  override var delegate: UINavigationControllerDelegate? {
    didSet {
      self.strongDelegate = delegate
    }
  }

  private var strongDelegate: UINavigationControllerDelegate?

}