dispatch_once accessing ivar in swift3

This was my code in 2.2 and I want this this to happen only once of an appliation cycle. But in swift 3 we do similar kind of stuff using gloabal static variable.

But the problem is that I can't access ivar from that closure, can anybody has some idea how to achieve this?

  static private var token: dispatch_once_t = 0
  override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)

    dispatch_once(&DashboardViewController.token) {
      self.myIvar = something;
    }
  }