Dans Swift 4.1 et Xcode 10
Ici, AddFileViewController est le deuxième contrôleur de vue.
L'identifiant du storyboard est AFVC
let next = self.storyboard?.instantiateViewController(withIdentifier: "AFVC") as! AddFileViewController
self.present(next, animated: true, completion: nil)
let dashboard = self.storyboard?.instantiateViewController(withIdentifier: "DBVC") as! DashboardViewController
self.navigationController?.pushViewController(dashboard, animated: true)
Si nécessaire, utilisez du fil.
Ex: 
DispatchQueue.main.async { 
    let next = self.storyboard?.instantiateViewController(withIdentifier: "AFVC") as! AddFileViewController
    self.present(next, animated: true, completion: nil) 
}
Si vous voulez déménager après un certain temps.
EX: 
DispatchQueue.main.asyncAfter(deadline: .now() + 5.0) {
    let next = self.storyboard?.instantiateViewController(withIdentifier: "AFVC") as! AddFileViewController
    self.present(next, animated: true, completion: nil) 
}