title: In case of using Router with MVVM in Swift who is responsible for configuring presentation specific details?
body: <p>Example: A view controller is presented inside a navigation controller. It's navigation bar has a custom back button, a custom image in the center, and an action button whose state is dependent on the state of the view controller.</p>
  
  <p>The point of Router is to make the view controller oblivious of the context in which it's being presented. Yet in this case that would mean moving all of the navigation bar customizations and reactivity out of the view controller and somewhere else. Router is a no go as that would break the single purpose principle. How does one handle cases like this? Or do you just leave everything in the view controller and submit to the fact that the world isn't perfect? :)</p>