title: Snapchat style multiple ViewController access
body: <p>In Snapchat, you can swipe left or right and access an entirely different UIViewController, from the camera to tableviews.</p>
  
  <p>It appears that all viewControllers are kept live and retained, so switching between them is smooth and doesn't require any kind of transition.</p>
  
  <p>Does anyone know how this is achieved or can point me in the right direction? Thanks</p>