title: Changing root view controller of a iOS Window
body: <p>Is the root view controller of a iOS Window usually initialized once in the beginning to a tab bar controller or navigation controller?  Is it okay to change the root view controller multiple times within an app?</p>
  
  <p>I have a scenario where the top view is different based on user action. I was thinking of having a navigation controller with the top view controller having the image of the splash screen, and pushing/popping view controllers as required. Alternately, I can keep changing the window's top view controller. Which will be a better approach?</p>