title: Proper way to implement Login/Logout in Storyboard
body: <p>I'm starting a new project in iOS7 and i need to implement OAuth 2 protocol to login.</p>
  
  <p>I understand that OAuth 2 define that i need to store the token &amp; refresh token to access to the resources in the server, and when i do the logout it must revoke this token in the server and delete it from the keychain right?.</p>
  
  <p>My question is what is the proper way to accomplish it, i have this example flow in storyboard:</p>
  
  <p><img src="https://i.stack.imgur.com/bpeaX.png" alt="enter image description here"></p>
  
  <p>Correct me if i'm wrong:</p>
  
  <ul>
  <li>In the "splash screen" VC i need to validate the token or refresh it right? or in some other point? </li>
  <li>If the token is valid i need to "popup" or "push" the Tabbar VC ?</li>
  <li>If the token isn't valid i need tu "popup" or "push" the login VC? 
  
  <ul>
  <li>When i have a success login i need to "popup" or "push" the Tabbar VC ?</li>
  </ul></li>
  <li>And the last case, when the user press "Logout", what i must to do? push to Login VC? what about memory ? i mean, i know in storyboard when u "navigate" you allocate every child vc in the memory, and it increase right? how i "restart" everything to the initial state of the app ?</li>
  </ul>
  
  <p>PS: My questions are about the Storyboard flow not about OAuth 2
  PS2: Sorry for my english, any corrections please tell me.</p>