title: How do I set up persistent authentication in a mobile app?
body: <p>All sorts of mobile apps - Gmail, Facebook, Pandora - have some persistent mechanism of authentication that enables a user to set up credentials once and then use them to automatically authenticate with their remote service in the future.  I'm probably blind, but I can't seem to find a tutorial anywhere out there that explains in simple terms how to properly do this on a mobile app.</p>
  
  <p>How do I build this functionality?  A link to a simple tutorial would be great.</p>