title: Store a user profile in iOS app so that it's always accessible
body: <p>I want to create a user that the app fetches from disk every time the app is opened, and written every time it is closed. I want the data from the user, such as <code>NSString</code> name, along with some other variables, to be accessible from any other point in the app. </p>
  
  <p>There will only be one user so it is kind of a "global" variable. Also, if the user class includes pointers to data structures like <code>NSMutableDictionary</code>, or another instance of <code>NSObject</code>, are there any precautions I need to take?</p>
  
  <p>I want to learn the best way to implement this, any suggestions?</p>