title: Download .plist from server and save it locally in iPhone application
body: <p>I want to integrate in-app purchases into my application, and so I'd like to download .plist files whenever users buy new level sets. How can I download a file from a server and save it so that it stays in my iPhone app forever ?</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>I want to achieve something like that:</p>
  
  <ul>
  <li>As there are not many of these plists (never more than 20) I could just include them into the app and set a boolean value with <code>isPurchased</code> or so, right ?
  If the user purchased the category, the boolean is set to <code>YES</code>.
  Whenever new categories are added by me, I'll just have a whole new update like "Cut the rope" for instance do it. Is that a good approach ? </li>
  </ul>