title: iphone 4 sdk : detect return from background mode
body: <p>How can I detect that an app has just returned from "background mode"? I mean, I don't want my app to fetch data (each 60 sec) when the user press the "home button". But, I'd like to make some "special" update the first time the app is in foreground mode.</p>
  
  <p>How can I detect these two events:</p>
  
  <ol>
  <li>app going to background mode </li>
  <li>app going to foreground mode</li>
  </ol>
  
  <p>Thanks in advance.</p>
  
  <p>François</p>