title: iOS 7 auto brightness is overruling apps screen brightness setting
body: <p>I have an iOS 7 app where I want to make the screen darker. I am adjusting the screen brightness using the following line:</p>
  
  <pre><code>[UIScreen mainScreen].brightness = 0.3;
  </code></pre>
  
  <p>This dims the screen as I expect, but if a user has auto brightness enabled the screen sometimes goes back to its original setting. Is there a way to disable auto brightness while in my app, or do I need to subscribe to the UIScreenBrightnessDidChangeNotification notification and just reset the brightness each time it is raised?</p>