title: How to set System volume programmatically in iOS
body: <p>i am getting System volume from following code</p>
  
  <pre><code>[[NSNotificationCenter defaultCenter]
        addObserver:self
        selector:@selector(volumeChanged:)
        name:@"AVSystemController_SystemVolumeDidChangeNotification"
        object:nil];
   - (void) volumeChanged:(NSNotification *)  
   {
       float volume = [[[notification userInfo]
                       objectForKey:@"AVSystemController_AudioVolumeNotificationParameter"]
                       floatValue];
  
       // here volume is the .....
   }
  </code></pre>
  
  <p>but how to set system or devices volume from xcode (Objective C)</p>