title: iOS 6 issue Convert MPMediaItem to NSData
body: <p>i had tried the below code.</p>
  
  <pre><code>   -(void)mediaItemToData : (MPMediaItem * ) curItem
  {
      NSURL *url = [curItem valueForProperty: MPMediaItemPropertyAssetURL];
  
      AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL: url options:nil];
  
      AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset: songAsset
                                                                        presetName:AVAssetExportPresetPassthrough];
  
      exporter.outputFileType =  @"public.mpeg-4";
  
      NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
      NSString * myDocumentsDirectory = ([paths count] &gt; 0) ? [paths objectAtIndex:0] : nil;
  
      NSString *exportFile = [myDocumentsDirectory stringByAppendingPathComponent:
                              @"exported.mp4"];
  
      NSURL *exportURL = [NSURL fileURLWithPath:exportFile];
      exporter.outputURL = exportURL;
  
      // do the export
      // (completion handler block omitted)
      [exporter exportAsynchronouslyWithCompletionHandler:
       ^{
           NSData *data = [NSData dataWithContentsOfFile: [myDocumentsDirectory
                                                           stringByAppendingPathComponent: @"exported.mp4"]];
  
           DLog(@"Data %@",data);
       }];
  }
  </code></pre>
  
  <p>this code is working fine in iOS 5 but now working in iOS 6.  </p>
  
  <p>Any changes for iOS6 in <code>AVAssetExportPresetPassthrough</code>. ???</p>