title: Using AVMutableComposition iPhone
body: <p>I am using the below code, for streaming the two videos sequentially. But it is not showing any video in the simulator, its totally blank. </p>
  
  <p>Also how can I seek through these two videos. Like, if one video is of 2 minutes and the second is 3 minutes. Now I need to get the total time of these videos and seek through them. When I slide the slider bar to 4 minutes so the 2nd video should be played from minute 2 to onward.</p>
  
  <p>Is it possible?</p>
  
  <pre><code>- (void)viewDidLoad
  {
      [super viewDidLoad];
      // Do any additional setup after loading the view, typically from a nib.
  
      NSURL *url1 = [NSURL URLWithString:@"http://www.tools4movies.com/dvd_catalyst_profile_samples/Harold%20Kumar%203%20Christmas%20bionic.mp4"];
      NSURL *url2 = [NSURL URLWithString:@"http://www.tools4movies.com/dvd_catalyst_profile_samples/Harold%20Kumar%203%20Christmas%20tablet.mp4"];
  
      NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:AVURLAssetPreferPreciseDurationAndTimingKey];
  
      AVMutableComposition *composition = [[AVMutableComposition alloc] init];
  
      asset1 = [[AVURLAsset alloc] initWithURL:url1 options:options];
      AVURLAsset * asset2 = [[AVURLAsset alloc]initWithURL:url2 options:options];
  
      CMTime insertionPoint = kCMTimeZero;
      NSError * error = nil;
      composition = [AVMutableComposition composition];
  
      if (![composition insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset1.duration) 
                                ofAsset:asset1 
                                 atTime:insertionPoint 
                                  error:&amp;error]) 
      {
          NSLog(@"error: %@",error);
      }
  
      insertionPoint = CMTimeAdd(insertionPoint, asset1.duration);
  
      if (![composition insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset2.duration) 
                                ofAsset:asset2 
                                 atTime:insertionPoint 
                                  error:&amp;error]) 
      {
          NSLog(@"error: %@",error);
      }
  
      AVPlayerItem * item = [[AVPlayerItem alloc] initWithAsset:composition];
      player = [AVPlayer playerWithPlayerItem:item];
      AVPlayerLayer * layer = [AVPlayerLayer playerLayerWithPlayer:player];
  
      [layer setFrame:CGRectMake(0, 0, 320, 480)];
      [[[self view] layer] addSublayer:layer];
      [player play];   
  }
  </code></pre>
  
  <p>Can anyone tell me that what is the error in my code?</p>