title: CAKeyframeAnimation not visible on video
body: <p>I'm making an app to manipulate video, now I m adding sprite animation above the video.</p>
  
  <p>For that I m using CAKeyframeAnimation, I have a method in a Manager that is adding the animated sprite.</p>
  
  <pre><code> // add effect on the video
  [EffectManager addEffectOnVideoAtURL:outputURL handler:^{
    NSLog(@"video exported with aimations");
  }];
  </code></pre>
  
  <p>The thing is that when this videoURL is stored in the document folder of my app, the CAKeyframeAnimation is not visible.</p>
  
  <p>But when I first export the video to the Library/camera roll, and then load and add the effect on this exported video, they are visible.</p>
  
  <pre><code>ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
   // export the video to the library/camera roll
  if ([library videoAtPathIsCompatibleWithSavedPhotosAlbum:outputURL]) {
      [library writeVideoAtPathToSavedPhotosAlbum:outputURL completionBlock:^(NSURL *assetURL, NSError *error){
          dispatch_async(dispatch_get_main_queue(), ^{
                // add effect on the video
                [EffectManager addEffectOnVideoAtURL:assetURL handler:^{
                   NSLog(@"video exported with aimations");
                  }];
          });
      }];
  }
  </code></pre>
  
  <p>This code, using the library is working correctly, but I don t want to have to save a intermediate video to the library.</p>
  
  <p>I have tried to use the first snippet of code in a async way, but the result is the same.</p>
  
  <p>I have tried also to load a movie from the library, and use the first snippet of code, but same result, no CAKeyframeAnimation.</p>
  
  <p>Any idea why CAKeyframeAnimation is visible only when the video is first exported to the lbrary/photo roll ?</p>