A mistake in your code

[yangoo1991]

Thanks for your code, it helps me a lot. But I found there's a mistake in the model named "DNAsset".

• (BOOL)isEqualToAsset:(DNAsset *)asset
  {
  if ([asset isKindOfClass:[DNAsset class]]) {
  return [asset.url isEqualToOther:asset.url]; // You must mean [self.url isEqualToOther:asset.url];
  } else {
  return NO;
  }
  }

[dennisxiaoding]

Thanks a lot!