Completion handler is not called on iOS7 GM

Question

I\'m using AVAssetWriter, and it is perfectly working on iOS6.

The problem is, when I called finishWritingWithCompletionHandler, the completion handler

Answer 1

Retaining the assetwriter is very important but I also ran into a very strange intermittent failure even though my assetwriters were all retained (and never reused). The problem also wasn't a file name collision or missing directory because my file names are all based on CACurrentMediaTime() and don't change directories.

It seems if you don't set endSessionAtSourceTime: for the assetwriter every time, there's a very rare (but reproducible) chance the completion handler for finishWritingWithCompletionHandler: won't ever be called. If you wait a few seconds and check on the status of the assetwriter, it will be in the AVAssetWriterStatusFailure state and the error will be a non-descript "An unknown error occurred (-12763)". Additionally, changing the file format for the assetwriter doesn't see to have an effect on this problem. Lastly, this problem is probably only an issue if you need to rapidly record movies over and over again (as the chance for failure is probably 1/15 - 1/20).

So, just be sure to store the presentation time stamp for the last sample you're passing to the assetwriter and to call endSessionAtSourceTime: with that sample time right before you're about to call finishWritingWithCompletionHandler:.