This application is modifying the autolayout engine from a background thread after the engine was accessed from the main thread. This can lead to engine corruption and weird crashes.

If you ever see this error in your console, it’s because you are trying up update the UI from the main thread.

The fix is simple. Find where you are doing the update, and that code on a background thread.

dispatch_async(dispatch_get_main_queue(), ^{
[self updateSubViewsWithTrack:track];