Having tested SDK mobilesdk-7.5.0.v20180821233900-osx to try the new (long-awaited) AVPlayer-based Ti.Media.audioPlayer I have discovered a crucial bug.
After setting up a player and then using `player.setUrl(URL)` it works fine.
If you then try to setUrl again, the app will crash.
This is due to the notification observer for "timedmetadata" not being removed.
To fix the issue, please add one line to TiMediaAudioPlayerProxy.m at line 422:
[[[self player] currentItem] removeObserver:self forKeyPath:@"timedMetadata"];