AVPlayer cannot remove a time observer that was added by a different instance of AVPlayer

AVPlayer 

An instance of AVPlayer cannot remove a time observer that was added by a different instance of AVPlayer.

解决办法

- (void)removeTimeObserver{
    //[self.player removeTimeObserver:self.playbackTimeObserver];
    
    @try{
        [self.player removeTimeObserver:self.playbackTimeObserver];
    }@catch(id anException){
        //do nothing, obviously it wasn't attached because an exception was thrown
    }
}

问题 原因 重复释放   playbackTimeObserver