Play different music in a short period of time，the player can not be stopped

[a363211861]

In my viewController， call the playInfo: function many times in a short period of time，then pop the viewController(viewDidDisappear: is called)，music is still playing。

-(void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:animated];

[_audioPlayer stop];
_audioPlayer.delegate = nil;
_audioPlayer = nil;

}

-(void)playInfo:(NSDictionary *)info
{
self.musicInfo = info;

if (_audioPlayer) {
    [_audioPlayer stop];
    _audioPlayer.delegate = nil;
}
_audioPlayer = [[AudioPlayer alloc] init];
_audioPlayer.delegate = self;

NSURL *url = [self getPlayURL:info];
[_audioPlayer setDataSource:[_audioPlayer dataSourceFromURL:url] withQueueItemId:url];
}

[a363211861]

I found dealloc method of audioPlayer never been called，In my project.  I think the reason may be retain cycle on self with blocks。 such as the code:
[fastApiQueue addOperationWithBlock:^
{
pthread_mutex_lock(&playerMutex);
{
.......
[self clearQueue];
.......
}
pthread_mutex_unlock(&playerMutex);
}];