- (void)locationManager:(CLLocationManager *)manager didEnterRegion:(CLRegion *)region
{
    NSLog(@"MapViewController - didEnterRegion");
    NSLog(@"MVC - didEnterRegion - region.radius = %f", region.radius);

    // code to get the url (removed for simplicity)

    AVAudioSession *audioSession = [AVAudioSession sharedInstance];

    [audioSession setCategory:AVAudioSessionCategoryPlayback error:nil];
    [audioSession setActive: YES error: nil];
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];

    self.regionPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
    NSLog(@"self.regionPlayer.url = %@",self.regionPlayer.url);
    [self.regionPlayer play];
}

Sep 12 22:33:47 unknown MLTM[4995] <Warning>: MVC - didEnterRegion - region.radius = 250.000000
Sep 12 22:33:47 unknown MLTM[4995] <Warning>: url = file://localhost/var/mobile/Applications/EFD6A583-5685-4D7C-BF8E-C8CFEA9E0D03/MLTM.app/party%20mix%207.caf
Sep 12 22:33:47 unknown MLTM[4995] <Warning>: self.regionPlayer.url = file://localhost/var/mobile/Applications/EFD6A583-5685-4D7C-BF8E-C8CFEA9E0D03/MLTM.app/party%20mix%207.caf
Sep 12 22:33:48 unknown Console[4179] <Notice>: TestFlight: Team Token is recognized
Sep 12 22:33:48 unknown mediaserverd[44] <Error>: 22:33:48.087 <AudioQueueServer> AudioQueue: Error -12985 from AudioSessionSetClientPlayState(4995)

register **UIBackgroundModes** in info.plist for background playing
 [[AVAudioSession sharedInstance] setDelegate: self];
 [[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryAmbient error: nil];