AVAudioPlayer play issue with two sounds as echo - ios

Question

I have a separate View Controller that holds some Audio Message (URL with mp3 files). Here's the code I use to start playing a message:
- (void)playAudioMsg
{
[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategorySoloAmbient error: nil];
[[AVAudioSession sharedInstance] setActive: YES error: nil];
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:#"https://blahblahblah.mp3"]];
NSData *data = [NSData dataWithContentsOfURL:URL];
audioPlayer = [[AVAudioPlayer alloc] initWithData:data error:nil];
audioPlayer.numberOfLoops = 0;
audioPlayer.delegate=self;
[audioPlayer play];
}
The first time I open this view controller and click on a message to play, it plays just fine.
Then I dismiss a view controller.
Then I open it again and click on the same audio message. And what happens it's like two separate AVAudioPlayers got created - one of which starts playing audio right away and another is with a one-second delay (it sounds like the first message plays with echo.
Most interesting is when I dismiss a view controller then one message stops playing and another one keeps playing in the background even though when dismissing a view controller, I call [audioPlayer stop].
Can anyone help me with this, please?

Answer 1

I got the solution.
The problem comes from the fact that when I call -(void) playAudioMsg {...} I do it using this:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(playAudioMsg) name:#"playAudioMsg" object:nil];
... which is declared inside - (void) viewDidLoad {...}. But then I totally forgot to remove that observer when leaving the ViewController:
-(void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
[[NSNotificationCenter defaultCenter] removeObserver:self name:#"playAudioMsg" object:nil];
}
Without removing the observer and then coming back to the same page, it sets duplicate for the same observer, so the method playAudioMsg gets called twice.