Play an MP3 on an iPhone on button click not working?

Here i code for playing mp3 song on button click . I have tried all similar question but they are not working .How i can get it working ?

- (void)SingButtonAction:(id)sender
{  
    NSURL *url = [[NSBundle mainBundle] URLForResource:@"sms" withExtension: @"mp3"];
    if (!url){NSLog(@"file not found"); return;}
    NSError *error;

    AVAudioPlayer *audioPlayer = [[AVAudioPlayer alloc]
                                  initWithContentsOfURL:url
                                  error:nil];
    [audioPlayer play];
}