AVAudioPlayer播放没有声音

在- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions中加入这句话


    [[AVAudioSession sharedInstance]setCategory:AVAudioSessionCategoryPlayback error:nil];

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
       NSString * resourcePath = [[NSBundle mainBundle] pathForResource:@"SIMS_BreathingSpace_100215" ofType:@"mp3"];
//    NSString * resourcePath = [[NSBundle mainBundle] pathForResource:@"time" ofType:@"mp3"];
    //    NSString * resourcePath = [[NSBundle mainBundle] pathForResource:@"time" ofType:@"mp3"];
    NSData  *data =[NSData dataWithContentsOfFile:resourcePath];
    audioPlayer = [[AVAudioPlayer alloc]initWithData:data error:nil];
    audioPlayer.delegate = self;
    audioPlayer.volume = 0.8f;
    [audioPlayer prepareToPlay];
    
}


-(IBAction)play:(id)sender
{
    [audioPlayer play];
}

stackover上有解释，看的不大懂http://stackoverflow.com/questions/4640880/mp3-playing-using-avaudioplayer-not-working-on-device点击打开链接