需要一些关于AVAudioPlayer的帮助

Question

这是录制和播放音频的代码，它完美地创建音频文件，但播放代码不播放文件。我无法理解出了什么问题我尝试了所有的nslog，音频文件也在文档文件夹中完美生成。

- (IBAction)recStartStop:(id)sender
{
    if(toggle)
    {
        [recStartStopBtn setImage:[UIImage imageNamed:@"StopRed"] forState:UIControlStateNormal];
        toggle = NO;
        playBtn.enabled = toggle;
        playBtn.hidden = !toggle;
        NSMutableDictionary* recordSetting = [[NSMutableDictionary alloc] init];
        [recordSetting setValue :[NSNumber numberWithInt:kAudioFormatAppleIMA4] forKey:AVFormatIDKey];
        [recordSetting setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey];
        [recordSetting setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey];
        recordedTmpFile = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent: [NSString stringWithFormat: @"%.0f.%@", [NSDate timeIntervalSinceReferenceDate] * 1000.0, @"caf"]]];
        NSLog(@"Using File called: %@",recordedTmpFile);
        recorder = [[ AVAudioRecorder alloc] initWithURL:recordedTmpFile settings:recordSetting error:nil];
        [recorder setDelegate:self];
        [recorder prepareToRecord];
        [recorder record];
    }
    else
    {
        recStartStopBtn.enabled = NO;
        recStartStopBtn.hidden = YES;
        playAudioBtn.hidden = NO;
        NSLog(@"Using File called: %@",recordedTmpFile);
        [recorder stop];
    }
}

- (IBAction)playAudio:(id)sender
{
    AVAudioPlayer * avPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:recordedTmpFile error:nil];
    [avPlayer prepareToPlay];
    [avPlayer play];

    NSLog(@"%@",recordedTmpFile);
}