Запись аудио: получить пустой файл

Question

Я пытаюсь записать аудио с AVAudioRecorder как объясняется во многих уроках. Я не получаю ошибки, но мой файл.caf все еще пуст после записи.

Мой код для запуска рекордера:

-(void)startRecordAudio:(NSString*)name {
    Shortcut *shortcut = XAppDelegate.currentShortcut;
    NSString *filePathWav = [shortcut getTmpFile:name];
    NSString *filePathCaf = [filePathWav stringByReplacingOccurrencesOfString:@".wav" withString:@".caf"];
    NSURL *tmpFileUrl = [NSURL fileURLWithPath:filePathCaf];

    // AUDIO SESSION
    AVAudioSession *audioSession = [AVAudioSession sharedInstance];
    NSError *err;
    [audioSession setCategory :AVAudioSessionCategoryRecord error:&err];
    if (err) {
        [self log:[err localizedDescription]];
        return;
    }
    err = nil;
    [audioSession setActive:YES error:&err];
    if(err){
        [self log:[err localizedDescription]];
        return;
    }
    if (!audioSession.isInputAvailable) {
        [self log:@"Le microphone n'est pas disponible. Veuillez réessayer"];
        return;
    }

    //AUDIO RECORDER
    NSDictionary *recordSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                [NSNumber numberWithInt: AVAudioQualityMedium], AVEncoderAudioQualityKey,
                                [NSNumber numberWithInt: kAudioFormatLinearPCM], AVFormatIDKey,
                                [NSNumber numberWithFloat:44100.0], AVSampleRateKey,
                                [NSNumber numberWithInt:16],AVEncoderBitRateKey,
                                [NSNumber numberWithInt: 2], AVNumberOfChannelsKey,
                                nil];
    NSError *error = nil;
    _recorder = [[AVAudioRecorder alloc] initWithURL:tmpFileUrl settings:recordSettings error:&error];
    if (error) {
        [self log:[error localizedDescription]];
    }
    [_recorder prepareToRecord];
    [_recorder record];

}

И остановить рекордер:

-(void)stopRecordAudio {
    [_recorder stop];
    AVAudioSession *session = [AVAudioSession sharedInstance];
    [session setActive:NO withOptions:AVAudioSessionSetActiveOptionNotifyOthersOnDeactivation error:nil];
    NSURL *inUrl = _recorder.url;
    NSURL *outUrl = [NSURL URLWithString:[[NSString stringWithFormat:@"%@", inUrl] stringByReplacingOccurrencesOfString:@".caf" withString:@".wav"]];
    [AudioConverter convertFile:inUrl toWav:outUrl];

    NSLog(@"Audio data : %@", [NSString stringWithContentsOfURL:inUrl encoding:NSUTF8StringEncoding error:nil]); // Result : (null)
}