如何保存以音高变化录制的音频？

Question

我正在录制声音，然后改变音频的音高并保存。 我在录制语音后调用此方法，然后单击按钮更改音高，然后创建新文件但是无法听到音频，音频是用语音生成的，可能是错误？

-(void)saveEffectedAudioToFolder

{
NSError *error;
if (_audioEngine) {


    AVAudioUnitTimePitch *pitchEffect = [AVAudioUnitTimePitch new];



    pitchEffect.pitch = pitch;


    AVAudioFormat  * commonFormat = [[AVAudioFormat alloc] initWithCommonFormat:AVAudioPCMFormatFloat32 sampleRate:44100 channels:2 interleaved:NO];

    //
    AVAudioFile *outputFile = [[AVAudioFile alloc] initForWriting:[NSURL URLWithString:_filePathDstaud] settings:commonFormat.settings error:&error];

    if (error) {
        NSLog(@"Error is 1 %@",[error localizedDescription]);


    }


    [pitchEffect installTapOnBus: 0 bufferSize: 8192 format: commonFormat block: ^(AVAudioPCMBuffer *buffer, AVAudioTime *when)
     //here is that error 
     {

         if (outputFile.length < _audioFile.length)
         {
             //Let us know when to stop saving the file, otherwise saving infinitely
             NSError *error;

             NSAssert([outputFile writeFromBuffer:buffer error:&error], @"error writing buffer data to file, %@", [error localizedDescription]);

         }else{
             _audioEngine = nil;
             [pitchEffect removeTapOnBus:0];//if we dont remove it, will keep on tapping infinitely
             NSLog(@"Did you like it? Please, vote up for my question");
         }

     }


     ];
}
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

NSString *filePath = [documentsPath stringByAppendingPathComponent:name];

[fileManager removeItemAtPath:filePath error:&error];

}