Use the audio IO manager

main.m

// how to create an audio IO manager. You should do this right after the SDL manager is created
self.audioManager = [[SDLAudioIOManager alloc] initWithManager:self.sdlManager delegate:self];
self.audioManager.inputStreamPrompt = [[SDLTTSChunk alloc] initWithText:SDLPrerecordedSpeechListen type:SDLSpeechCapabilitiesPrerecorded];
self.audioManager.inputStreamText = @"Listening...";

// how to start the audio IO manager. Whenever the user presses the mic button on the screen
[self.audioManager startInputStream]; // this is it

// how to stop the audio IO manager if you have recognized user input
[self.audioManager stopInputStream];

// output stream related (custom speech, voice instructions)
- (void)audioManagerDidStartOutputStream:(SDLAudioIOManager *)audioManager {
    NSLog(@"%s", __FUNCTION__);
}
- (void)audioManagerDidStopOutputStream:(SDLAudioIOManager *)audioManager {
    NSLog(@"%s", __FUNCTION__);
}
- (void)audioManager:(SDLAudioIOManager *)audioManager didFinishPlayingURL:(NSURL *)url {
    NSLog(@"%s", __FUNCTION__);
}
- (void)audioManager:(SDLAudioIOManager *)audioManager errorDidOccurForURL:(NSURL *)url error:(NSError *)error {
    NSLog(@"%s", __FUNCTION__);
}

// input stream related (driver speaking)
- (void)audioManager:(SDLAudioIOManager *)audioManager didStartInputStreamWithOptions:(SDLAudioPassThruCapabilities *)options {
    NSLog(@"%s", __FUNCTION__);
    [self.audioRecorder startAudioRecordingToFileAtPath:self.audioFile amplifierMode:SDLAudioRecorderAmplifierModeLiveProcessing capabilities:options];
}
- (void)audioManager:(SDLAudioIOManager *)audioManager didReceiveAudioData:(NSData *)audioData {
    NSLog(@"%s", __FUNCTION__);
    [self.audioRecorder writeAudioData:audioData];
}
- (void)audioManager:(SDLAudioIOManager *)audioManager didFinishInputStreamWithResult:(SDLResult)result {
    NSLog(@"%s", __FUNCTION__);
    if ([result isEqualToEnum:SDLResultSuccess]) {
        [self.audioRecorder finishAudioRecording];
        [self playAudio]; // just an example what to do with the audio
    } else {
        [self.audioRecorder cancelAudioRecording];
    }
}