iOS 14 AVCaptureSession capturing stereo audio with video recording

Question

I was wondering is there's a way to capture stereo audio using an AVCaptureSession. iOS 14 adds support for stereo audio for AVAudioRecorder, but so far I have been unsuccessful is capturing stereo audio through an AVCaptureSession.

AVAudioSession *audioSession = [AVAudioSession sharedInstance];
[audioSession setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker error:nil];
[audioSession setActive:YES error:NULL];
     
NSArray *portDescriptions = audioSession.availableInputs;
AVAudioSessionPortDescription *builtInMicPort = nil;

for (AVAudioSessionPortDescription *port in portDescriptions) {
    if ([port.portType isEqualToString:AVAudioSessionPortBuiltInMic]) {
        builtInMicPort = port;
        break;
    }
} // end input iteration
     
[audioSession setPreferredInput:builtInMicPort error:nil];
     
NSArray *supportedPolarPatterns = audioSession.preferredInput.dataSources.firstObject.supportedPolarPatterns;
         
[audioSession.preferredInput.dataSources.firstObject setPreferredPolarPattern:AVAudioSessionPolarPatternStereo error:nil];


[audioSession.preferredInput setPreferredDataSource:audioSession.preferredInput.dataSources.firstObject error:nil];
[audioSession setPreferredInputOrientation:AVAudioStereoOrientationPortrait error:nil];

device = [AVCaptureDevice defaultDeviceWithDeviceType:AVCaptureDeviceTypeBuiltInWideAngleCamera mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionBack];
deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];

if([videoSession canAddInput:deviceInput]){
    [videoSession addInput:deviceInput];
}

AVCaptureDevice *audioDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
AVCaptureDeviceInput *audioDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:audioDevice error:&error];
        
if([videoSession canAddInput:audioDeviceInput]){
    [videoSession addInput:audioDeviceInput];
}

Answer 1

Try this:

videoSession.usesApplicationAudioSession = true
videoSession.automaticallyConfiguresApplicationAudioSession = false

I was able to get stereo working in iOS 14 with this added.