Wrap up

FrameExtractor.swift

    public func flipCamera() {
        sessionQueue.async { [unowned self] in
            self.captureSession.beginConfiguration()
            guard let currentCaptureInput = self.captureSession.inputs.first as? AVCaptureInput else { return }
            self.captureSession.removeInput(currentCaptureInput)
            guard let currentCaptureOutput = self.captureSession.outputs.first as? AVCaptureOutput else { return }
            self.captureSession.removeOutput(currentCaptureOutput)  
            self.position = self.position == .front ? .back : .front
            self.configureSession()
            self.captureSession.commitConfiguration()
        }
    }