switchFlashMode method

Implementation

void switchFlashMode() async {
  if (flashMode() == FlashMode.off) {
    await cameraController?.setFlashMode(FlashMode.always);
    flashMode.value = FlashMode.always;
  } else {
    await cameraController?.setFlashMode(FlashMode.off);
    flashMode.value = FlashMode.off;
  }
}