if ([[captureManager backFacingCamera] isLowLightBoostEnabled]) {

    [[captureManager backFacingCamera] automaticallyEnablesLowLightBoostWhenAvailable];
}

if ([[captureManager backFacingCamera] respondsToSelector:@selector(lowLightBoostSupported)]) {
  if ([[captureManager backFacingCamera] lockForConfiguration:nil]) {
    [captureManager backFacingCamera].automaticallyEnablesLowLightBoostWhenAvailable = YES;
    [[captureManager backFacingCamera] unlockForConfiguration];
  }
}