Possibility to get sole GPS Altitude from CLLocationManager

I am developing an iOS app in the field of aviation. Now I have a feature request of a customer that requires to solely use the ellipsoid height (WGS84) for calculations. I know from another question / answer that the CLLocationManager returns the converted geoid height via its "altitude" property. Is there any possibility to get the ellipsoid height (WGS84) or the used geoid undulation to translate the given geoid height from CLLocationManager back to ellipsoid height? If not does anyone know a third party lib for conversion using EGM2008?