Convert latitude and longitude to ECEF coordinates system

Question

I am studying pArk Apple sample code, and how it is works. anyone knows how convert the latitude and longitude to ECEF coordinates, and Covert ECEF to ENU coordinates center

Answer 1

The latLonToEcef method is an implementation of the algorithm outlined in the Geographic coordinate conversion - From geodetic to ECEF coordinates wikipedia page:

where

Φ is latitude, λ is longitude, and

Likewise the ecefToEnu method is an implementation of the ECEF to ENU algorithm:

If you need further references, they can be found at the bottom of that Wikipedia page. You might also refer to the World Geodetic System 1984 spec.