This is pretty simple requirement.
2 * gps cordinates (longtude/latitude).
- current location (moving)
- target location
calculate the distance (pretty easy using clocation) between points.
calculate the equivalent SCNVector3 coordinates x,y,z and map (anchor scntext) in the current view. (label and distance to target)
may need to transform matrix to get correct bearing north..
The most important part of this work is the calculation to get the correct x,y,z for arkit.