exporting a 3d object i drew though the iOS platform

I grabbed the source code for a 3d line drawer here https://www.youtube.com/watch?v=GCOb4mI3u1E

and then i exported to iOS and was able to draw basic lines in 3d

can you guys point me to some documentation on how to save that final drawing to a new obj to load at a later time or to export it as an obj file so i can share it around as i choose?