Tracking position in 3d on mobile similar to Project Tango's SDK

I'm looking to try to use full 3d positional tracking on iphone. Reading Google Tango's documentation, it appears that this is possible using both motion tracking + camera using a method called visual-inertial odometry.

"Tango implements Motion Tracking using visual-inertial odometry, or VIO, to estimate where a device is relative to where it started."
https://developers.google.com/tango/overview/motion-tracking

I would love to be able to implement this on both iphone and...

Tracking position in 3d on mobile similar to Project Tango's SDK