The Cardboard iOS SDK is a development kit that provides developers a way to create their own Google Cardboard experience using Objective-C. This SDK enables developers to communicate their iPhone applications with the Google Cardboard service.
Google wants developers to make more immersive virtual reality environments for Google Cardboard. In order to help app writers do that, Google updated the Cardboard SDK to include support for spatial sound. In other words, VR apps are about to get a big boost in audio quality.
Google and Lenovo released the first Project Tango handset this week at CES. The phone includes an array of sensors that let apps cover real-world objects with digital overlays. It's sort of like augmented reality on steroids. Project Tango needs apps, and Google us willing to pay.