3D Touch is a function of pressure: "How hard has the user pressed?"

In practice, things that your application previously accomplished with long presses may be more suitably accomplished with 3D Touch — things like contextual menus or shortcuts come to mind. Additionally, iOS has new APIs for presenting content using 3D Touch. The article briefly references them.

(1) https://developer.apple.com/library/prerelease/ios/documenta...