Rumour has it that the next iPhone will have pressure-sensitive display. That means an item high up on my wishlist is coming to iPhone. I've blogged about this before.
3D-touch is not new. There are already pressure sensitive displays. One example is the company FlatFrog (www.flatfrog.com), which has displays in sizes 15-110 inch.
All the way from the start, iPhones have had a multi-touch-sensitive display. It was one of the reasons for iPhone's success, because it gave iPhone the famous pinch gesture. I still remember when I tried it out for the first time. At that time the iPhone was not for sale in Europe. A colleague had been to the US and bought an iPhone, and I was allowed to try it out. I was impressed.
Multi-touch is two-dimensional, 2D, i.e. when the user taps or swipes or pinches, an app receives information about it in terms of x and y, horizontal and vertical coordinates. With pressure sensitivity the app will receive a third parameter, which tells how hard the user pressed. That means we can call it 3D-touch.
For me the most obvious use of this feature is a scale app for weighing small and light items. But that's not what Apple has in mind. A new touch-type will probably be introduced: the force-touch, i.e. pressing harder. One good use for force-touch is to use it in a similar way the second button of a mouse is used (on Mac's one-button mouse it's done with Ctrl+click), and that is putting up a meny. Force-touch will be used for speeding up the user's interaction by reducing the number of presses he/she must do to accomplish something. Force-touch can also be used to reduce the number of user interface items on the screen, like buttons.
A possible use for 3D-touch is in games. Some games will benefit by testing the user's ability to use the right amount of pressure. The touch keyboard can most certainly be improved by 3D-touch, and thereby putting yet another nail in the coffin of hardware keyboards for mobile phones.