11/11/2016 - version 1.1 If run on a 3D Touch device, also shows the 3D touch value as a colored pie chart, where maximum pressure is a 360° sweep.
10/24/2015 - asset catalogs. Icon.
10/03/2015 - Demonstrates that Pre-6s hardware can detect the difference between a light touch and a heavy one. iOS 8 and up.
Yes, it's really the major radius of the contact area of the touch, but close enough for you to play around with it.
There's no library here. The entire app is about UITouch's property majorRadius
In Xcode, change the Project's Target's general settings, 'bundle id to yours, set up your team, and compile and run it on your device.
Try touching lightly. Try touching hard. You can touch with multiple fingers at once.
Sample screen shot, landscape mode. Multiple fingers on the device:
Not all of your friends have 3D Touch capable hardware. In debug builds of your app, you can use the majorRadius of the touch as a substitute for the force level, since human fingers make a larger contact with the glass as you press harder.
LevelsOfPressure is a demo app, where you can see what that's like on your own devices. For a light touch, it draws a circle around your fingertip. As you press harder, it draws more concentric circles, the number is proportional to how hard you press.
The mapping between majorRadius and the number of circles is pretty arbitrary. You might want to experiment with that.
The numeric values, in the order the fingers touch the display, are graphed at the bottom.
majorRadius was introduced in iOS 8.
If you do have 3D Touch hardware, then the value of the touch is shown as a pie chart scaled so maximum force lights the entire circle of the pie chart. Apple has a concept of a normal-force touch. Those are shown in green. Light touches are blue, and heavy are yellow, with red being maximum force.
by David Phillip Oster
Apache Version 2 License