I'm posting a screen shot from my iPad to demonstrate a problem with touches delivered by the Apple Pencil. In the demo app, I stroke the pencil across the glass left to right. Each touch is drawn with a black dot, each coalesced touch is drawn with a red dot. For each touch I draw three data as whiskers perpendicular to the direction of motion. The green whisker represents the elapsed time since the last touch. The orange whisker represents the distance traveled since the last touch but magnified so that it's easier to see. The purple whisker is the velocity, that is, the orange whisker divided by the green whisker.
On my 240Hz iPad Pro, the delta time should be a constant 4.166... milliseconds. Instead I get some 4 millisecond intervals, some 3 millisecond and some 5 millisecond. Look at the green whiskers.
The smoking gun here is that the time intervals are EXACT integral millisecond values. (I see this in a log file that I'm not including here.) Someone someplace is rounding the true time stamp from the hardware to the nearest millisecond. This completely breaks what I'm trying to do with my data models.
Notice the profound effect this has on the velocities. I'm getting an artificial beat frequency that could not come from the acceleration of any human hand. This breaks any ability to train on velocities over small displacements--which is fundamental to my app. Please deliver the true time stamp in the touch events.
(This demo was run on a 9.7in iPad Pro, Pencil v1.)