[Questions below]
I try to reimplement UIScrollView for various reasons and noticed that the first touch location recorded through touchhesBegan and touchsMoved has one random jump , usually among the first ~ 5 events.
Currently this exception will cause my implementation to move the scroll content a few pixels before smooth tracking is achieved.
This means that even if the finger moves at a constant speed, the distances between touch events are not (close) constant (= first touch. Slowed event is delayed and therefore does not smoothly correspond to finger movement).
This does not happen if the finger rests on several cycles of events. In addition, when testing on the iPad and using a pencil without coalescing / predictive touches, the experience is smooth and no jumps occur.
Based on this, I think the device needs a short amount of time to warm up before full 60 Hz touch tracking is available. Since the pencil will, even without a special pencil code, such as coalescing / prognostic, show no signs of a jump for the first few touches, it is reasonable to assume that the device heats up depending on the proximity of the tip to the screen (I remember this from some Apple presentations) combined with a higher sampling rate
Finally, using the simulator and trackpad to test this does not show any jumps at all, regardless of speed, supporting the wake-up phase for real iOS devices with finger input.
I could not find anything about this on the Internet, most likely, because I have no idea what to look for.
iPhone X iPad pro 10.5
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