Note that enabling "Back Tap" will cause a daemon to run in the background all times taking a couple percent CPU (to detect this action, of course). I don't have very good numbers of the battery life impact but my guess is that it's perhaps half an hour or so. Might be worth keeping in mind when deciding whether to enable this feature.
> Note that enabling "Back Tap" will cause a daemon to run in the background all times taking a couple percent CPU
Is this true? I was under the impression that iPhones (and most modern high end devices) had dedicated hardware to monitor these sort of features, and triggers a system event in the OS (the same way you don’t need a daemon to check for a keyboard or power button).
It is, the process is named "AccessibilityUIServer". There is a dedicated motion coprocessor but when the events come back the are plumbed through CoreMotion to a framework called Phoenix, which runs a ML model on them.
This is a primary source :) Something needs to handle those interrupts. Perhaps this stack trace from the profiler may be enlightening as to what that thing is:
