I have found a system bug with UINavigationController, UIGestureRecognizerDelegate mainly the swipe back control.
I have reproduced this in many apps, while some that use custom swipe back i can not reproduce, however any app using default uikit/swift transitions i can reproduce the flicker/previous screen flashing
The Bug: a slight tap or series of quick taps anywhere on the screen (with the slightest (1-2pt -x)confuse the system into thinking its a swipe back gesture, however instead of pushing back to previous screen the UI flickers and flashes the previous screen. for a split second, very easy to reproduce.
on screens with lots of options of boxes to tap it happens quite often.
I have removed all custom "swipe back from anywhere" logic, all custom gesture logic, and can still reproduce by tapping the edge of the screen with only UINavigationController, UIGestureRecognizerDelegate in my navigation controller.
Please let me know the best way to get in contact with someone at apple to either build an extension to prevent this flicker or if a developer has a fix but this is rarely talked about. (velocity limits etc do not work, and just make the gesture feel awful)
all the developers i have reached out too have looked into this and have said "its an ios bug, only fix is build a custom swipe back from anywhere, or wait for apple to fix it).... as a small indie app, building my own seems daunting
Recap: quick or taps with small x movement flash previous screen instead of pushing back or simply recognizing it as a tap and not flashing previous screen. this happens with no custom code default uikit/swift. Link me your app i can probably reproduce it, I have reproduced it in X(was hard), Retro(easy), and many more.
The goal is to have a smooth native swipe/drag back from anywhere gesture while preventing flicking on fast taps or short taps with minor x movement. i have tried everything from setting limits to -x, velocity limits etc. nothing fixes this.
happy hacking! PS i hope someone at apple calls me and i can explain this and we can fix it for every app in an update.