Open Radar

 
Area:
App Switcher

Summary:
On iOS10 iPhone 6s/7, when swiping inwards from the left side margin of the screen, touch inputs are intercepted by the 3D touch gesture even if not recognized as the press gesture. This causes fast, inward touches and swipes to fail to propagate to the front most app correctly. When touches get sent to the app, they will often start inside this left side margin and not where they touch actually originated. For games and other apps that rely on fast user input on all parts of the screen, this causes significant errors and performance degradation.

Steps to Reproduce:
1. Enable 3D Touch.
2. Launch any game or app that detects touches on the left side of the screen.
3. Quickly, lightly drag a finger from the edge of the device inwards across the left margin. *Do NOT press firmly enough to trigger the 3D Touch app switcher.
4. The app switcher does not activate (correctly).
5. Touches passed into the app are clamped (incorrectly) in their location to inside of the margin and begin in the interior of the screen.

6. Do this same gesture from the right side instead. Touches correctly start at the screen edge.

7. Do this same gesture from the left with the same app on iOS 9. The problem does not exhibit and touches correctly begin at the edge of the screen.

Expected Results:
Touch events should not be intercepted or blocked by the App Switcher if the force value of the 3D Touch does not pass the activation threshold.

Actual Results:
While 3D Touch is active, regardless of the force value of a touch, the touch is intercepted by the App Switcher and discarded. Touch events that make it to the underlying front-most app are missing the part of the gesture that began in the margin of the screen.

Version:
iOS 10.0.2 (14A456)

Notes:
Disabling 3D Touch in the system settings avoids this issue, but reduces system functionality.

Configuration:
iPhone 7 256GB AT&T, on WiFi

Attachments: