iOS 11 triggers UISwitch value change action when `on` attribute is changed within the action handler (11b3 15A5318g)

Number:rdar://33453656 Date Originated:July 21 2017
Status:Open Resolved:
Product:iOS + SDK Product Version:11.0b3 (15A5318g)
Classification:Serious Bug Reproducible:Always

When the UISwitch action handler for ValueChanged changes its own `on` property it triggers the action again which is not expected since iPhone OS 2 and it is exactly against what is documented. The problem isn't observed when the property is changed outside the ValueChanged action.

Steps to Reproduce:
1 - Open the attached project (SwitchTargetActionValue)

2 - Using iOS 10, 9, 8...: touch the switch and observe "Changes: 1" (the action is triggered once, as it expected).

3 - Using iOS 11.0b3 (15A5318g): touch the switch and observe "Changes: 2" (the action is triggered twice, which is a problem)

4 - Notice the behavior isn't observed then "Change" (button) changes the `on` property.

Expected Results:

"Setting the switch to either position does not result in an action message being sent."

Observed Results:
Exactly the opposite of "Setting the switch to either position does not result in an action message being sent.".

When the `on` property is changed within the ValueChanged action it is triggering the action changing a pretty old behavior.

11.0b3 (15A5318g)




The bug is still present in iOS 12.

By tomekwsrod at Feb. 1, 2019, 4:47 p.m. (reply...)

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