VoiceOver : is 'accessibilityActivationPoint' really useful?

Question

I tried and understood what could be the purpose of the accessibilityActivationPoint but in vain. When a focused accessible element is activated, that property should indicate VoiceOver the specific area it's going to activate when a user double-taps the element (Apple reference) : for me, it's always the selected element itself.

I understood the selected element is considered as a block by VoiceOver, whatever the other elements inside. Once a double tap occurs to activate this block, VoiceOver calls accessibilityActivate to know what to perform (Apple reference).

1/. I've written many tests by creating a custom view including a switch control. Whatever the value of accessibilityActivationPoint inside (or outside on another switch control), the value of the switch control never changes. Is it a proper use case or am I totally wrong ?

2/. When we gather many elements inside one accessible element, how is VoiceOver able to activate one of them while they aren't accessible by definition ? Pointing one of them thanks to the accessibilityActivationPoint should work ?

Personally, I couldn't make it work and think that I'm really confusing accessibilityActivationPoint and accessibilityActivate.

Any help would be appreciated, thanks in advance.

Answer 1

Yes, you have the right idea with accessibilityActivate and accessibilityActivationPoint. Note that, in order for it to work, the accessibilityActivationPoint needs to be a point within the Control that you are trying to activate in on-screen coordinates (use the convert function!).

I think the short answer is "yes" to answer your second question, but, just to clear up confusion about when Accessibility Activation Point is useful, I'll go into more detail about it.

By default (aka, the default behavior for AcessibilityActivate()), when any view is activated by VoiceOver, VoiceOver will send a "tap gesture" to the center of the view. The position of this "tap gesture" can be changed by updating the accessibilityActivationPoint attribute on a view. Below, I have an example for how this property can be used.

Let's say you have a blank button (in the image below, the button is the gray box) next to some text:

For the purpose of accessibility, you may want to make the entire view that holds the button and text an Accessibility Element (so that VoiceOver users can easily understand that the button is associated with the text "Worldspace Attest"). In the image below, I am using Accessibility Inspector to show that the view holding both of these elements is an Accessibility Element.

Notice in these images that the button is not in the center of the view, but rather, it is to the right. When you activate this view using VoiceOver, the view will not select the button; instead, it will send a "tap" to the center of the view (which is the same as tapping the text, which does not do anything). In order to select the button, you have to set the view's accessibilityActivationPoint to be the on-screen coordinates of the button:

view.accessibilityActivationPoint = self.convert(button.center, to: UIApplication.shared.windows.first)

This should make it so that this button is usable by a VoiceOver user.

I hope this information clears up any confusion about the Accessibility Activation Point property. The example I used above can be found in this repository in the "Active Control Name" demo.