About Accessibility Events
In macOS 10.14.3 and iOS 12.3, the Accessibility Events switch — previously located in Accessibility settings — was unified under the Accessibility Object Model (AOM) control.
How Accessibility Events are used
The new Accessibility Events feature provides a way for web developers to ensure that their custom controls are accessible by users of assistive technology. These actions can now be triggered through assistive technologies like VoiceOver and Switch Control, or through mainstream input devices like keyboards.
Accessibility Events is a subfeature of the Accessibility Object Model (AOM) project, an emerging web technology currently under development as a joint W3C effort by Apple, Google, and the Mozilla Foundation. The draft standard includes new semantic input events, such as increment and decrement actions for custom sliders, dismiss actions for custom dialogs, and paging actions for custom scroll views. The AOM feature is turned off by default in iOS and macOS.
Turn on Accessibility Events
The Accessibility Events feature functions only when the AOM setting is enabled.
To turn on Accessibility Events on your Mac:
Choose Safari > Preferences.
Click Advanced, then select Show Develop Menu in menu bar.
From the Safari menu bar, choose Develop > Experimental Features > Accessibility Object Model.
To turn on Accessibility Events on your iPhone, iPad, or iPod touch:
Go to Settings > Safari > Advanced > Experimental Features.
Tap to turn on Accessibility Object Model.
Apple is committed to accessibility and privacy. The Accessibility Events feature does not allow websites to specifically query whether individuals are using a screen reader or other specific assistive technology, nor does it provide information about a user's ability or disability. However, in order to deliver complex web applications that are compatible with assistive technology actions, web developers might become aware that some form of assistive technology is active on a device — but only when the user tries to operate one of these custom controls.
Apple is actively involved in standards body groups such as the W3C, and we work to design all of our products with privacy in mind. As the standard evolves, we'll continue to evaluate how to best support accessibility on the web with user control.