An accessibility trait is the role of the component. Among other things, it gives the user information on how they can interact (or not) with it. When using VoiceOver, the trait is usually (not always) read after the accessibility label.
At the time of writing this tweet, there are 18 different accessibility traits: https://developer.apple.com/documentation/uikit/uiaccessibilitytraits
Some examples are: button, header, selected, adjustable or not enabled.
Accessibility labels should not contain the type of the control, that's a job for the accessibility trait instead. If you have a button with a label like "Close button" and the ".button" trait, VoiceOver will say: "Close button, button".
Styling a search bar is hard. Lots of developers opt to build their own instead. If you do, remember to add the .searchField accessibility trait. VoiceOver will announce "Search Field" indicating the user that results might change as they type.
If, for some reason, you are creating a button from scratch, instead of relying on UIButton (perhaps you are adding a fancy micro interaction animation?), take into account that you’ll need to configure the button accessibility trait.
Content © Daniel Devesa Derksen-Staats — Accessibility up to 11!
