The .selected accessibility trait indicates when an element has been selected. You’ll notice that VoiceOver announces “selected” before the accessibility label. You can find that in the system for the selected tab in the tab bar, for example.
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Do you have a fancy custom loading animation instead of an UIActivityIndicatorView? You may want to check if it has an accessibility label so a VoiceOver user knows that something is happening. Something like "In progress" or "Loading" could work.
Good accessibility labels are at the core of good accessible apps. It should be a localized succinct string that tells as much as possible about the component (without including its type) and provides context avoiding verbosity and redundancy.
A component can have more than one accessibility trait, they can be combined. A heading can be a button too, for example. Or a button could be selected. You can insert or remove the selected trait to the button, when needed.
