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.
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Custom actions work well with VoiceOver and Switch Control. It is also a way of speeding up navigation, and grouping all actions available for an item in a single place, with Full Keyboard Access. Focus an item and use the shortcut Tab (⇥) + Z.
Some recommendations for improving your accessibility labels: don't add the element type, avoid redundancy and verbosity, localize... @MobileA11y has an excellent blog post on it: https://mobilea11y.com/blog/writing-great-labels/ @jordyn2493 has a great video too: https://developer.apple.com/videos/play/wwdc2019/254/
You can add your Accessibility Shortcuts to Control Centre too. One more quick access point and one more reminder to get you testing often and quickly. How to enable Accessibility shortcuts: https://x.com/dadederk/status/1583519154165800960?s=61&t=_fK9Muzu2MyFEeJLVQZcJg
