There is another accessibility trait: .playsSound, that does a similar thing than .startsMediaSession. This one seems more suitable for buttons that have their own sound effects when interacting with them, like it often happens in games.
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When interacting with a button with VoiceOver, the accessibility label is repeated to the user. If you are playing some audio, it could be difficult to listen to it properly. To avoid that, you can add the .startsMediaSession accessibility trait.

Make sure you support Dynamic Type up to the largest text size available. Take into account that there are five extra accessibility sizes available from the Accessibility Settings. It can make a huge difference for lots of users.

Sometimes we may fail to convey to the user of things changing on the screen in a perceivable way. Toasts and similar should be announced. We may want to make clear that some content on the screen changed. Or we might want to update on progress.
Content © Daniel Devesa Derksen-Staats on Accessibility up to 11! is licensed under CC BY 4.0. License details