Zoom lets the user magnify the screen if the user needs to zoom in a region to be able to see any details a bit closer. It is useful to know the gestures that let you zoom in, back out, move around the screen, adjust zoom level or show its menu.
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I used to think of Zoom as an accessibility feature that didn't need support from developers. But actually, testing with Zoom might unveil some issues and bad practices. Watch out for buttons that change something far away on the screen. Using a snackbar is usually not a good idea. Especially if it lets you do/undo something. Because they're ephemeral, they're difficult to spot and/or reach with Zoom, VoiceOver, Switch, Keyboard... Confirming a destructive action with a dialog might be better.
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.
Since iOS 14, you can get a human readable localised name for a UIColor, with a very useful property called accessibilityName, that you can use in accessibility attributes like labels or values. How cool is that? https://developer.apple.com/documentation/uikit/uicolor/accessibilityname
