There is a Color Contrast Calculator conveniently built into the Accessibility Inspector. Find it in Window, in the top menu. Select two colors for text and background and check if it passes for all text sizes or just some of the largest ones.
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If you are using SwiftUI to build your apps, there is a fairly basic but very useful Accessibility Inspector built right there in the Inspectors Panel, on the right side of Xcode.
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.
Color contrast between text and background is very important for perceivability. As colors come closer to each other, they’re more difficult to distinguish. Notice that colors that work well with big font sizes may not for smaller text.
