SUNIcolor

How do I use it?

Colors are shown in groups of two, the left showing what the color looks like in light mode and the right in dark mode.
Note: Colors with an alpha component are displayed over a white background and display an "A" when hovered over or clicked on.
Simply click on a color swatch to copy the corresponding UIKit/AppKit/SwiftUI initializer. Use the buttons near the search bar to select one of Swift, SwiftUI or Objective-C.

Where did these colors come from?

The colors are from internal iOS or MacOs frameworks such as ChatKit, SiriUI, and FitnessUI. These color constants are defined by Apple but are private and inaccessible to developers. In addition SUNIcolor includes all public color constants.
Learn more about private frameworks (blog post by Fernando Bunn).

How did you find them?

Using Private Framework header dumps we can see all of the NS/UIColor constants used by Apple. Then using Objective-C’s dynamic runtime we can load these frameworks on device and use “[NSClassFromString(@"UIColor") valueForKey: _selector_ ” to access the color objects.