iOS Question Dynamic dark and light modes

enum UIUserInterfaceStyle: Int {
   case unspecified
   case light
   case dark
}

Dynamic System Colors
In addition to tint colors, iOS also provides semantically defined system colors that automatically adapt to both light and dark modes. A semantic color conveys its purpose rather than its appearance or color values. For example, iOS defines colors for use in background areas and for foreground content, such as labels, separators, and fill.

iOS defines two sets of background colors — system and grouped — each of which contains primary, secondary, and tertiary variants that help you convey a hierarchy of information. In general, use the grouped set of background colors when you have a grouped table view; otherwise, use the system set of background colors. For developer guidance, see UI Element Colors.

With both sets of background colors, you generally use the variants to indicate hierarchy in the following ways:

• Primary for the overall view
• Secondary for grouping content or elements within the overall view
• Tertiary for grouping content or elements within secondary elements

For foreground content, iOS defines the following colors:

Color	Used for	API
Label	A text label that contains primary content.	label
Secondary label	A text label that contains secondary content.	secondaryLabel
Tertiary label	A text label that contains tertiary content.	tertiaryLabel
Quaternary label	A text label that contains quaternary content.	quaternaryLabel
Placeholder text	Placeholder text in controls or text views.	placeholderText
Separator	A separator that allows some underlying content to be visible.	separator
Opaque separator	A separator that doesn't allow any underlying content to be visible.	opaqueSeparator
Link	Text that functions as a link.	link

Don’t redefine the semantic meanings of dynamic system colors. To give people a consistent experience and ensure that your interface looks great in all contexts, use dynamic system colors as intended.

Don't try to replicate dynamic system colors. Dynamic system colors may fluctuate from release to release, based on a variety of environmental variables. Instead of trying to create custom colors that match the system colors, use the dynamic system colors.

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