CupertinoDynamicColor class

A Color subclass that represents a family of colors, and the correct effective color in the color family.

When used as a regular color, CupertinoDynamicColor is equivalent to the effective color (i.e. CupertinoDynamicColor.value will come from the effective color), which is determined by the BuildContext it is last resolved against. If it has never been resolved, the light, normal contrast, base elevation variant CupertinoDynamicColor.color will be the default effective color.

Sometimes manually resolving a CupertinoDynamicColor is not necessary, because the Cupertino Library provides built-in support for it.

Using CupertinoDynamicColor in a Cupertino widget

When a Cupertino widget is provided with a CupertinoDynamicColor, either directly in its constructor, or from an InheritedWidget it depends on (for example, DefaultTextStyle), the widget will automatically resolve the color using CupertinoDynamicColor.resolve against its own BuildContext, on a best-effort basis.

CupertinoButton(
  // CupertinoDynamicColor works out of box in a CupertinoButton.
  color: const CupertinoDynamicColor.withBrightness(
    color: CupertinoColors.white,
    darkColor: CupertinoColors.black,
  ),
  onPressed: () { },
  child: child,
)

Using a CupertinoDynamicColor from a CupertinoTheme

When referring to a CupertinoTheme color, generally the color will already have adapted to the ambient BuildContext, because CupertinoTheme.of implicitly resolves all the colors used in the retrieved CupertinoThemeData, before returning it.

Container(
  // Container is not a Cupertino widget, but CupertinoTheme.of implicitly
  // resolves colors used in the retrieved CupertinoThemeData.
  color: CupertinoTheme.of(context).primaryColor,
)

Manually Resolving a CupertinoDynamicColor

When used to configure a non-Cupertino widget, or wrapped in an object opaque to the receiving Cupertino component, a CupertinoDynamicColor may need to be manually resolved using CupertinoDynamicColor.resolve, before it can used to paint. For example, to use a custom Border in a CupertinoNavigationBar, the colors used in the Border have to be resolved manually before being passed to CupertinoNavigationBar's constructor.

CupertinoNavigationBar(
  // CupertinoNavigationBar does not know how to resolve colors used in
  // a Border class.
  border: Border(
    bottom: BorderSide(
      color: CupertinoDynamicColor.resolve(CupertinoColors.systemBlue, context),
    ),
  ),
)

// ...

Container(
  // Container is not a Cupertino widget.
  color: CupertinoDynamicColor.resolve(CupertinoColors.systemBlue, context),
)

See also:

• CupertinoUserInterfaceLevel, an InheritedWidget that may affect color resolution of a CupertinoDynamicColor.
• CupertinoTheme.of, a static method that retrieves the ambient CupertinoThemeData, and then resolves CupertinoDynamicColors used in the retrieved data.