Accessible colors for DynamicColorIOS (#31651)

Summary:
Allow you to harvest the `UIAccessibilityContrastHigh` trait from iOS to show accessible colors when high contrast mode is enabled.

```jsx
// usage

PlatformColorIOS({
  light: '#eeeeee',
  dark: '#333333',
  highContrastLight: '#ffffff',
  highContrastDark: '#000000',
});

// {
//   "dynamic": {
//     "light": "#eeeeee",
//     "dark": "#333333",
//     "highContrastLight": "#ffffff",
//     "highContrastDark": "#000000",
//   }
// }
```

This is how apple's own dynamic system colors work under the hood (https://developer.apple.com/design/human-interface-guidelines/ios/visual-design/color/#dynamic-system-colors)

 ---

The react native docs mention that more keys may become available in the future, which this PR is adding:

> In the future, more keys might become available for different user preferences, like high contrast.

https://reactnative.dev/docs/dynamiccolorios

## Changelog

<!-- Help reviewers and the release process by writing your own changelog entry. For an example, see:
https://github.com/facebook/react-native/wiki/Changelog
-->

[iOS] [Added] - High contrast dynamic color options for dark and light mode.

Pull Request resolved: #31651

Test Plan: Added unit tests for `normalizeColor` to pass the high contrast colors downstream to RCTConvert

Reviewed By: lunaleaps

Differential Revision: D28922536

Pulled By: p-sun

fbshipit-source-id: f81417f003c3adefac50e994e62b9be14ffa91a1

Libraries/StyleSheet/PlatformColorValueTypes.ios.js

@@ -16,6 +16,8 @@ export opaque type NativeColorValue = {
   dynamic?: {
     light: ?(ColorValue | ProcessedColorValue),
     dark: ?(ColorValue | ProcessedColorValue),
+    highContrastLight?: ?(ColorValue | ProcessedColorValue),
+    highContrastDark?: ?(ColorValue | ProcessedColorValue),
   },
 };
 
@@ -26,12 +28,21 @@ export const PlatformColor = (...names: Array<string>): ColorValue => {
 export type DynamicColorIOSTuplePrivate = {
   light: ColorValue,
   dark: ColorValue,
+  highContrastLight?: ColorValue,
+  highContrastDark?: ColorValue,
 };
 
 export const DynamicColorIOSPrivate = (
   tuple: DynamicColorIOSTuplePrivate,
 ): ColorValue => {
-  return {dynamic: {light: tuple.light, dark: tuple.dark}};
+  return {
+    dynamic: {
+      light: tuple.light,
+      dark: tuple.dark,
+      highContrastLight: tuple.highContrastLight,
+      highContrastDark: tuple.highContrastDark,
+    },
+  };
 };
 
 export const normalizeColorObject = (
@@ -49,6 +60,8 @@ export const normalizeColorObject = (
       dynamic: {
         light: normalizeColor(dynamic.light),
         dark: normalizeColor(dynamic.dark),
+        highContrastLight: normalizeColor(dynamic.highContrastLight),
+        highContrastDark: normalizeColor(dynamic.highContrastDark),
       },
     };
     return dynamicColor;
@@ -67,6 +80,8 @@ export const processColorObject = (
       dynamic: {
         light: processColor(dynamic.light),
         dark: processColor(dynamic.dark),
+        highContrastLight: processColor(dynamic.highContrastLight),
+        highContrastDark: processColor(dynamic.highContrastDark),
       },
     };
     return dynamicColor;

Libraries/StyleSheet/PlatformColorValueTypesIOS.ios.js

@@ -14,8 +14,15 @@ import {DynamicColorIOSPrivate} from './PlatformColorValueTypes';
 export type DynamicColorIOSTuple = {
   light: ColorValue,
   dark: ColorValue,
+  highContrastLight?: ColorValue,
+  highContrastDark?: ColorValue,
 };
 
 export const DynamicColorIOS = (tuple: DynamicColorIOSTuple): ColorValue => {
-  return DynamicColorIOSPrivate({light: tuple.light, dark: tuple.dark});
+  return DynamicColorIOSPrivate({
+    light: tuple.light,
+    dark: tuple.dark,
+    highContrastLight: tuple.highContrastLight,
+    highContrastDark: tuple.highContrastDark,
+  });
 };

Libraries/StyleSheet/PlatformColorValueTypesIOS.js

@@ -13,6 +13,8 @@ import type {ColorValue} from './StyleSheet';
 export type DynamicColorIOSTuple = {
   light: ColorValue,
   dark: ColorValue,
+  highContrastLight?: ColorValue,
+  highContrastDark?: ColorValue,
 };
 
 export const DynamicColorIOS = (tuple: DynamicColorIOSTuple): ColorValue => {

Libraries/StyleSheet/__tests__/normalizeColor-test.js

@@ -43,6 +43,25 @@ describe('iOS', () => {
       expect(normalizedColor).toEqual(expectedColor);
     });
 
+    it('should normalize iOS Dynamic colors with accessible colors', () => {
+      const color = DynamicColorIOS({
+        light: 'black',
+        dark: 'white',
+        highContrastLight: 'red',
+        highContrastDark: 'blue',
+      });
+      const normalizedColor = normalizeColor(color);
+      const expectedColor = {
+        dynamic: {
+          light: 'black',
+          dark: 'white',
+          highContrastLight: 'red',
+          highContrastDark: 'blue',
+        },
+      };
+      expect(normalizedColor).toEqual(expectedColor);
+    });
+
     it('should normalize iOS Dynamic colors with PlatformColor colors', () => {
       const color = DynamicColorIOS({
         light: PlatformColor('systemBlackColor'),

React/Base/RCTConvert.m

@@ -879,13 +879,29 @@ + (UIColor *)UIColor:(id)json
       UIColor *lightColor = [RCTConvert UIColor:light];
       id dark = [appearances objectForKey:@"dark"];
       UIColor *darkColor = [RCTConvert UIColor:dark];
+      id highContrastLight = [appearances objectForKey:@"highContrastLight"];
+      UIColor *highContrastLightColor = [RCTConvert UIColor:highContrastLight];
+      id highContrastDark = [appearances objectForKey:@"highContrastDark"];
+      UIColor *highContrastDarkColor = [RCTConvert UIColor:highContrastDark];
       if (lightColor != nil && darkColor != nil) {
 #if defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 130000
         if (@available(iOS 13.0, *)) {
-          UIColor *color =
-              [UIColor colorWithDynamicProvider:^UIColor *_Nonnull(UITraitCollection *_Nonnull collection) {
-                return collection.userInterfaceStyle == UIUserInterfaceStyleDark ? darkColor : lightColor;
-              }];
+          UIColor *color = [UIColor colorWithDynamicProvider:^UIColor *_Nonnull(
+                                        UITraitCollection *_Nonnull collection) {
+            if (collection.userInterfaceStyle == UIUserInterfaceStyleDark) {
+              if (collection.accessibilityContrast == UIAccessibilityContrastHigh && highContrastDarkColor != nil) {
+                return highContrastDarkColor;
+              } else {
+                return darkColor;
+              }
+            } else {
+              if (collection.accessibilityContrast == UIAccessibilityContrastHigh && highContrastLightColor != nil) {
+                return highContrastLightColor;
+              } else {
+                return lightColor;
+              }
+            }
+          }];
           return color;
         } else {
 #endif

packages/eslint-plugin-react-native-community/platform-colors.js

@@ -60,7 +60,6 @@ module.exports = {
           const properties = args[0].properties;
           if (
             !(
-              properties.length === 2 &&
               properties[0].type === 'Property' &&
               properties[0].key.name === 'light' &&
               properties[1].type === 'Property' &&