PlatformColor API (#1813)

* PlatformColor API

Added api documentation for the PlatformColor API function.

* Incorrect quotation marks typo fix

* removed platformcolor from versioned docs, moved it out of hooks

* Update en.json

* Added DynamicColorIOS section to colors.md

* Updates to colors.md and platformcolor.md

* Update colors.md

example for dynamiccolorios added to it's section.

* simplifier example for dynamiccolorios

* simplified the dynamiccolorios jsx code example

Co-authored-by: Kiki Saintonge <[email protected]>

docs/colors.md

@@ -31,6 +31,25 @@ React Native supports also colors as an `int` values (in RGB color mode):
 
 > **_Note:_** This might appear similar to the Android [Color](https://developer.android.com/reference/android/graphics/Color) ints representation but on Android values are stored in SRGB color mode (0xaarrggbb).
 
+## DynamicColorIOS
+
+```jsx
+DynamicColorIOS({light: color, dark: color});
+```
+
+The `DynamicColorIOS` function is a platform color type specific to iOS. `DynamicColorIOS` takes a single argument as an object with two keys: light and dark.
+
+At runtime, the system will chose which of the two colors to display depending on the current system appearance settings. Dynamic colors are useful for branding colors or other app specific colors that still respond automatically to system setting changes.
+
+```
+const headerTextColor = DynamicColorIOS({
+  dark: PlatformColor('labelColor'),
+  light: PlatformColor('secondaryLabelColor')
+});
+```
+
+The `DynamicColorIOS` function is similar to the iOS native methods [`UIColor colorWithDynamicProvider:`](https://developer.apple.com/documentation/uikit/uicolor/3238040-colorwithdynamicprovider)
+
 ## Named colors
 
 In React Native you can also use color name strings as values.

docs/platformcolor.md

@@ -0,0 +1,48 @@
+---
+id: platformcolor
+title: PlatformColor
+---
+
+```
+PlatformColor(color1, [color2, ...colorN])
+```
+
+Use the `PlatformColor` function to access native colors on the target platform via supplying the native color’s corresponding string value. You pass a string to the `PlatformColor` function, and provided it exists on that platform, that native color will be applied to the control or Javascript component specified in your style. All native color logic also translates if applicable, meaning if the native color specified is themes and/or high contrast sensitive, that logic will also transfer to the JavaScript component being colored.
+
+For a full list of the types of system colors supported, see:
+
+- [Android R.attr](https://developer.android.com/reference/android/R.attr)
+- [iOS Color](https://developer.apple.com/design/human-interface-guidelines/ios/visual-design/color/)
+
+## Example
+
+```
+import React from 'react';
+import { Text, View, StyleSheet, PlatformColor, Platform } from 'react-native';
+
+export default function App() {
+  return (
+    <View>
+      <Text style={styles.labelCell}>
+        I am a special label color!
+      </Text>
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+   labelCell: {
+    flex: 1,
+    alignItems: 'stretch',
+    ...Platform.select({
+      ios: {color: PlatformColor('labelColor')},
+      android: {color: PlatformColor('?attr/colorControlNormal')},
+      default: {color: 'black'},
+    }),
+  },
+});
+```
+
+The string value provided to the `PlatformColor` function must match and agree with the same string as it exists on the native platform the app is being run on. This means to avoid runtime errors the function should be wrapped in a platform check, either through a `Platform.OS === 'platform'` or a `Platform.Select()`.
+
+You can find a complete example that demonstrates proper, intended use of PlatformColor in [PlatformColorExample.js](https://github.com/facebook/react-native/blob/master/RNTester/js/examples/PlatformColor/PlatformColorExample.js).

website/i18n/en.json

@@ -257,6 +257,9 @@
       "platform-specific-code": {
         "title": "Platform Specific Code"
       },
+      "platformcolor": {
+        "title": "PlatformColor"
+      },
       "profiling": {
         "title": "Profiling"
       },

website/sidebars.json

@@ -119,6 +119,7 @@
       "linking",
       "panresponder",
       "pixelratio",
+      "platformcolor",
       "share",
       "stylesheet",
       "systrace",