Update docs against 16170

Signed-off-by: wusongqing<wusongqing@huawei.com>

en/application-dev/reference/apis/Readme-EN.md

@@ -172,6 +172,7 @@
   - [@ohos.promptAction (Prompt)](js-apis-promptAction.md)
   - [@ohos.router (Page Routing)](js-apis-router.md)
   - [@ohos.measure (Text Measurement)](js-apis-measure.md)
+  - [@ohos.uiAppearance (UI Appearance)](js-apis-uiappearance.md)
 
 - Graphics 
   - [@ohos.animation.windowAnimationManager (Window Animation Management)](js-apis-windowAnimationManager.md)

en/application-dev/reference/apis/js-apis-uiappearance.md

+# UI Appearance
+
+The **uiAppearance** module provides basic capabilities for managing the system appearance. It allows for color mode configuration currently, and will introduce more features over time.
+
+> **NOTE**
+>
+> The APIs of this module are supported since API version 9. Updates will be marked with a superscript to indicate their earliest API version.
+>
+> The APIs provided by this module are system APIs.
+
+
+## Modules to Import
+
+```ts
+import uiAppearance from '@ohos.uiAppearance'
+```
+
+
+## DarkMode
+
+Enumerates the color modes.
+
+
+**System capability**: SystemCapability.ArkUI.UiAppearance
+
+| Name| Value| Description|
+| -- | -- | -- |
+| ALWAYS_DARK | 0 | The system is always in dark mode. |
+| ALWAYS_LIGHT | 1 | The system is always in light mode.|
+
+
+## uiAppearance.setDarkMode
+
+setDarkMode(mode: DarkMode, callback: AsyncCallback\<void>): void
+
+Sets the system color mode. This API uses an asynchronous callback to return the result.
+
+**Permission required**: ohos.permission.UPDATE_CONFIGURATION
+
+**System capability**: SystemCapability.ArkUI.UiAppearance
+
+**Parameters**
+| Name| Type| Mandatory| Description|
+| -- | -- | -- | -- |
+| mode | [DarkMode](#darkmode) | Yes| Color mode to set.|
+| callback | AsyncCallback\<void>| Yes| Callback used to return the result.|
+
+**Example**
+  ```ts
+uiAppearance.setDarkMode(uiAppearance.DarkMode.ALWAYS_DARK, (err) => {
+  console.info(`${err}`);
+})
+  ```
+
+
+## uiAppearance.setDarkMode
+
+setDarkMode(mode: DarkMode): Promise\<void>;
+
+Sets the system color mode. This API uses a promise to return the result.
+
+**Permission required**: ohos.permission.UPDATE_CONFIGURATION
+
+**System capability**: SystemCapability.ArkUI.UiAppearance
+
+**Parameters**
+| Name| Type| Mandatory| Description|
+| -- | -- | -- | -- |
+| mode | [DarkMode](#darkmode) | Yes| Color mode to set.|
+
+**Return value**
+
+| Type  | Description                          |
+| ------ | ------------------------------ |
+| Promise\<void> | Promise that returns no value.|
+
+**Example**
+  ```ts
+uiAppearance.setDarkMode(uiAppearance.DarkMode.ALWAYS_DARK).then(() => {
+    console.log('Set dark-mode successfully.');
+}).catch((err) => {
+    console.log(`Set dark-mode failed, ${err}`);
+});
+  ```
+
+
+## uiAppearance.getDarkMode
+
+getDarkMode(): DarkMode;
+
+Obtains the system color mode.
+
+**Permission required**: ohos.permission.UPDATE_CONFIGURATION
+
+**System capability**: SystemCapability.ArkUI.UiAppearance
+
+**Return value**
+| Type| Description|
+| -- | -- |
+|[DarkMode](#darkmode) | Color mode obtained.|
+
+**Example**
+  ```ts
+let darkMode = uiAppearance.getDarkMode();
+console.log(`Get dark-mode ${darkMode}`);
+  ```