# @ohos.app.ability.UIExtensionAbility (Base Class for ExtensionAbilities with UI)

<!--Kit: Ability Kit-->
<!--Subsystem: Ability-->
<!--Owner: @zhangyafei-echo; @xuzhihao666-->
<!--Designer: @zhangyafei-echo-->
<!--Tester: @lixueqing513-->
<!--Adviser: @huipeizi-->

UIExtensionAbility is a base class for ExtensionAbilities with UI in specific scenarios. It provides properties and APIs related to ExtensionAbilities with UI. It inherits from [ExtensionAbility](js-apis-app-ability-extensionAbility.md). You cannot inherit from this base class. For details about the inheritance relationship of each ability, see [Inheritance Relationship](./js-apis-app-ability-ability.md#ability-inheritance-relationship).

> **NOTE**
>
> The initial APIs of this module are supported since API version 10. Newly added APIs will be marked with a superscript to indicate their earliest API version.
>
> The APIs of this module can be used only in the stage model.

## Modules to Import

```ts
import { UIExtensionAbility } from '@kit.AbilityKit';
```

## UIExtensionAbility

Base class for ExtensionAbilities that has a UI, designed for specific scenarios. It introduces properties and methods associated with UIExtensionAbilities.

### Properties

**System capability**: SystemCapability.Ability.AbilityRuntime.AbilityCore

| Name| Type| Read-only| Optional| Description|
| -------- | -------- | -------- | -------- | -------- |
| context | [UIExtensionContext](js-apis-inner-application-uiExtensionContext.md) | No| No| Context of the UIExtensionAbility.|

### onCreate

onCreate(launchParam: AbilityConstant.LaunchParam): void

Called to initialize the service logic when a UIExtensionAbility is being created.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| launchParam<sup>12+</sup> | [AbilityConstant.LaunchParam](js-apis-app-ability-abilityConstant.md#launchparam) | Yes| Parameters for starting the UIExtensionAbility, and the reason for the last abnormal exit.|

**Example**

```ts
// The UIExtensionAbility class does not allow direct inheritance by third-party applications. The child class ShareExtensionAbility is used here as an example.
import { ShareExtensionAbility, AbilityConstant } from '@kit.AbilityKit';

const TAG: string = '[testTag] ShareExtAbility';

export default class ShareExtAbility extends ShareExtensionAbility {
  onCreate(launchParam: AbilityConstant.LaunchParam) {
    console.info(TAG, `onCreate, launchParam: ${JSON.stringify(launchParam)}`);
  }
}
```

### onSessionCreate

onSessionCreate(want: Want, session: UIExtensionContentSession): void

Called when a UIExtensionContentSession instance is created for this UIExtensionAbility.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| want | [Want](js-apis-app-ability-want.md) | Yes| Want information related to this UIExtensionAbility, including the ability name and bundle name.|
| session | [UIExtensionContentSession](js-apis-app-ability-uiExtensionContentSession.md) | Yes| UI content information related to this UIExtensionAbility.|

**Example**

```ts
// The UIExtensionAbility class does not allow direct inheritance by third-party applications. The child class ShareExtensionAbility is used here as an example.
import { ShareExtensionAbility, UIExtensionContentSession, Want } from '@kit.AbilityKit';

const TAG: string = '[testTag] ShareExtAbility';

export default class ShareExtAbility extends ShareExtensionAbility {
  onSessionCreate(want: Want, session: UIExtensionContentSession) {
    console.info(TAG, `onSessionCreate, want: ${JSON.stringify(want)}`);
  }
}
```

### onSessionDestroy

onSessionDestroy(session: UIExtensionContentSession): void

Called when a UIExtensionContentSession instance is destroyed for this UIExtensionAbility.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| session | [UIExtensionContentSession](js-apis-app-ability-uiExtensionContentSession.md) | Yes| UI content information related to this UIExtensionAbility.|

**Example**

```ts
// The UIExtensionAbility class does not allow direct inheritance by third-party applications. The child class ShareExtensionAbility is used here as an example.
import { ShareExtensionAbility, UIExtensionContentSession } from '@kit.AbilityKit';

const TAG: string = '[testTag] ShareExtAbility';

export default class ShareExtAbility extends ShareExtensionAbility {
  onSessionDestroy(session: UIExtensionContentSession) {
    console.info(TAG, `onSessionDestroy`);
  }
}
```

### onForeground

onForeground(): void

Called when this UIExtensionAbility is switched from the background to the foreground.

**System capability**: SystemCapability.Ability.AbilityRuntime.AbilityCore

**Example**

```ts
// The UIExtensionAbility class does not allow direct inheritance by third-party applications. The child class ShareExtensionAbility is used here as an example.
import { ShareExtensionAbility } from '@kit.AbilityKit';

const TAG: string = '[testTag] ShareExtAbility';

export default class ShareExtAbility extends ShareExtensionAbility {
  onForeground() {
    console.info(TAG, `onForeground`);
  }
}
```

### onBackground

onBackground(): void

Called when this UIExtensionAbility is switched from the foreground to the background.

**System capability**: SystemCapability.Ability.AbilityRuntime.AbilityCore

**Example**

```ts
// The UIExtensionAbility class does not allow direct inheritance by third-party applications. The child class ShareExtensionAbility is used here as an example.
import { ShareExtensionAbility } from '@kit.AbilityKit';

const TAG: string = '[testTag] ShareExtAbility';

export default class ShareExtAbility extends ShareExtensionAbility {
  onBackground() {
    console.info(TAG, `onBackground`);
  }
}
```

### onDestroy

onDestroy(): void | Promise&lt;void&gt;

Called to clear resources when this UIExtensionAbility is destroyed.
After the **onDestroy()** lifecycle callback is executed, the application may exit. Consequently, the asynchronous function (for example, asynchronously writing data to the database) in **onDestroy()** may fail to be executed. You can use the asynchronous lifecycle to ensure that the subsequent lifecycle continues only after the asynchronous function in **onDestroy()** finishes the execution.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Returns**

| Type             | Description                                                        |
| ----------------- | ------------------------------------------------------------ |
| void \| Promise\<void> | No return value or a Promise object that returns no value.                           |

**Example**

```ts
// The UIExtensionAbility class does not allow direct inheritance by third-party applications. The child class ShareExtensionAbility is used here as an example.
import { ShareExtensionAbility } from '@kit.AbilityKit';

const TAG: string = '[testTag] ShareExtAbility';

export default class ShareExtAbility extends ShareExtensionAbility {
  onDestroy() {
    console.info(TAG, `onDestroy`);
  }
}
```