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# App Extension Support

Manage the interaction between an app extension and its hosting app.

## Topics

### Extension Support

[`NSExtensionRequestHandling`](/documentation/Foundation/NSExtensionRequestHandling)

The interface an app extension uses to respond to a request from a host app.

[`NSExtensionContext`](/documentation/Foundation/NSExtensionContext)

The host app context from which an app extension is invoked.

### Share Extensions

[Supporting suggestions in your app’s share extension](/documentation/Foundation/supporting-suggestions-in-your-app-s-share-extension)

Make your messaging app available for share sheet suggestions and use SiriKit intents to populate your app’s share extension.

### Attachments

[`NSItemProvider`](/documentation/Foundation/NSItemProvider)

An item provider for conveying data or a file between processes during drag-and-drop or copy-and-paste activities, or from a host app to an app extension.

[`NSExtensionItem`](/documentation/Foundation/NSExtensionItem)

An immutable collection of values representing different aspects of an item for an extension to act upon.

  <doc://com.apple.documentation/documentation/AppKit/add-functionality-to-finder-with-action-extensions>

### Host App Interaction

[`NSUserActivity`](/documentation/Foundation/NSUserActivity)

A representation of the state of your app at a moment in time.

[`NSUserActivityDelegate`](/documentation/Foundation/NSUserActivityDelegate)

The interface through which a user activity instance notifies its delegate of updates.


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