# init(key:data:) Creates a new extended attribute structure. ``` init(key: String, data: ContiguousArray) ``` ## Parameters `key` The attribute key. `data` The attribute data. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)