# update(data:) Updates the message authentication code computation with a block of data. ``` mutating func update(data: D) where D : DataProtocol ``` ## Parameters `data` The data for which to compute the authentication code. --- 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)