# append(bufferReference:flags:) Adds a reference to another block buffer. ``` func append(bufferReference: T, flags: CMBlockBuffer.Flags = []) throws where T : CMBlockBufferProtocol ``` ## Parameters `bufferReference` A block buffer to refer to. The buffer must not be empty unless you also pass the [`permitEmptyReference`](/documentation/CoreMedia/CMBlockBuffer/Flags/permitEmptyReference) flag. `flags` Feature and control flags. --- 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)