# CVBufferCopyAttachment(_:_:_:) Returns a copy of an attachment from a Core Video buffer. ``` func CVBufferCopyAttachment(_ buffer: CVBuffer, _ key: CFString, _ attachmentMode: UnsafeMutablePointer?) -> CFTypeRef? ``` ## Parameters `buffer` A buffer with an attachment to copy. `key` A string that identifies the attachment, which can be of any . See [CVBuffer Attachment Keys](/documentation/CoreVideo/cvbuffer-attachment-keys) and [Image Buffer Attachment Keys](/documentation/CoreVideo/image-buffer-attachment-keys) for predefined values. `attachmentMode` On output, this value points to the mode of the attachment. See [`CVAttachmentMode`](/documentation/CoreVideo/CVAttachmentMode) for possible values. This value is if the buffer doesn’t define an attachment mode. ## Return Value The requested attachment, or `nil` if no attachment for the specified key exists. ## Discussion This function returns a retained attachment value, which you need to release when you’re done with it. --- 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)