# Attachable Implementations ## Topics ### Instance Methods [`func withUnsafeBytes(for: borrowing Attachment, (UnsafeRawBufferPointer) throws -> R) throws -> R`](/documentation/Swift/Substring/withUnsafeBytes(for:_:)) --- 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)