# writeAll(toAbsoluteOffset:_:) Writes a sequence of bytes to the given offset. ``` @discardableResult func writeAll(toAbsoluteOffset offset: Int64, _ sequence: S) throws -> Int where S : Sequence, S.Element == UInt8 ``` ## Parameters `offset` The file offset where writing begins. `sequence` The bytes to write. ## Return Value The number of bytes written, equal to the number of elements in `sequence`. ## Discussion This method either writes the entire contents of `sequence`, or throws an error if only part of the content was written. Unlike [`writeAll(_:)`](/documentation/System/FileDescriptor/writeAll(_:)), this method preserves the file descriptor’s existing offset. If `sequence` doesn’t implement the method, temporary space will be allocated as needed. --- 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)