# withCompressionStream(appendingTo:flags:threadCount:_:) Reopens a compression sequential output stream and calls the given closure. ``` static func withCompressionStream(appendingTo compressedStream: ArchiveByteStream, flags: ArchiveFlags = [], threadCount: Int = 0, _ body: (ArchiveByteStream) throws -> E) throws -> E ``` ## Parameters `compressedStream` The output stream that the function reopens and receives the compressed data. `flags` Flags that control the behavior of the operation. `threadCount` The number of worker threads that the operation uses, set to `0` for default. `body` A closure with the archive byte stream passed as a parameter. ## Return Value The result of the closure. ## Discussion This function opens a stream created by [`compressionStream(appendingTo:flags:threadCount:)`](/documentation/AppleArchive/ArchiveByteStream/compressionStream(appendingTo:flags:threadCount:)), calls the specified closure, and closes the stream. --- 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)