---
title: Compressing file system directories
framework: accelerate
role: article
role_heading: Article
path: accelerate/compressing-file-system-directories
---

# Compressing file system directories

Compress the contents of an entire directory and store the result on the file system.

## Overview

Overview In this article, you’ll learn how to use AppleArchive to compress the contents of an entire directory to a single archive file. The code below compresses the contents of a directory name src using the Algorithm.lzfse algorithm, and stores the result in a file named directory.aar. Create the file stream to write the compressed file Use fileStream(path:mode:options:permissions:) to create the file stream that writes the compressed file to the file system. In this case, use the writeOnly mode: let archiveDestination = NSTemporaryDirectory() + "directory.aar" let archiveFilePath = FilePath(archiveDestination)

guard let writeFileStream = ArchiveByteStream.fileStream(         path: archiveFilePath,         mode: .writeOnly,         options: [ .create ],         permissions: FilePermissions(rawValue: 0o644)) else {     return } defer {     try? writeFileStream.close() } Create the compression stream Create the compression stream, and specify the compression algorithm as lzfse. Specify the file-writing stream as the stream that receives the compressed data: guard let compressStream = ArchiveByteStream.compressionStream(         using: .lzfse,         writingTo: writeFileStream) else {     return } defer {     try? compressStream.close() } Create the encoding stream Create the encoding stream. The encoding stream encodes its data as a byte stream, and sends the encoded data to the compression stream: guard let encodeStream = ArchiveStream.encodeStream(writingTo: compressStream) else {     return } defer {     try? encodeStream.close() } Define the header keys Create a field key set that defines the fields in the archive header: guard let keySet = ArchiveHeader.FieldKeySet("TYP,PAT,LNK,DEV,DAT,UID,GID,MOD,FLG,MTM,BTM,CTM") else {     return } For more information about three-letter keys, see init(_:). Compress the directory contents Use writeDirectoryContents(archiveFrom:path:keySet:selectUsing:flags:threadCount:) to write the directory contents to the encode stream. In turn, the encode stream writes to the compression stream and then, the compression stream writes to the file stream. Finally, the file stream writes the archive file to the file system: let sourcePath = NSTemporaryDirectory() + "src/" let source = FilePath(sourcePath)

do {     try encodeStream.writeDirectoryContents(         archiveFrom: source,         keySet: keySet) } catch {     fatalError("Write directory contents failed.") } On return, directory.aar exists in NSTemporaryDirectory() and contains the compressed contents of src/.

## See Also

### Directories, Files, and Data Archives

- [Compressing single files](accelerate/compressing-single-files.md)
- [Decompressing single files](accelerate/decompressing-single-files.md)
- [Decompressing and extracting an archived directory](accelerate/decompressing-and-extracting-an-archived-directory.md)
- [Compressing and saving a string to the file system](accelerate/compressing-and-saving-a-string-to-the-file-system.md)
- [Decompressing and parsing an archived string](accelerate/decompressing-and-parsing-an-archived-string.md)