Working with ZIP/archives in Swift (iOS/macOS): A Complete Guide

Working with ZIP/archives in Swift (iOS/macOS)

In modern iOS and macOS development, there is often a need to compress files into ZIP archives or extract data from them. This may be necessary for saving space, transferring data over a network, or organizing backups. In this article, we will look at two main approaches: using the built-in capabilities of Foundation and the popular third-party library ZipFoundation.

Built-in Foundation Tools (NSFileCoordinator + Low-Level Work)

Apple does not provide a high-level API for working with ZIP in Foundation. However, starting with iOS 12 / macOS 10.14, it became possible to use NSFileCoordinator and NSFileWrapper for some operations. But for full-fledged work with ZIP, the system utility libz is most often used via the C interface.

Example: Compressing data with libz

import Compressionimport Foundation

func compressData(_ data: Data) -> Data? {    let sourceData = data as NSData    let compressedData = NSMutableData(length: data.count)!    var compressedSize = data.count        let result = compression_encode(        compressedData.mutableBytes.assumingMemoryBound(to: UInt8.self),        &compressedSize,        sourceData.bytes.assumingMemoryBound(to: UInt8.self),        data.count,        nil,        COMPRESSION_ZLIB    )        guard result == COMPRESSION_STATUS_OK else { return nil }    compressedData.length = compressedSize    return compressedData as Data}

ZipFoundation Library (Recommended Approach)

ZipFoundation is a lightweight open-source library for working with ZIP archives in Swift. It supports iOS, macOS, tvOS, and watchOS. Installation via Swift Package Manager:

// In Package.swift or via Xcodedependencies: [    .package(url: "https://github.com/weichsel/ZIPFoundation.git", from: "0.9.0")]

Key Features of ZipFoundation:

• Creating ZIP archives from files and folders
• Extracting individual files or the entire archive
• Password support (AES-256)
• Streaming support for large files
• Compatibility with macOS and iOS

Example 1: Creating a ZIP Archive

import ZIPFoundationimport Foundation

func createZip(from sourceURL: URL, to destinationURL: URL) throws {    let fileManager = FileManager()        // Create an archive from a folder    try fileManager.zipItem(at: sourceURL, to: destinationURL)        // Or from a single file    // try fileManager.zipItem(at: sourceURL, to: destinationURL,     //     shouldKeepParent: false)}

// Usagelet documents = FileManager.default.urls(for: .documentDirectory,                                           in: .userDomainMask).first!let sourceFolder = documents.appendingPathComponent("MyData")let archiveURL = documents.appendingPathComponent("backup.zip")

do {    try createZip(from: sourceFolder, to: archiveURL)    print("Archive created: \\(archiveURL.path)")} catch {    print("Error: \\(error)")}

Example 2: Extracting a ZIP Archive

import ZIPFoundation

func unzipArchive(at sourceURL: URL, to destinationURL: URL) throws {    let fileManager = FileManager()        // Create the destination folder if it doesn't exist    try fileManager.createDirectory(at: destinationURL,                                      withIntermediateDirectories: true)        // Extract    try fileManager.unzipItem(at: sourceURL, to: destinationURL)}

// Usagelet archiveURL = documents.appendingPathComponent("backup.zip")let extractFolder = documents.appendingPathComponent("ExtractedData")

do {    try unzipArchive(at: archiveURL, to: extractFolder)    print("Extraction complete")} catch {