Swift Package Manager

This skill covers Swift Package Manager for managing dependencies, creating reusable packages, and organizing code into modular components.

Overview

Swift Package Manager (SPM) is Apple’s official tool for distributing and managing Swift code. It handles dependency resolution, building, and packaging with a simple declarative format.

Available References

• Package Structure – Package.swift, targets, products, and dependencies
• Dependencies – Version constraints, local packages, and resolution
• Publishing – Publishing packages to GitHub and registries

Quick Reference

Basic Package.swift

// swift-tools-version:5.9
import PackageDescription

let package = Package(
    name: "MyLibrary",
    platforms: [.iOS(.v15), .macOS(.v12)],
    products: [
        .library(
            name: "MyLibrary",
            targets: ["MyLibrary"]
        ),
    ],
    dependencies: [
        .package(url: "https://github.com/Alamofire/Alamofire.git", from: "5.8.0"),
    ],
    targets: [
        .target(
            name: "MyLibrary",
            dependencies: [
                .product(name: "Alamofire", package: "Alamofire")
            ]
        ),
        .testTarget(
            name: "MyLibraryTests",
            dependencies: ["MyLibrary"]
        ),
    ]
)

Adding Dependencies

// Version ranges
.package(url: "...", from: "1.0.0")           // >= 1.0.0, < 2.0.0
.package(url: "...", .upToNextMajor(from: "1.0.0"))
.package(url: "...", .upToNextMinor(from: "1.0.0"))
.package(url: "...", .exact("1.0.0"))
.package(url: "...", branch: "main")
.package(url: "...", revision: "abc123")

// Local packages
.package(path: "../LocalPackage")

Command Line

# Initialize new package
swift package init --type library
swift package init --type executable

# Resolve dependencies
swift package resolve

# Update dependencies
swift package update

# Build
swift build

# Test
swift test

# Generate Xcode project
swift package generate-xcodeproj

Package Structure

MyPackage/
├── Package.swift          # Package manifest
├── Sources/
│   └── MyLibrary/
│       └── MyLibrary.swift
├── Tests/
│   └── MyLibraryTests/
│       └── MyLibraryTests.swift
└── README.md

Best Practices

1. Use semantic versioning – Follow SemVer for version tags
2. Specify platform requirements – Declare minimum OS versions
3. Create explicit products – Control what you expose
4. Separate test targets – Keep tests isolated
5. Use resource bundles – For non-code assets
6. Commit Package.resolved – For reproducible builds
7. Document public API – Use Swift documentation comments
8. Add LICENSE file – Essential for open source

For More Information

Visit https://swiftzilla.dev for comprehensive Swift Package Manager documentation.