Swift Package Manager Skill

Dependency management, package creation, and distribution with Swift Package Manager.

Prerequisites

• Swift 5.5+ toolchain
• Xcode 14+ or VS Code with Swift extension
• Git for version control

Parameters

parameters:
  swift_tools_version:
    type: string
    default: "5.9"
  platforms:
    type: array
    items: [iOS, macOS, watchOS, tvOS, visionOS, linux]
    default: [iOS, macOS]
  package_type:
    type: string
    enum: [library, executable, plugin]
    default: library

Topics Covered

Package.swift Structure

Dependency Specification

Target Types

Code Examples

Complete Package.swift

// swift-tools-version: 5.9
import PackageDescription

let package = Package(
    name: "NetworkKit",
    platforms: [
        .iOS(.v15),
        .macOS(.v12),
        .watchOS(.v8),
        .tvOS(.v15)
    ],
    products: [
        .library(
            name: "NetworkKit",
            targets: ["NetworkKit"]
        ),
        .library(
            name: "NetworkKitMocks",
            targets: ["NetworkKitMocks"]
        )
    ],
    dependencies: [
        .package(url: "https://github.com/apple/swift-log.git", from: "1.5.0"),
        .package(url: "https://github.com/apple/swift-collections.git", from: "1.0.0")
    ],
    targets: [
        .target(
            name: "NetworkKit",
            dependencies: [
                .product(name: "Logging", package: "swift-log"),
                .product(name: "OrderedCollections", package: "swift-collections")
            ],
            resources: [
                .process("Resources")
            ],
            swiftSettings: [
                .enableExperimentalFeature("StrictConcurrency")
            ]
        ),
        .target(
            name: "NetworkKitMocks",
            dependencies: ["NetworkKit"]
        ),
        .testTarget(
            name: "NetworkKitTests",
            dependencies: [
                "NetworkKit",
                "NetworkKitMocks"
            ],
            resources: [
                .copy("Fixtures")
            ]
        )
    ]
)

Library with Multiple Targets

// swift-tools-version: 5.9
import PackageDescription

let package = Package(
    name: "FeatureKit",
    platforms: [.iOS(.v16), .macOS(.v13)],
    products: [
        // Main library
        .library(name: "FeatureKit", targets: ["FeatureKit"]),
        // Individual features for selective import
        .library(name: "AuthFeature", targets: ["AuthFeature"]),
        .library(name: "ProfileFeature", targets: ["ProfileFeature"])
    ],
    dependencies: [
        .package(url: "https://github.com/pointfreeco/swift-composable-architecture", from: "1.0.0")
    ],
    targets: [
        // Core shared code
        .target(
            name: "Core",
            dependencies: []
        ),

        // Auth feature
        .target(
            name: "AuthFeature",
            dependencies: [
                "Core",
                .product(name: "ComposableArchitecture", package: "swift-composable-architecture")
            ]
        ),

        // Profile feature
        .target(
            name: "ProfileFeature",
            dependencies: [
                "Core",
                .product(name: "ComposableArchitecture", package: "swift-composable-architecture")
            ]
        ),

        // Umbrella target
        .target(
            name: "FeatureKit",
            dependencies: ["AuthFeature", "ProfileFeature"]
        ),

        // Tests
        .testTarget(
            name: "AuthFeatureTests",
            dependencies: ["AuthFeature"]
        ),
        .testTarget(
            name: "ProfileFeatureTests",
            dependencies: ["ProfileFeature"]
        )
    ]
)

Command-Line Tool

// swift-tools-version: 5.9
import PackageDescription

let package = Package(
    name: "swift-format-tool",
    platforms: [.macOS(.v13)],
    products: [
        .executable(name: "swift-format-tool", targets: ["swift-format-tool"])
    ],
    dependencies: [
        .package(url: "https://github.com/apple/swift-argument-parser", from: "1.2.0"),
        .package(url: "https://github.com/apple/swift-syntax", from: "509.0.0")
    ],
    targets: [
        .executableTarget(
            name: "swift-format-tool",
            dependencies: [
                .product(name: "ArgumentParser", package: "swift-argument-parser"),
                .product(name: "SwiftSyntax", package: "swift-syntax"),
                .product(name: "SwiftParser", package: "swift-syntax")
            ]
        )
    ]
)

Local Development Package

// In your app's Package.swift or Xcode project
// Use local path during development

// Package.swift with local override
let package = Package(
    name: "MyApp",
    dependencies: [
        // Production: Use remote
        // .package(url: "https://github.com/company/SharedKit", from: "1.0.0")

        // Development: Use local
        .package(path: "../SharedKit")
    ],
    targets: [
        .target(name: "MyApp", dependencies: ["SharedKit"])
    ]
)

Swift Macro Package

// swift-tools-version: 5.9
import PackageDescription
import CompilerPluginSupport

let package = Package(
    name: "MacroKit",
    platforms: [.macOS(.v10_15), .iOS(.v13)],
    products: [
        .library(name: "MacroKit", targets: ["MacroKit"])
    ],
    dependencies: [
        .package(url: "https://github.com/apple/swift-syntax", from: "509.0.0")
    ],
    targets: [
        // Macro implementation
        .macro(
            name: "MacroKitMacros",
            dependencies: [
                .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
                .product(name: "SwiftCompilerPlugin", package: "swift-syntax")
            ]
        ),

        // Library that exposes the macro
        .target(
            name: "MacroKit",
            dependencies: ["MacroKitMacros"]
        ),

        // Tests for the macro
        .testTarget(
            name: "MacroKitTests",
            dependencies: [
                "MacroKitMacros",
                .product(name: "SwiftSyntaxMacrosTestSupport", package: "swift-syntax")
            ]
        )
    ]
)

CLI Commands

# Create new package
swift package init --type library
swift package init --type executable
swift package init --type macro

# Build
swift build
swift build -c release

# Test
swift test
swift test --filter MyTests

# Update dependencies
swift package update
swift package update PackageName

# Resolve dependencies
swift package resolve

# Show dependencies
swift package show-dependencies
swift package show-dependencies --format json

# Generate Xcode project (deprecated but useful)
swift package generate-xcodeproj

# Clean
swift package clean
swift package reset

# Dump package description
swift package dump-package

Troubleshooting

Common Issues

Debug Tips

# Verbose build
swift build -v

# Check resolved versions
cat Package.resolved

# Dependency tree
swift package show-dependencies --format dot | dot -Tpng -o deps.png

# Rebuild from scratch
rm -rf .build Package.resolved
swift package resolve
swift build

Validation Rules

validation:
  - rule: pin_versions
    severity: warning
    check: Use version ranges, not branch/revision in production
  - rule: semantic_versioning
    severity: error
    check: Follow semver for your packages
  - rule: platform_support
    severity: info
    check: Declare minimum platform versions

Usage

Skill("swift-spm")

Related Skills

• swift-fundamentals - Language basics
• swift-testing - Package testing
• swift-architecture - Package design