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@giginet 2024/10/25
@giginet
Creating Intuitive Developer
Tool in Swift
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Self Introduction
• giginet / Kohki Miki
• X / GitHub : @giginet
• Tokyo 🇯🇵
• Work for LY Corporation(2022~)
• iOS DevOps Engineer for LINE
• iOS Development experience since iOS 4 (2010~)
• ❤ 👾 Gaming
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Agenda and Goals
• Finding the issue
• History of Swift ecosystem
• Practical Examples of Developer tools
• Implement your tool
• Implementation / Testing
• For the more usable tools
• Documentation / Deployment / CI
• Contribute to Community
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My OSS Contribution as a core contributor
fastlane Carthage XcodeGen
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My Recent Work : giginet/Scipio (⭐450)
• A next-generation build tool to generate XCFramework
• Convert Swift Package to XCFramework
• Share prebuilt frameworks among developers
1. Resolve and checkout package
manifest with SwiftPM
2. Scipio generates Xcode Project
from each package
3. Build the projects with xcodebuild
4. xcodebuild generates
XCFramework
How does Scipio work?
Resolve manifests
Fetch packages
Generate Xcode Project
Build XCFrameworks
https://speakerdeck.com/giginet/standardizing-build-system-using-modern-swift-packages-in-line
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giginet/swift-testing-revolutionary (⭐200)
• Convert test cases written in XCTest into swift-testing
• Providing Command Plugin and Xcode GUI
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Finding the issue
History and practical example of developer tools
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Tool Developments
What should I develop?
How to develop?
How to spread?
Why should I publish it?
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History of iOS Developer’s Tools
2014 2019
Prehistoric Period Dawn Period Maturity Period
Swift is released Maturation of Swift ecosystem
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Before Swift era(~2015)
• ObjC is not suitable for tool development
• Most tools were developed in Ruby or other languages
• CocoaPods(2011)
• fastlane(2015)
• danger(2015)
• xcpretty
• xcode-select
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Swift released (2015~2019)
• Some useful tools are available
• Carthage(2015)
• SwiftLint(2015)
• XcodeGen(2017)
• tuist(2018)
• No de-facto standard foundations
• SwiftCLI / Commandant / Commander (argument parser)
• Quick / Nimble / Spectre… (Testing Framework)
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Today : Ecosystem of tools development
• The o
ff i
cial development foundations are available
• Swift Package Manager (2015)
• Xcode Integration (2019)
• swift-syntax(2017)
• swift-argument-parser(2020)
• Package Plugin (2022)
• swift-testing(2023)
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What should we develop?
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Begin to develop for your team!
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Practical Example : line-tools
• In-house tool collections for LINE development
• Implemented many features in Swift
• Build script of dependencies
• Prebuilt tasks
• CI scripts
• linter / formatter
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Example 1 : Building dependencies
• Share XCFrameworks using Remote Server
• Based on Scipio
• Features
• Resolve Swift Packages
• Build XCFramework
• Download XCFrameworks
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Example 2 : Prebuilt Tasks
• Useful wrapper tools of XcodeGen
• Features
• Verify Project Spec and dependencies
• Generate Xcode projects from Project Specs
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Example 3 : CI script
• A tool generates TestPlan on CI for Pull Requests Builder
• Generate Test Plan from Pull Request
fi
le di
ff
s
• Features
• Generate TestPlan by PR di
ff
s
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Example 4 : Extend IDE features
• A linter to warn company rules
• Run custom linter on Xcode
• We can use swift-syntax
• Features
• Lint dependency tree
• Lint coding guidelines
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Benefit of developing tools in Swift
• Ubiquitous Language
• Write complex tasks with a powerful language feature
• Using Swift foundations (e.g. swift-syntax)
• Maintainability
• Testability
• Type Safety
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Implement your tools
Basic techniques to create your tools
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No content
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CI / Testing
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Documentation
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Distribution
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Backward Compatibility
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For useful developer tools
• Various technics
• CI / Tests
• Documentation
• Cross-platform / Multi versioning
• Binary distribution
• These also help for OSS or in-house tool
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Kind of developer tools
• Executable
• Good for any purpose
• Difficult to distribute
• Package Plugin (Introduced from Swift 5.6)
• Build Tools Plugin
• Command Plugin
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Build Tools Plugin
• A mechanism to distribute build hooks via Swift Package ecosystem
• Introduced in Swift 5.6
• Code Generator ( Pre-built hook)
• SwiftGen / openapi-generator / License generator
• Linter / Formatter (Post-built hook)
• SwiftLint / SwiftFormat
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Command Plugin
• Distributing command via Swift Package ecosystem
• Can provide Command Line Interface / Xcode GUI
• Example
• docc-plugin
• swift-testing-revolutionary
• See ”Meet Package Plugins" in WWDC22
• https://developer.apple.com/videos/play/wwdc2022/110359/
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swift-argument-parser
• A first-party library to make Command Line Interface(CLI)
• https://github.com/apple/swift-argument-parser
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import ArgumentParser
@main
struct Repeat: ParsableCommand {
@Flag(help: "Include a counter with each repetition.")
var includeCounter = false
@Option(name: .shortAndLong, help: "The number of times to repeat 'phrase'.")
var count: Int? = nil
@Argument(help: "The phrase to repeat.")
var phrase: String
mutating func run() throws {
let repeatCount = count ?? 2
for i in 1...repeatCount {
if includeCounter {
print("\(i): \(phrase)")
} else {
print(phrase)
}
}
}
}
Options
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import ArgumentParser
@main
struct Repeat: ParsableCommand {
@Flag(help: "Include a counter with each repetition.")
var includeCounter = false
@Option(name: .shortAndLong, help: "The number of times to repeat 'phrase'.")
var count: Int? = nil
@Argument(help: "The phrase to repeat.")
var phrase: String
mutating func run() throws {
let repeatCount = count ?? 2
for i in 1...repeatCount {
if includeCounter {
print("\(i): \(phrase)")
} else {
print(phrase)
}
}
}
}
Implementations
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To write tests
my-awesome-tool
executable
• Difficult to write tests for single executable target
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Package Architecture
• Separate targets executable and frameworks
my-awesome-tool
MyAwesomeKit
MyAwesomeKitTests
executable
framework
test target
Testable
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Package Architecture
• Good for minimize the dependencies
my-awesome-tool
MyAwesomeKit
MyAwesomeKitTests
executable
framework
test target
swift-argument-parser
other dependencies
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Implement your tool!
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For the more usable tools
Tips for getting many users for your tool
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README
• Badges
• https://shields.io/
• Installation methods
• Feature Lists
• LICENSE
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README
• Badges
• https://shields.io/
• Installation methods
• Feature Lists
• LICENSE
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README
• Badges
• https://shields.io/
• Installation methods
• Feature Lists
• LICENSE
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README
• Badges
• https://shields.io/
• Installation methods
• Feature Lists
• LICENSE
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Write articles with DocC
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Build DocC Archive
• Use DocC plugin
• https://github.com/swiftlang/swift-docc-plugin
• Distributing to GitHub Pages
• Update DocC page with every commits
Swift Package DocC Archive GitHub Pages
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Register to Swift Package Index
• Register your package to Swift Package Index
• https://swiftpackageindex.com/add-a-package
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Distribution
• Many methods for distribution
• Source Build
• Binary / Artifact Bundle
• Command Plugin
• Homebrew
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Source Builds
• Nothing to do for developers
• No official way to manage binaries for the user side
• Mint
• https://github.com/yonaskolb/Mint
• No way to distribute prebuilt binaries
• Need to build by users
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Artifact Bundle
• The official distribution format for executables
• Host executables for multi architecture in ZIP file
• https://github.com/swiftlang/swift-evolution/blob/main/proposals/
0305-swiftpm-binary-target-improvements.md
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Build Artifact Bundle
• No official way to make Artifact Bundles
• freddi-kit/ArtifactBundleGen
• Command Plugin to wrap executables in Artifact Bundle format
• https://github.com/freddi-kit/ArtifactBundleGen
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Use Artifact Bundle
• No official way to manage it
• mtj0928/nest
• Download and run prebuilt binary using Artifact Bundle
• https://github.com/mtj0928/nest
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Prepare CI environment
• Must prepare CI environment!
• CI provides some automation
• Tests
• Lint
• Documentation
• Generate DocC Archive
• Distribute to GitHub pages
• Distribution
• Build Artifact Bundle
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GitHub Action
• Using GitHub Action solves everything
• Separate workflows for purposes
• tests/lints/release/docc
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name: Tests
on:
push:
branches:
- main
pull_request:
branches:
- '*'
jobs:
Tests:
strategy:
matrix:
xcode_version:
- "15.2" # 5.9
- "15.4" # 5.10
- "16.0" # 6.0
env:
DEVELOPER_DIR: "/Applications/Xcode_${{ matrix.xcode_version }}.app/Contents/Developer"
runs-on: macos-14
steps:
- name: Get swift version
run: swift --version
- uses: actions/checkout@v2
- name: Run Tests
run: |
swift test --verbose
env:
ENABLE_INTEGRATION_TESTS: 1
IS_CI: 1
Make PR builder
Build for multi versions
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Contribute to community
Make your tools great
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Why publish a tool?
• Improve your presence and career
• Give inspires to communities
• Receive feedback / Make collaboration
Your Team Community
Contributions / Inspires
Feedback / Improvements
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Use your tool
• Just publishing to OSS wouldn’t work fine
• It’s difficult to maintain only for the community
• You should be a heavy user
Great Tool
Contribute to
Community Use your tools
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Conclusion
• Finding issues is the most important topic
• Learn Techniques and Tips to Build Tools
• Contributing to Swift community to publish your tool
• Keep to use your tools
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References
• See my products for examples!
• Scipio
• swift-testing-revolutionary
• Feel free to ask anything on X / Ask the Speaker
• https://x.com/giginet
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Thank you for listening!
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