Swift

Swift tooling standards: SwiftLint, swift-format, swift test, and xcodebuild.

Swift projects use SwiftLint for linting, swift-format for formatting, swift test for SPM-based testing, and xcodebuild for Xcode project testing on macOS CI runners.

Tools

Category	Tool	Purpose
Linter	SwiftLint	Style and convention enforcement
Formatter	swift-format	Apple’s official code formatter
Tests (SPM)	swift test	Swift Package Manager test runner
Tests (Xcode)	xcodebuild	Xcode project test runner (macOS only)

All tools except xcodebuild are pre-installed in the dev-toolchain container. Do not install them on the host.

Configuration

SwiftLint

Config file: .swiftlint.yml at repository root.

# .swiftlint.yml -- DevRail Swift lint configuration
# See: https://realm.github.io/SwiftLint/rule-directory.html

opt_in_rules:
  - closure_body_length
  - collection_alignment
  - contains_over_filter_count
  - discouraged_optional_boolean
  - empty_collection_literal
  - empty_count
  - empty_string
  - force_unwrapping
  - implicitly_unwrapped_optional
  - multiline_arguments
  - overridden_super_call
  - sorted_first_last
  - toggle_bool

excluded:
  - .build
  - Packages
  - DerivedData

line_length:
  warning: 120
  error: 200

type_body_length:
  warning: 300
  error: 500

SwiftLint is invoked with --strict to treat all warnings as errors.

swift-format

Config file: .swift-format (JSON) at repository root.

{
  "version": 1,
  "lineLength": 120,
  "indentation": {
    "spaces": 4
  },
  "maximumBlankLines": 1,
  "respectsExistingLineBreaks": true,
  "lineBreakBeforeControlFlowKeywords": false,
  "lineBreakBeforeEachArgument": true
}

swift-format is Apple’s official Swift formatter. It is authoritative for all code style decisions.

Makefile Targets

Target	Command	Description
`make lint`	`swiftlint lint --strict`	Lint all Swift files
`make format`	`swift-format lint --strict -r .`	Check formatting (diff mode)
`make fix`	`swift-format format -i -r .`	Apply formatting fixes
`make test`	`swift test`	Run SPM test suite (if `Package.swift` exists)

Pre-Commit Hooks

Local Hooks (run on every commit, under 30 seconds)

SwiftLint runs on every commit to catch lint issues:

# .pre-commit-config.yaml -- Swift hooks
repos:
  - repo: https://github.com/realm/SwiftLint
    rev: 0.58.0
    hooks:
      - id: swiftlint
        args: ["lint", "--strict"]

CI-Only (too slow for local hooks)

swift test – SPM test suite
xcodebuild test – Xcode project tests (macOS runners only, outside container)

Notes

SwiftLint is the single linting tool. It is the most widely adopted Swift linter with extensive rule coverage. It runs on both macOS and Linux.
swift-format is the single formatting tool inside the container. Apple’s official formatter handles all code style decisions.
The Swift toolchain is included in the container. The full toolchain (swiftc, swift build, swift test, Swift Package Manager) is COPY’d from the swift:6.1-slim-bookworm builder stage.
Package.swift presence gates SPM testing. If no Package.swift exists, swift test is skipped. Xcode-only projects must configure xcodebuild test in their CI pipeline directly.
xcodebuild does not run inside the container. It requires macOS and Xcode. Configure a separate macOS CI job for Xcode project testing.
Security scanning uses trivy. Trivy scans Package.resolved for known vulnerabilities in Swift package dependencies.
All tools are pre-installed in the dev-toolchain container. Do not install them on the host.
For cross-cutting coding practices and git workflow standards that apply to all languages, see Coding Practices.