Swift Language Guide¶

linthis uses swiftlint for linting and swift-format for formatting Swift code.

Supported File Extensions¶

.swift

Required Tools¶

Linter: swiftlint¶

# macOS (recommended)
brew install swiftlint

# Or via Mint
mint install realm/SwiftLint

# Verify installation
swiftlint version

Formatter: swift-format¶

# macOS
brew install swift-format

# Or build from source
git clone https://github.com/apple/swift-format.git
cd swift-format
swift build -c release

# Verify installation
swift-format --version

Configuration¶

Basic Example¶

# .linthis/config.toml

[swift]
max_complexity = 15
excludes = ["Pods/**", "Carthage/**", ".build/**"]

Disable Specific Rules¶

[swift.rules]
disable = [
    "line_length",
    "trailing_whitespace"
]

Custom Rules¶

[[rules.custom]]
code = "swift/no-print"
pattern = "\\bprint\\s*\\("
message = "Use os_log or Logger instead of print()"
severity = "warning"
languages = ["swift"]

[[rules.custom]]
code = "swift/force-unwrap"
pattern = "\\!(?![=])"
message = "Avoid force unwrapping"
severity = "warning"
suggestion = "Use optional binding or nil coalescing"
languages = ["swift"]

CLI Usage¶

# Check Swift files only
linthis -c --lang swift

# Format Swift files only
linthis -f --lang swift

SwiftLint Configuration¶

Create .swiftlint.yml:

disabled_rules:
  - trailing_whitespace
  - line_length

opt_in_rules:
  - empty_count
  - closure_spacing

line_length:
  warning: 120
  error: 150

excluded:
  - Pods
  - Carthage
  - .build

Swift-Format Configuration¶

Create .swift-format:

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

Common Issues¶

SwiftLint not found¶

Warning: No swift linter available for swift files
  Install: brew install swiftlint

Note: SwiftLint is primarily macOS-only.

SPM packages being checked¶

Add to excludes:

[swift]
excludes = [".build/**", "Package.resolved"]

Xcode-managed files¶

Add generated files to excludes:

[swift]
excludes = ["*.generated.swift", "R.generated.swift"]

Best Practices¶

Use .swiftlint.yml: Configure rules per project
Force unwrap detection: Warn on ! usage
SPM exclusions: Exclude .build directory
Line length: 120 characters is common for Swift projects