SwiftLint

A tool to enforce Swift style and conventions, loosely based on GitHub's Swift Style Guide.

SwiftLint hooks into Clang and SourceKit to use the AST representation of your source files for more accurate results.

Installation

Using Homebrew

brew install swiftlint

You can also install SwiftLint by downloading SwiftLint.pkg from the latest GitHub release and running it.

You can also build from source by cloning this project and running git submodule update --init --recursive; make install (Xcode 7.1).

Usage

Xcode

Integrate SwiftLint into an Xcode scheme to get warnings and errors displayed in the IDE. Just add a new "Run Script Phase" with:

if which swiftlint >/dev/null; then
  swiftlint
else
  echo "SwiftLint does not exist, download from https://github.com/realm/SwiftLint"
fi

Atom

To integrate SwiftLint with Atom install the linter-swiftlint package from APM.

Command Line

$ swiftlint help
Available commands:

   autocorrect  Automatically correct warnings and errors
   help         Display general or command-specific help
   lint         Print lint warnings and errors for the Swift files in the current directory (default command)
   rules        Display the list of rules and their identifiers
   version      Display the current version of SwiftLint

Run swiftlint in the directory containing the Swift files to lint. Directories will be searched recursively.

To specify a list of files when using lint or autocorrect (like the list of files modified by Xcode specified by the ExtraBuildPhase Xcode plugin, or modified files in the working tree based on git ls-files -m) you can do so by passing the option --use-script-input-files and setting the following instance variables: SCRIPT_INPUT_FILE_COUNT and SCRIPT_INPUT_FILE_0, SCRIPT_INPUT_FILE_1... SCRIPT_INPUT_FILE_{SCRIPT_INPUT_FILE_COUNT}.

These are same environment variables set for input files to custom Xcode script phases.

Rules

There are only a small number of rules currently implemented, but we hope the Swift community (that's you!) will contribute more over time. Pull requests are encouraged.

The rules that are currently implemented are mostly there as a starting point and are subject to change.

See the Source/SwiftLintFramework/Rules directory to see the currently implemented rules.

Disable a rule in code

Rules can be disabled with a comment inside a source file with the following format:

// swiftlint:disable <rule>

The rule will be disabled until the end of the file or until the linter sees a matching enable comment:

// swiftlint:enable <rule>

For example:

// swiftlint:disable colon
let noWarning :String = "" // No warning about colons immediately after variable names!
// swiftlint:enable colon
let hasWarning :String = "" // Warning generated about colons immediately after variable names

It's also possible to modify a disable or enable command by appending :previous, :this or :next for only applying the command to the previous, this (current) or next line respectively.

For example:

// swiftlint:disable:next force_cast
let noWarning = NSNumber() as! Int
let hasWarning = NSNumber() as! Int
let noWarning2 = NSNumber() as! Int // swiftlint:disable:this force_cast
let noWarning3 = NSNumber() as! Int
// swiftlint:disable:previous force_cast

Run swiftlint rules to print a list of all available rules and their identifiers.

Configuration

Configure SwiftLint by adding a .swiftlint.yml file from the directory you'll run SwiftLint from. The following parameters can be configured:

disabled_rules: # rule identifiers to exclude from running
  - colon
  - comma
  - control_statement
  - force_cast
  - ...
  # Find all the available rules by running:
  # swiftlint rules
included: # paths to include during linting. `--path` is ignored if present.
  - Source
excluded: # paths to ignore during linting. Takes precedence over `included`.
  - Carthage
  - Pods
  - Source/ExcludedFolder
  - Source/ExcludedFile.swift
# parameterized rules can be customized from this configuration file
line_length: 110
# parameterized rules are first parameterized as a warning level, then error level.
type_body_length:
  - 300 # warning
  - 400 # error
reporter: "csv" # reporter type (xcode, json, csv, checkstyle)

Nested Configurations

SwiftLint supports nesting configuration files for more granular control over the linting process.

• Set the use_nested_configs: true value in your root .swiftlint.yml file
• Include additional .swiftlint.yml files where necessary in your directory structure.
• Each file will be linted using the configuration file that is in its directory or at the deepest level of its parent directories. Otherwise the root configuration will be used.
• excluded, included, and use_nested_configs are ignored for nested configurations.

Auto-correct

SwiftLint can automatically correct certain violations. Files on disk are overwritten with a corrected version.

Please make sure to have backups of these files before running swiftlint autocorrect, otherwise important data may be lost.

Standard linting is disabled while correcting because of the high likelihood of violations (or their offsets) being incorrect after modifying a file while applying corrections.

License

MIT licensed.