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SwiftLint
A tool to enforce Swift style and conventions, loosely based on the now archived GitHub Swift Style Guide. SwiftLint enforces the style guide rules that are generally accepted by the Swift community. These rules are well described in popular style guides likeKodeco's Swift Style Guide.
SwiftLint hooks into Clang andSourceKit to use theAST representation of your source files for more accurate results.
This project adheres to theContributor Covenant Code of Conduct. By participating, you are expected to uphold this code.
Video Introduction
To get a high-level overview of SwiftLint, we encourage you to watch this presentation recorded January 9th, 2017 by JP Simard (transcript provided):
Installation
Swift Package Manager
SwiftLint can be used as a command pluginor a build tool plugin.
Add
.package(url: "https://github.com/SimplyDanny/SwiftLintPlugins", from: "")
to your Package.swift
file to consume the latest release of SwiftLint automatically or pin the dependency to a specific version:
.package(url: "https://github.com/SimplyDanny/SwiftLintPlugins", exact: "")
Therein, replace <version>
with the desired minimum or exact version.
Note
Consuming the plugins directly from the SwiftLint repository comes with several drawbacks. To avoid them and reduce the overhead imposed, it's highly recommended to consume the plugins from the dedicatedSwiftLintPlugins repository, even though plugins from the SwiftLint repository are also absolutely functional. If the plugins from SwiftLint are preferred, just use the URLhttps://github.com/realm/SwiftLint
in the package declarations above.
However, SwiftLintPluginsfacilitates plugin adoption massively. It lists some of the reasons that drive the plugins as provided by SwiftLint itself very troublesome. Since the plugin code and the releases are kept in sync, there is no difference in functionality between the two, but you spare yourself a lot of time and trouble using the dedicated plugins repository.
This document assumes you're relying on SwiftLintPlugins.
Xcode Package Dependency
Use the following link to add SwiftLint as a Package Dependency to an Xcode project:
https://github.com/SimplyDanny/SwiftLintPlugins
Homebrew
CocoaPods
Add the following to your Podfile
:
This will download the SwiftLint binaries and dependencies in Pods/
during your next pod install
execution and will allow you to invoke it via${PODS_ROOT}/SwiftLint/swiftlint
in your Script Build Phases.
Installing via Cocoapods also enables pinning to a specific version of SwiftLint rather than simply the latest (which is the case withHomebrew).
Note that this will add the SwiftLint binaries, its dependencies' binaries, and the Swift binary library distribution to the Pods/
directory, so checking in this directory to SCM such as Git is discouraged.
Mint
mint install realm/SwiftLint
Bazel
Put this in your MODULE.bazel
:
bazel_dep(name = "swiftlint", version = "0.52.4", repo_name = "SwiftLint")
Or put this in your WORKSPACE
:
WORKSPACE
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive( name = "build_bazel_rules_apple", sha256 = "390841dd5f8a85fc25776684f4793d56e21b098dfd7243cd145b9831e6ef8be6", url = "https://github.com/bazelbuild/rules_apple/releases/download/2.4.1/rules_apple.2.4.1.tar.gz", )
load( "@build_bazel_rules_apple//apple:repositories.bzl", "apple_rules_dependencies", )
apple_rules_dependencies()
load( "@build_bazel_rules_swift//swift:repositories.bzl", "swift_rules_dependencies", )
swift_rules_dependencies()
load( "@build_bazel_rules_swift//swift:extras.bzl", "swift_rules_extra_dependencies", )
swift_rules_extra_dependencies()
http_archive( name = "SwiftLint", sha256 = "c6ea58b9c72082cdc1ada4a2d48273ecc355896ed72204cedcc586b6ccb8aca6", url = "https://github.com/realm/SwiftLint/releases/download/0.52.4/bazel.tar.gz", )
load("@SwiftLint//bazel:repos.bzl", "swiftlint_repos")
swiftlint_repos()
load("@SwiftLint//bazel:deps.bzl", "swiftlint_deps")
swiftlint_deps()
Then you can run SwiftLint in the current directory with this command:
bazel run -c opt @SwiftLint//:swiftlint
Pre-Built Package
Download SwiftLint.pkg
from thelatest GitHub release and run it.
From Source
Make sure the build tool Bazel and a recent Swift toolchain are installed and all tools are discoverable in your PATH
.
To build SwiftLint, clone this repository and run make install
.
Setup
Important
While it may seem intuitive to run SwiftLint before compiling Swift source files to exit a build early when there are lint violations, it is important to understand that SwiftLint is designed to analyze valid source code that is compilable. Non-compiling code can very easily lead to unexpected and confusing results, especially when executing with --fix
/--autocorrect
command line arguments.
Build Tool Plugins
SwiftLint can be used as a build tool plugin for bothSwift Package projectsand Xcode projects.
The build tool plugin determines the SwiftLint working directory by locating the topmost config file within the package/project directory. If a config file is not found therein, the package/project directory is used as the working directory.
The plugin throws an error when it is unable to resolve the SwiftLint working directory. For example, this will occur in Xcode projects where the target's Swift files are not located within the project directory.
To maximize compatibility with the plugin, avoid project structures that require the use of the --config
option.
Swift Package Projects
Note
Requires installing via Swift Package Manager.
Build tool plugins run when building each target. When a project has multiple targets, the plugin must be added to the desired targets individually.
To do this, add the plugin to the target(s) to be linted as follows:
.target( ... plugins: [.plugin(name: "SwiftLintBuildToolPlugin", package: "SwiftLintPlugins")] ),
Swift Package Command Plugin
Note
Requires installing via Swift Package Manager.
The command plugin enables running SwiftLint from the command line as follows:
swift package plugin swiftlint
Xcode Projects
Note
Requires installing via Xcode Package Dependency.
Build tool plugins run as a build phase of each target. When a project has multiple targets, the plugin must be added to the desired targets individually.
To do this, add the SwiftLintBuildToolPlugin
to the Run Build Tool Plug-ins
phase of the Build Phases
for the target(s) to be linted.
Tip
When using the plugin for the first time, be sure to trust and enable it when prompted. If a macros build warning exists, select it to trust and enable the macros as well.
For unattended use (e.g. on CI), package plugin and macro validations can be disabled with either of the following:
- Using
xcodebuild
options:
-skipPackagePluginValidation
-skipMacroValidation - Setting Xcode defaults:
defaults write com.apple.dt.Xcode IDESkipPackagePluginFingerprintValidatation -bool YES
defaults write com.apple.dt.Xcode IDESkipMacroFingerprintValidation -bool YES
Important
The unattended use options bypass Xcode's validation dialogs and implicitly trust all plugins and macros, which has security implications.
Unexpected Xcode Project Structures
Project structures where SwiftLint's configuration file is located outside of the package/project directory are not directly supported by the build tool plugin. This is because it isn't possible to pass arguments to build tool plugins (e.g., passing the config file path).
If your project structure doesn't work directly with the build tool plugin, please consider one of the following options:
- To use a config file located outside the package/project directory, a config file may be added to that directory specifying a parent config path to the other config file, e.g.,
parent_config: path/to/.swiftlint.yml
. - You can also consider the use of aRun Script Build Phase in place of the build tool plugin.
Xcode Run Script Build Phase
Note
Based upon the installation method used, the shell command syntax in the Run Script Build Phase may be different or additional configuration could be required. Refer to the installation instructions for more information.
If the build tool plugin does not work for your project setup or when additional custom setup is required, SwiftLint can be added as a Run Script Build Phase. This is useful when a project setup relies on the --config
SwiftLint option; or to lint all targets together in a single swiftlint
invocation. File inclusions and exclusions can be configured in the.swiftlint.yml configuration.
To do this, add a custom script to a Run Script
phase of the Build Phases
of the primary app target, after the Compile Sources
phase. Use the following script implementation:
if command -v swiftlint >/dev/null 2>&1
then
swiftlint
else
echo "warning: swiftlint
command not found - See https://github.com/realm/SwiftLint#installation for installation instructions."
fi
If you're using the SwiftLintPlugin in a Swift package, you may refer to the swiftlint
executable in the following way:
SWIFT_PACKAGE_DIR="${BUILD_DIR%Build/}SourcePackages/artifacts" SWIFTLINT_CMD=$(ls "$SWIFT_PACKAGE_DIR"/swiftlintplugins/SwiftLintBinary/SwiftLintBinary.artifactbundle/swiftlint--macos/bin/swiftlint | head -n 1)
if test -f "$SWIFTLINT_CMD" 2>&1
then
"$SWIFTLINT_CMD"
else
echo "warning: swiftlint
command not found - See https://github.com/realm/SwiftLint#installation for installation instructions."
fi
Note
The SWIFTLINT_CMD
path uses the default Xcode configuration and has been tested on Xcode 15/16. In case of another configuration (e.g. a custom Swift package path), please adapt the values accordingly.
Tip
Uncheck Based on dependency analysis
to run swiftlint
on all incremental builds, suppressing the unspecified outputs warning.
Consideration for Xcode 15.0
Xcode 15 made a significant change by setting the default value of theENABLE_USER_SCRIPT_SANDBOXING
build setting from NO
to YES
. As a result, SwiftLint encounters an error related to missing file permissions, which typically manifests aserror: Sandbox: swiftlint(19427) deny(1) file-read-data.
To resolve this issue, it is necessary to manually set theENABLE_USER_SCRIPT_SANDBOXING
setting to NO
for the specific target that SwiftLint is being configured for.
Consideration for Apple Silicon
If you installed SwiftLint via Homebrew on Apple Silicon, you might experience this warning:
warning: SwiftLint not installed, download from https://github.com/realm/SwiftLint
That is because Homebrew on Apple Silicon installs the binaries into the/opt/homebrew/bin
folder by default. To instruct Xcode where to find SwiftLint, you can either add /opt/homebrew/bin
to the PATH
environment variable in your build phase:
if [[ "$(uname -m)" == arm64 ]] then export PATH="/opt/homebrew/bin:$PATH" fi
if command -v swiftlint >/dev/null 2>&1
then
swiftlint
else
echo "warning: swiftlint
command not found - See https://github.com/realm/SwiftLint#installation for installation instructions."
fi
or you can create a symbolic link in /usr/local/bin
pointing to the actual binary:
ln -s /opt/homebrew/bin/swiftlint /usr/local/bin/swiftlint
Additional Considerations
If you wish to fix violations as well, your script could runswiftlint --fix && swiftlint
instead of just swiftlint
. This will mean that all correctable violations are fixed while ensuring warnings show up in your project for remaining violations.
If you've installed SwiftLint via CocoaPods the script should look like this:
"${PODS_ROOT}/SwiftLint/swiftlint"
Visual Studio Code
To integrate SwiftLint with Visual Studio Code, install thevscode-swiftlintextension from the marketplace.
Fastlane
You can use the officialswiftlint fastlane actionto run SwiftLint as part of your fastlane process.
swiftlint( mode: :lint, # SwiftLint mode: :lint (default) or :autocorrect executable: "Pods/SwiftLint/swiftlint", # The SwiftLint binary path (optional). Important if you've installed it via CocoaPods path: "/path/to/lint", # Specify path to lint (optional) output_file: "swiftlint.result.json", # The path of the output file (optional) reporter: "json", # The custom reporter to use (optional) config_file: ".swiftlint-ci.yml", # The path of the configuration file (optional) files: [ # List of files to process (optional) "AppDelegate.swift", "path/to/project/Model.swift" ], ignore_exit_status: true, # Allow fastlane to continue even if SwiftLint returns a non-zero exit status (Default: false) quiet: true, # Don't print status logs like 'Linting ' & 'Done linting' (Default: false) strict: true # Fail on warnings? (Default: false) )
Docker
SwiftLint is also available as a Docker image usingUbuntu
. So just the first time you need to pull the docker image using the next command:
docker pull ghcr.io/realm/swiftlint:latest
Then following times, you just run swiftlint
inside of the docker like:
docker run -it -v pwd
:pwd
-w pwd
ghcr.io/realm/swiftlint:latest
This will execute swiftlint
in the folder where you are right now (pwd
), showing an output like:
$ docker run -it -v pwd
:pwd
-w pwd
ghcr.io/realm/swiftlint:latest
Linting Swift files in current working directory
Linting 'RuleDocumentation.swift' (1/490)
...
Linting 'YamlSwiftLintTests.swift' (490/490)
Done linting! Found 0 violations, 0 serious in 490 files.
Here you have more documentation about the usage ofDocker Images.
Command Line Usage
$ swiftlint help OVERVIEW: A tool to enforce Swift style and conventions.
USAGE: swiftlint
OPTIONS: --version Show the version. -h, --help Show help information.
SUBCOMMANDS: analyze Run analysis rules docs Open SwiftLint documentation website in the default web browser generate-docs Generates markdown documentation for selected group of rules lint (default) Print lint warnings and errors baseline Operations on existing baselines reporters Display the list of reporters and their identifiers rules Display the list of rules and their identifiers version Display the current version of SwiftLint
See 'swiftlint help ' for detailed help.
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 analyze
(like the list of files modified by Xcode specified by theExtraBuildPhase 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 - 1}
. Similarly, files can be read from file lists by passing the option --use-script-input-file-lists
and setting the following instance variables: SCRIPT_INPUT_FILE_LIST_COUNT
and SCRIPT_INPUT_FILE_LIST_0
, SCRIPT_INPUT_FILE_LIST_1
, ...,SCRIPT_INPUT_FILE_LIST_{SCRIPT_INPUT_FILE_LIST_COUNT - 1}
.
These are same environment variables set for input files tocustom Xcode script phases.
Working With Multiple Swift Versions
SwiftLint hooks into SourceKit so it continues working even as Swift evolves!
This also keeps SwiftLint lean, as it doesn't need to ship with a full Swift compiler, it just communicates with the official one you already have installed on your machine.
You should always run SwiftLint with the same toolchain you use to compile your code.
You may want to override SwiftLint's default Swift toolchain if you have multiple toolchains or Xcodes installed.
Here's the order in which SwiftLint determines which Swift toolchain to use:
$XCODE_DEFAULT_TOOLCHAIN_OVERRIDE
$TOOLCHAIN_DIR
or$TOOLCHAINS
xcrun -find swift
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain
/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain
~/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain
~/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain
sourcekitd.framework
is expected to be found in the usr/lib/
subdirectory of the value passed in the paths above.
You may also set the TOOLCHAINS
environment variable to the reverse-DNS notation that identifies a Swift toolchain version:
TOOLCHAINS=com.apple.dt.toolchain.Swift_2_3 swiftlint --fix
On Linux, SourceKit is expected to be located in/usr/lib/libsourcekitdInProc.so
or specified by the LINUX_SOURCEKIT_LIB_PATH
environment variable.
Git pre-commit
Hook
SwiftLint can be run as a pre-commit hook. Once installed, add this to the.pre-commit-config.yaml
in the root of your repository:
repos:
- repo: https://github.com/realm/SwiftLint
rev: 0.57.1
hooks:
- id: swiftlint
Adjust rev
to the SwiftLint version of your choice. pre-commit autoupdate
can be used to update to the current version.
SwiftLint can be configured using entry
to apply fixes and fail on errors:
- repo: https://github.com/realm/SwiftLint
rev: 0.57.1
hooks:
- id: swiftlint entry: swiftlint --fix --strict
Rules
Over 200 rules are included in SwiftLint and the Swift community (that's you!) continues to contribute more over time.Pull requestsare encouraged.
You can find an updated list of rules and more information about themhere.
You can also check theSource/SwiftLintBuiltInRules/Rulesdirectory to see their implementation.
Opt-In Rules
opt_in_rules
are disabled by default (i.e., you have to explicitly enable them in your configuration file).
Guidelines on when to mark a rule as opt-in:
- A rule that can have many false positives (e.g.
empty_count
) - A rule that is too slow
- A rule that is not general consensus or is only useful in some cases (e.g.
force_unwrapping
)
Disable rules in code
Rules can be disabled with a comment inside a source file with the following format:
// swiftlint:disable <rule1> [<rule2> <rule3>...]
The rules will be disabled until the end of the file or until the linter sees a matching enable comment:
// swiftlint:enable <rule1> [<rule2> <rule3>...]
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
Including the all
keyword will disable all rules until the linter sees a matching enable comment:
// swiftlint:disable all
// swiftlint:enable all
For example:
// swiftlint:disable all let noWarning :String = "" // No warning about colons immediately after variable names! let i = "" // Also no warning about short identifier names // swiftlint:enable all let hasWarning :String = "" // Warning generated about colons immediately after variable names let y = "" // Warning generated about short identifier 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:
Rule inclusion:
disabled_rules
: Disable rules from the default enabled set.opt_in_rules
: Enable rules that are not part of the default set. The specialall
identifier will enable all opt in linter rules, except the ones listed indisabled_rules
.only_rules
: Only the rules specified in this list will be enabled. Cannot be specified alongsidedisabled_rules
oropt_in_rules
.analyzer_rules
: This is an entirely separate list of rules that are only run by theanalyze
command. All analyzer rules are opt-in, so this is the only configurable rule list, there are no equivalents fordisabled_rules
andonly_rules
. The specialall
identifier can also be used here to enable all analyzer rules, except the ones listed indisabled_rules
.
By default, SwiftLint uses a set of sensible default rules you can adjust:
disabled_rules: # rule identifiers turned on by default to exclude from running
- colon
- comma
- control_statement opt_in_rules: # some rules are turned off by default, so you need to opt-in
- empty_count # find all the available rules by running:
swiftlint rules
Alternatively, specify all rules explicitly by uncommenting this option:
only_rules: # delete disabled_rules
& opt_in_rules
if using this
- empty_parameters
- vertical_whitespace
analyzer_rules: # rules run by swiftlint analyze
- explicit_self
Case-sensitive paths to include during linting. Directory paths supplied on the
command line will be ignored.
included:
- Sources
excluded: # case-sensitive paths to ignore during linting. Takes precedence over
included
- Carthage
- Pods
- Sources/ExcludedFolder
- Sources/ExcludedFile.swift
- Sources/*/ExcludedFile.swift # exclude files with a wildcard
If true, SwiftLint will not fail if no lintable files are found.
allow_zero_lintable_files: false
If true, SwiftLint will treat all warnings as errors.
strict: false
If true, SwiftLint will treat all errors as warnings.
lenient: false
The path to a baseline file, which will be used to filter out detected violations.
baseline: Baseline.json
The path to save detected violations to as a new baseline.
write_baseline: Baseline.json
If true, SwiftLint will check for updates after linting or analyzing.
check_for_updates: true
configurable rules can be customized from this configuration file
binary rules can set their severity level
force_cast: warning # implicitly force_try: severity: warning # explicitly
rules that have both warning and error levels, can set just the warning level
implicitly
line_length: 110
they can set both implicitly with an array
type_body_length:
- 300 # warning
- 400 # error
or they can set both explicitly
file_length: warning: 500 error: 1200
naming rules can set warnings/errors for min_length and max_length
additionally they can set excluded names
type_name: min_length: 4 # only warning max_length: # warning and error warning: 40 error: 50 excluded: iPhone # excluded via string allowed_symbols: ["_"] # these are allowed in type names identifier_name: min_length: # only min_length error: 4 # only error excluded: # excluded via string array - id - URL - GlobalAPIKey reporter: "xcode" # reporter type (xcode, json, csv, checkstyle, codeclimate, junit, html, emoji, sonarqube, markdown, github-actions-logging, summary)
You can also use environment variables in your configuration file, by using ${SOME_VARIABLE}
in a string.
Defining Custom Rules
In addition to the rules that the main SwiftLint project ships with, SwiftLint can also run two types of custom rules that you can define yourself in your own projects:
1. Swift Custom Rules
These rules are written the same way as the Swift-based rules that ship with SwiftLint so they're fast, accurate, can leverage SwiftSyntax, can be unit tested, and more.
Using these requires building SwiftLint with Bazel as described inthis video or its associated code ingithub.com/jpsim/swiftlint-bazel-example.
2. Regex Custom Rules
You can define custom regex-based rules in your configuration file using the following syntax:
custom_rules: pirates_beat_ninjas: # rule identifier included: - ".*\.swift" # regex that defines paths to include during linting. optional. excluded: - ".*Test\.swift" # regex that defines paths to exclude during linting. optional name: "Pirates Beat Ninjas" # rule name. optional. regex: "([nN]inja)" # matching pattern capture_group: 0 # number of regex capture group to highlight the rule violation at. optional. match_kinds: # SyntaxKinds to match. optional. - comment - identifier message: "Pirates are better than ninjas." # violation message. optional. severity: error # violation severity. optional. no_hiding_in_strings: regex: "([nN]inja)" match_kinds: string
This is what the output would look like:
It is important to note that the regular expression pattern is used with the flags s
and m
enabled, that is .
matches newlinesand ^
/$
match the start and end of lines, respectively. If you do not want to have .
match newlines, for example, the regex can be prepended by (?-s)
.
You can filter the matches by providing one or more match_kinds
, which will reject matches that include syntax kinds that are not present in this list. Here are all the possible syntax kinds:
argument
attribute.builtin
attribute.id
buildconfig.id
buildconfig.keyword
comment
comment.mark
comment.url
doccomment
doccomment.field
identifier
keyword
number
objectliteral
parameter
placeholder
string
string_interpolation_anchor
typeidentifier
All syntax kinds used in a snippet of Swift code can be extracted askingSourceKitten. For example,sourcekitten syntax --text "struct S {}"
delivers
source.lang.swift.syntaxtype.keyword
for thestruct
keyword andsource.lang.swift.syntaxtype.identifier
for its nameS
which match to keyword
and identifier
in the above list.
If using custom rules in combination with only_rules
, you must include the literal string custom_rules
in the only_rules
list:
only_rules:
- custom_rules
custom_rules: no_hiding_in_strings: regex: "([nN]inja)" match_kinds: string
Unlike Swift custom rules, you can use official SwiftLint builds (e.g. from Homebrew) to run regex custom rules.
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 runningswiftlint --fix
, 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.
Analyze
The swiftlint analyze
command can lint Swift files using the full type-checked AST. The compiler log path containing the clean swiftc
build command invocation (incremental builds will fail) must be passed to analyze
via the --compiler-log-path
flag. e.g. --compiler-log-path /path/to/xcodebuild.log
This can be obtained by
- Cleaning DerivedData (incremental builds won't work with analyze)
- Running
xcodebuild -workspace {WORKSPACE}.xcworkspace -scheme {SCHEME} > xcodebuild.log
- Running
swiftlint analyze --compiler-log-path xcodebuild.log
Analyzer rules tend to be considerably slower than lint rules.
Using Multiple Configuration Files
SwiftLint offers a variety of ways to include multiple configuration files. Multiple configuration files get merged into one single configuration that is then applied just as a single configuration file would get applied.
There are quite a lot of use cases where using multiple configuration files could be helpful:
For instance, one could use a team-wide shared SwiftLint configuration while allowing overrides in each project via a child configuration file.
Team-Wide Configuration:
disabled_rules:
- force_cast
Project-Specific Configuration:
opt_in_rules:
- force_cast
Child/Parent Configs (Locally)
You can specify a child_config
and/or a parent_config
reference within a configuration file. These references should be local paths relative to the folder of the configuration file they are specified in. This even works recursively, as long as there are no cycles and no ambiguities.
A child config is treated as a refinement and thus has a higher priority, while a parent config is considered a base with lower priority in case of conflicts.
Here's an example, assuming you have the following file structure:
ProjectRoot |_ .swiftlint.yml |_ .swiftlint_refinement.yml |_ Base |_ .swiftlint_base.yml
To include both the refinement and the base file, your .swiftlint.yml
should look like this:
child_config: .swiftlint_refinement.yml parent_config: Base/.swiftlint_base.yml
When merging parent and child configs, included
and excluded
configurations are processed carefully to account for differences in the directory location of the containing configuration files.
Child/Parent Configs (Remote)
Just as you can provide local child_config
/parent_config
references, instead of referencing local paths, you can just put urls that lead to configuration files. In order for SwiftLint to detect these remote references, they must start with http://
or https://
.
The referenced remote configuration files may even recursively reference other remote configuration files, but aren't allowed to include local references.
Using a remote reference, your .swiftlint.yml
could look like this:
parent_config: https://myteamserver.com/our-base-swiftlint-config.yml
Every time you run SwiftLint and have an Internet connection, SwiftLint tries to get a new version of every remote configuration that is referenced. If this request times out, a cached version is used if available. If there is no cached version available, SwiftLint fails – but no worries, a cached version should be there once SwiftLint has run successfully at least once.
If needed, the timeouts for the remote configuration fetching can be specified manually via the configuration file(s) using theremote_timeout
/remote_timeout_if_cached
specifiers. These values default to 2 seconds or 1 second, respectively.
Command Line
Instead of just providing one configuration file when running SwiftLint via the command line, you can also pass a hierarchy, where the first configuration is treated as a parent, while the last one is treated as the highest-priority child.
A simple example including just two configuration files looks like this:
swiftlint --config .swiftlint.yml --config .swiftlint_child.yml
Nested Configurations
In addition to a main configuration (the .swiftlint.yml
file in the root folder), you can put other configuration files named .swiftlint.yml
into the directory structure that then get merged as a child config, but only with an effect for those files that are within the same directory as the config or in a deeper directory where there isn't another configuration file. In other words: Nested configurations don't work recursively – there's a maximum number of one nested configuration per file that may be applied in addition to the main configuration.
.swiftlint.yml
files are only considered as a nested configuration if they have not been used to build the main configuration already (e. g. by having been referenced via something like child_config: Folder/.swiftlint.yml
). Also, parent_config
/child_config
specifications of nested configurations are getting ignored because there's no sense to that.
If one (or more) SwiftLint file(s) are explicitly specified via the --config
parameter, that configuration will be treated as an override, no matter whether there exist other .swiftlint.yml
files somewhere within the directory.So if you want to use nested configurations, you can't use the --config
parameter.
License
About
SwiftLint is utterly maintained by volunteers contributing to its success entirely in their free time. As such, SwiftLint isn't a commercial product in any way.
Be kind to the people maintaining SwiftLint as a hobby and accept that their time is limited. Support them by contributing to the project, reporting issues, and helping others in the community.
Special thanks go to MacStadium for providing physical Mac mini machines to run our performance tests.
We also thank Realm (now MongoDB) for their inital contributions and setup of the project.