Over 75 rules are included in SwiftLint and the Swift community (that's you!)
continues to contribute more over time.
Pull requests are encouraged.
See the Source/SwiftLintFramework/Rules
directory to see the currently implemented rules.
opt_in_rules are disabled by default (i.e., you have to explicitly enable them
in your configuration file).
Guidelines on when to implement 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
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 not from the default set.whitelist_rules: Acts as a whitelist, only the rules specified in this list
will be enabled. Can not be specified alongside disabled_rules or
opt_in_rules.
disabled_rules: # rule identifiers to exclude from running
- colon
- comma
- control_statement
opt_in_rules: # some rules are only opt-in
- empty_count
# 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
# 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
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, junit, html, emoji)
Defining Custom Rules
You can define custom regex-based rules in you 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: "([n,N]inja)" # matching pattern
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: "([n,N]inja)"
match_kinds: string
This is what the output would look like:
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
Nested Configurations
SwiftLint supports nesting configuration files for more granular control over
the linting process.
- 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 and included 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.
