SwiftLint

We are introducing mandatory linting for iOS. A linter is a tool to enforce Swift style and conventions.

Linting is important and we want to adapt a uniform linter across all iOS projects.

Example of SwiftLint

SwiftLint Installation

To use swiftlint, we just have to install it with brew. In terminal, run:

brew install swiftlint

Configure With 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 "warning: SwiftLint not installed, download from https://github.com/realm/SwiftLint"
fi

Adding a swiftlint.yml

This file will control the rules and how the the swiftlint framework will operate. In the root directory of the project, create a new file called .swiftlint.yml

A swiftlint.yml defines all the rules we want to use/ignore when linting. Here is a good starting file, but feel free to modify it as needed. Make sure you replace YOUR_PROJECT_FOLDER with your project folder name.

disabled_rules: # rule identifiers to exclude from running
- variable_name
- nesting
- function_parameter_count
opt_in_rules: # some rules are only opt-in
- control_statement
- empty_count
- colon
- comma
included: # paths to include during linting. `--path` is ignored if present.
- YOUR_PROJECT_NAME
excluded: # paths to ignore during linting. Takes precedence over `included`.
- Pods
- YOUR_PROJECT_NAME/AppDelegate.swift

# configurable rules can be customized from this configuration file
# binary rules can set their severity level
force_cast: warning # implicitly. Give warning only for force casting

force_try:
severity: warning # explicitly. Give warning only for force try

type_body_length:
- 300 # warning
- 400 # error

# or they can set both explicitly
file_length:
warning: 500
error: 800

large_tuple: # warn user when using 3 values in tuple, give error if there are 4
- 3
- 4
# 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: 30
error: 35
reporter: "xcode"

You can read more about swiftlint rules here.

SwiftLint Autocorrect

One of the cool features swiftlint is autocorrect. SwiftLint can automagically fix simple issues with your code. To run this, just go into the root directory on termial and run swiftlint autocorrect