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Style is important when writing code. Following conventions and guidelines helps tell the story of our code to our team and our future-selves. Today we'll learn about SwiftLint, a tool from Realm that can help us enforce Swift conventions and best practices. Let's get started.

SwiftLint provides a downloadable install package on its Github page, but here we'll install using Homebrew. We'll run:

brew install swiftlint

Now, we can run swiftlint rules at the command line to see all the different convetions and standards that will be enforced. We can also run swiftlint lint in the root directory of our project to see what rules we're breaking right in the terminal.

Our next step is to add SwiftLint as a build phase to our project.

We'll head over to our project's settings, then to the Build Phases tab. We'll click the + button to add a** new “Run Script” phase**. We'll name it “SwiftLint” and give it the follow script content:

if which swiftlint > /dev/null; then
  echo “Download SwiftLint: https://github.com/realm/SwiftLint"

Now when we build our project, SwiftLint will let us know via regular Errors and Warnings in Xcode when there's something to fix.

We can configure how SwiftLint behaves in complete detail by creating a new file called .swiftlint.yml and putting it in the root directory of our project. We can fill out this file to customize (for example) which conventions are enforced:

  - colon
  - control_statement

We can disable rules “in-line” in our code with special comments:

// swiftlint:disable colon
let noWarning :String = "" // No warning about colon placement
// swiftlint:enable colon
let yesWarning :String = "" // Warning generated

Finally, SwiftLint can correct some violations (trailing_newline, trailing_semicolon, etc.). Just run swiftlint autocorrect.

More info about SwiftLint can be found at git.io/swiftlint