When starting a new app, I usually like to set up an automatic code formatter. By agreeing with your team about the rules, and setting a tool to automatically enforce them, you can avoid formatting discussions in the PRs, and you can achieve a codebase where every file looks similar in format.

I like to use SwiftFormat as the formatter for my projects.

1. Install using SPM

Following the instructions on their Readme:

1. Create a folder called BuildTools in the same folder as your xcodeproj file.

mkdir BuildTools

2. Create a file called Empty.swift with nothing in it inside the BuildTools folder.

cd BuildTools && touch Empty.swift

3. Create a file called Package.swift in the BuildTools folder, with the following contents:

// swift-tools-version:5.7
import PackageDescription

let package = Package(
    name: "BuildTools",
    platforms: [.macOS(.v13)],
    dependencies: [
        .package(url: "https://github.com/nicklockwood/SwiftFormat", from: "0.51.13")
    ],
    targets: [.target(name: "BuildTools", path: "")]
)

touch Package.swift && vim Package.swift -> Then paste the contents from above and save.

2. Add a BuildPhase to the project

1. Click on your project in the file list, choose your target under TARGETS, click the Build Phases tab.

2. Add a New Run Script Phase by clicking the little plus icon in the top left.

3. Uncheck the Based on dependency analysis checkbox.

4. Drag the new Run Script phase above the Compile Sources phase, expand it and paste the following script:

SDKROOT=(xcrun --sdk macosx --show-sdk-path)
swift run \
    -c release \
    --package-path BuildTools \
    swiftformat "$SRCROOT" \
    --minversion 0.51.13 \
    --config BuildTools/.swiftformat \
    --swiftversion 5.7

5. It is recommended to add the following to your .gitignore file: BuildTools/.build and BuildTools/.swiftpm.

vim .gitignore

Paste the following:

BuildTools/.build
BuildTools/.swiftpm

Note: Running SwiftFormat has the undesired side-effect of removing the undo/redo actions, so I recommend adding the BuildPhase to one of the test’s target instead of the app’s target.

3. Configure the Rules

SwiftFormat comes with a set of rules to choose from. Here is the list I like to use:

# format options
--allman false
--indent 4
--maxwidth 120
--commas inline
--decimalgrouping 3
--wraparguments before-first

# rules
--enable isEmpty
--disable redundantType
--disable wrapMultilineStatementBraces

To configure the rules:

cd BuildTools && touch .swiftformat && vim .swiftformat -> Paste the rules from above and save the file.

4. Test the implementation

1. Build the target where you added the Build Phase.

Note: The first time you build it, the phase will fetch the SwiftFormat package from the internet, so it might take a while, after that one, every build should be fast.

2. Check that the files where modified after the build.

Before:

struct ContentView: View {
    @State private var isPresentingSheet: Bool = false
    var body: some View {
        VStack {
            Image(systemName: "globe")
                .imageScale(.large)
            .foregroundColor(.accentColor)
            Text("Hello, world!"
                        )
            Button {
                isPresentingSheet = true }
        label: {
                Label("Present Bottom Sheet", image: "star")
            }
        }
        .padding()
        .sheet(
            isPresented: $isPresentingSheet)
        {
            Text("Hey!")
        }
    }
}

After:

struct ContentView: View {
    @State private var isPresentingSheet: Bool = false
    var body: some View {
        VStack {
            Image(systemName: "globe")
                .imageScale(.large)
                .foregroundColor(.accentColor)
            Text(
                "Hello, world!"
            )
            Button {
                isPresentingSheet = true
            }
            label: {
                Label("Present Bottom Sheet", image: "star")
            }
        }
        .padding()
        .sheet(
            isPresented: $isPresentingSheet
        ) {
            Text("Hey!")
        }
    }
}

Here is an example repository where everything is configured.

Run SwiftFormat from the console

Sometimes you want to run the formatter from the console directly, to do so, I like to set up some bash scripts and add them to my .zshrc for convenience:

1. Create the script

cd ~/path-to-the-project-root && swift run -c release --package-path BuildTools swiftformat . --minversion 0.51.13 --config BuildTools/.swiftformat --swiftversion 5.7

2. Add it to the .zshrc

vim ~/.zshrc

Add a new entry:

alias format='Paste the script from point 1 here'

Save it.

3. Reload the zshrc file:

source ~/.zshrc

4. Run the formatter from anywhere in the console:

format

I hope you found this article helpful, see you next time! 😄