R.swift

Get strong typed, autocompleted resources like images, fonts and segues in Swift projects

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⚠️ R.swift and Xcode 10 / Swift 4.2

The currently latest release of R.swift (5.0.0.alpha.2) supports Swift 4.2, but with a couple of known issues:

When using the new build system and using R.swift as a build step:

• The initial compile will fail if no output file is configured
• However, when setting an output file, subsequent incremental build won't run the R.swift build step

Current known work-arounds for these issues:

1. Use the Legacy Build System
2. Don't configure an output file, but compile twice (difficult on a CI)
3. Configure an output file, but always do a clean build when an asset has been added (difficult to remember when developing)
4. Commit the R.generated.swift file to source control, so the CI has the lastest version from development

We're working on finding a better solution to these issues, see also: mac-cain13#456

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Why use this?

It makes your code that uses resources:

• Fully typed, less casting and guessing what a method will return
• Compile time checked, no more incorrect strings that make your app crash at runtime
• Autocompleted, never have to guess that image name again

Currently you type:

let icon = UIImage(named: "settings-icon")
let font = UIFont(name: "San Francisco", size: 42)
let color = UIColor(named: "indictator highlight")
let viewController = CustomViewController(nibName: "CustomView", bundle: nil)
let string = String(format: NSLocalizedString("welcome.withName", comment: ""), locale: NSLocale.current, "Arthur Dent")

With R.swift it becomes:

let icon = R.image.settingsIcon()
let font = R.font.sanFrancisco(size: 42)
let color = R.color.indicatorHighlight()
let viewController = CustomViewController(nib: R.nib.customView)
let string = R.string.localizable.welcomeWithName("Arthur Dent")

Check out more examples or hear about how Fabric.app uses R.swift!

Demo

Autocompleted images:

Compiletime checked images:

This is only the beginning, check out more examples!

CocoaHeadsNL presentation

Mathijs Kadijk presented R.swift at the September 2016 CocoaHeadsNL meetup. Talking about the ideas behind R.swift and demonstrating how to move from plain stringly-typed iOS code to statically typed code.

Features

After installing R.swift into your project you can use the R-struct to access resources. If the struct is outdated just build and R.swift will correct any missing/changed/added resources.

R.swift currently supports these types of resources:

• Images
• Fonts
• Resource files
• Colors
• Localized strings
• Storyboards
• Segues
• Nibs
• Reusable cells

Runtime validation with R.validate():

• If all images used in storyboards and nibs are available
• If all named colors used in storyboards and nibs are available
• If all view controllers with storyboard identifiers can be loaded
• If all custom fonts can be loaded

Q&A

• Why was R.swift created?
• Why should I choose R.swift over alternative X or Y?
• What are the requirements to run R.swift?
• How to use methods with a Void argument?
• How to fix missing imports in the generated file?
• How to use classes with the same name as their module?
• Can I ignore resources?
• Can I use R.swift in a library?
• How does R.swift work?
• How to upgrade to a new major version?

Installation

CocoaPods is the recommended way of installation, as this avoids including any binary files into your project.

Note on Carthage: R.swift is a tool used in a build step, it is not a dynamic library. Therefore it is not possible to install it with Carthage.

⚠️ Change between R.swift 3 and R.swift 4

Be aware:
For R.swift 3.x and below, the rswift executable should be called with only one argument: rswift $SRCROOT
For R.swift 4, the rswift executable should be called with two arguments: rswift generate $SRCROOT

CocoaPods (recommended)

There is also a short video of this instruction.

1. Add pod 'R.swift' to your Podfile and run pod install
2. In Xcode: Click on your project in the file list, choose your target under TARGETS, click the Build Phases tab and add a New Run Script Phase by clicking the little plus icon in the top left
3. Drag the new Run Script phase above the Compile Sources phase and below Check Pods Manifest.lock, expand it and paste the following script:

   "$PODS_ROOT/R.swift/rswift" generate "$SRCROOT"
   

4. Build your project, in Finder you will now see a R.generated.swift in the $SRCROOT-folder, drag the R.generated.swift files into your project and uncheck Copy items if needed

Tip: Add the *.generated.swift pattern to your .gitignore file to prevent unnecessary conflicts.

Manually

0. Add the R.swift.Library to your project
1. Download a R.swift release, unzip it and put it into your source root directory
2. In Xcode: Click on your project in the file list, choose your target under TARGETS, click the Build Phases tab and add a New Run Script Phase by clicking the little plus icon in the top left
3. Drag the new Run Script phase above the Compile Sources phase, expand it and paste the following script:

   "$SRCROOT/rswift" generate "$SRCROOT"
   

4. Build your project, in Finder you will now see a R.generated.swift in the $SRCROOT-folder, drag the R.generated.swift files into your project and uncheck Copy items if needed

Tip: Add the *.generated.swift pattern to your .gitignore file to prevent unnecessary conflicts.

Building from source

R.swift is built using Swift Package Manager (SPM).

1. Check out the code
2. Run swift build -c release -Xswiftc -static-stdlib from the root directory
3. Follow the manual installation steps with the binary you now have

For developing on R.swift in Xcode, run swift package generate-xcodeproj --xcconfig-overrides RswiftConfig.xcconfig.

Contribute

We'll love contributions, read the contribute docs for info on how to report issues, submit ideas and submit pull requests!

License

R.swift and R.swift.Library are created by Mathijs Kadijk and released under a MIT License.

Special thanks to Tom Lokhorst for his major contributions and help maintaining this project.