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xcres searches your Xcode project for resourcesand generates an index as struct constants.



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~> 0.6.3
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< 2.0, >= 1.2.0
 Project Readme


Twitter: @mrackwitz Gem Build Status Code Climate Inline Docs

xcres searches your Xcode project for resources and generates an index as struct constants. So you will never have to reference a resource, without knowing already at compile time if it exists or not.

It includes loose images, .bundles, asset catalogs (.xcasset) and even .strings in the index.

It gives you code autocompletion for resources and localized string keys, without the need of an Xcode plugin.

Especially if your app is a bit more complex, this will greatly improve your workflow. It ensures a better quality and gives you more safety. You will see directly when a resource is missing, when you renamed it, or you moved it around.

Furthermore it won't even bother you for trivial name changes like change capitalization or converting name scheme from train-case or snake_case to camelCase and vice versa.

It will warn you in Xcode on build, if certain resources or string keys can't be referenced, because their name contain invalid chars, duplicates in the camelCase variant with another key, or would be equal to a protected compiler keyword.

The generated index could look like below.

xcres can generate code both as Swift or Objective-C. If you are using both in your project choose Objective-C and add an import to the generated header to your project's bridging header.


public class R {
    public enum Images: String {
        /// doge.jpeg
        case doge = "doge.jpeg"
    public enum ImagesAssets: String {
        /// AppIcon
        case app = "AppIcon"
        /// LaunchImage
        case launch = "LaunchImage"
        /// DefaultAvatar
        case defaultAvatar = "DefaultAvatar"
    public enum Strings: String {
        /// Title shown if a wrong password was entered.
        case errorTitleWrongPassword = "error_title_wrong_password"
        /// Message shown if a wrong password was entered.
        case errorMessageWrongPassword = "error_message_wrong_password"


FOUNDATION_EXTERN const struct R {
    struct Images {
        /// doge.jpeg
        __unsafe_unretained NSString *doge;
    } Images;
    struct ImagesAssets {
        /// AppIcon
        __unsafe_unretained NSString *app;
        /// LaunchImage
        __unsafe_unretained NSString *launch;
        /// DefaultAvatar
        __unsafe_unretained NSString *defaultAvatar;
    } ImagesAssets;
    struct Strings {
        /// Password wrong!
        __unsafe_unretained NSString *errorTitleWrongPassword;
        /// Please enter the correct password.
        __unsafe_unretained NSString *errorMessageWrongPassword;
    } Strings;
} R;


xcres is built with Ruby and it will be installable with the default Ruby available on OS X. You can use a Ruby Version manager, if you know what you're doing. Using the default Ruby install will require you to use sudo when installing gems. (This is only an issue for the duration of the gem installation, though.)

Install the gem on your machine:

$ [sudo] gem install xcres

Use the automatic integration to add a build phase to your project, by executing the following command:


$ xcres install --swift


$ xcres install


Reference your resources safely with the generated constants.

Asset Catalogs

Assuming your asset catalog is named Images.xcassets.
xcres supports multiple bundles in one project.

Instead of:

[UIImage imageNamed:@"PersonDefaultAvatar"]

Just write:

[UIImage imageNamed:R.ImagesAssets.personDefaultAvatar]
How to Add a New Resource
  1. Add it to your asset catalog.
  • Trigger a build. (⌘ + B)
  • The new key will be available under R.${catalogName}Assets.${keyName:camelCase} and is ready for use in your code now.

Loose Images

Instead of:

[UIImage imageNamed:@"table_header_background_image"]

Just write:

[UIImage imageNamed:R.Images.tableHeaderBackgroundImage]
How to Add a New Loose Image
  1. Drop the image in your project.
  • Trigger a build. (⌘ + B)
  • The new key will be available under R.Images.${keyName:camelCase} and is ready for use in your code now.


Instead of:

NSLocalizedString(@"error_message_wrong_password", @"Message shown if a wrong password was entered.")

Just write:




NSLocalizedString(R.Strings.errorMessageWrongPassword, @"Message shown if a wrong password was entered.")
How to Add a New String

With xcres your workflow for adding new strings will change slightly.

  1. Create a new string (at least) in your project's native development language in one of the strings files included in your target. (By default this will be en.lproj/Localizable.strings)
  • Trigger a build. (⌘ + B)
  • The new key will be available under R.Strings.${keyName:camelCase} and is ready for use in your code now.

Known Issues & Tips

One minor drawback is that genstrings will not be helpful anymore. But this tool is mostly useful in the first step, when bootstrapping your project, until you care about internationalization and want to provide translations.

xcres generally assumes that you don't use natural language for keys, as this will led very fast to ambiguities. It will filter out unwanted chars when transforming your keys to camel case notation, but it will also warn you about those. It can be a help, if you want to migrate your project to non-natural language keys.


The logo was designed by @kuchengnom. Swift support was implemented by @timbodeit.


xcres is available under MIT License. See the LICENSE file for more info.