Carthage

Carthage is intended to be the simplest way to add frameworks to your Cocoa application.

The basic workflow looks something like this:

1. Create a Cartfile that lists the frameworks you’d like to use in your project.
2. Run Carthage, which fetches and builds each framework you’ve listed.
3. Drag the built .framework binaries into your application’s Xcode project.

Carthage builds your dependencies and provides you with binary frameworks, but you retain full control over your project structure and setup. Carthage does not automatically modify your project files or your build settings.

Differences between Carthage and CocoaPods

CocoaPods is a long-standing dependency manager for Cocoa. So why was Carthage created?

Firstly, CocoaPods (by default) automatically creates and updates an Xcode workspace for your application and all dependencies. Carthage builds framework binaries using xcodebuild, but leaves the responsibility of integrating them up to the user. CocoaPods’ approach is easier to use, while Carthage’s is flexible and unintrusive.

The goal of CocoaPods is listed in its README as follows:

… to improve discoverability of, and engagement in, third party open-source libraries, by creating a more centralized ecosystem.

By contrast, Carthage has been created as a decentralized dependency manager. There is no central list of projects, which reduces maintenance work and avoids any central point of failure. However, project discovery is more difficult—users must resort to GitHub’s Trending pages or similar.

CocoaPods projects must also have what’s known as a podspec file, which includes metadata about the project and specifies how it should be built. Carthage uses xcodebuild to build dependencies, instead of integrating them into a single workspace, it doesn’t have a similar specification file but your dependencies must include their own Xcode project that describes how to build their products.

Ultimately, we created Carthage because we wanted the simplest tool possible—a dependency manager that gets the job done without taking over the responsibility of Xcode, and without creating extra work for framework authors. CocoaPods offers many amazing features that Carthage will never have, at the expense of additional complexity.

Installing Carthage

There are multiple options for installing Carthage:

• Installer: Download and run the Carthage.pkg file for the latest release, then follow the on-screen instructions.

• Homebrew: You can use Homebrew and install the carthage tool on your system simply by running brew update and brew install carthage. (note: if you previously installed the binary version of Carthage, you should delete /Library/Frameworks/CarthageKit.framework).

• From source: If you’d like to run the latest development version (which may be highly unstable or incompatible), simply clone the master branch of the repository, then run make install. Requires Xcode 8.2 (Swift 3.0.2).

Adding frameworks to an application

Once you have Carthage installed, you can begin adding frameworks to your project. Note that Carthage only supports dynamic frameworks, which are only available on iOS 8 or later (or any version of OS X).

Getting started

If you're building for OS X

1. Create a Cartfile that lists the frameworks you’d like to use in your project.
2. Run carthage update. This will fetch dependencies into a Carthage/Checkouts folder and build each one or download a pre-compiled framework.
3. On your application targets’ “General” settings tab, in the “Embedded Binaries” section, drag and drop each framework you want to use from the Carthage/Build folder on disk.

Additionally, you'll need to copy debug symbols for debugging and crash reporting on OS X.

1. On your application target’s “Build Phases” settings tab, click the “+” icon and choose “New Copy Files Phase”.
2. Click the “Destination” drop-down menu and select “Products Directory”.
3. For each framework you’re using, drag and drop its corresponding dSYM file.

If you're building for iOS, tvOS, or watchOS

1. Create a Cartfile that lists the frameworks you’d like to use in your project.
2. Run carthage update. This will fetch dependencies into a Carthage/Checkouts folder, then build each one or download a pre-compiled framework.
3. On your application targets’ “General” settings tab, in the “Linked Frameworks and Libraries” section, drag and drop each framework you want to use from the Carthage/Build folder on disk.
4. On your application targets’ “Build Phases” settings tab, click the “+” icon and choose “New Run Script Phase”. Create a Run Script in which you specify your shell (ex: /bin/sh), add the following contents to the script area below the shell:

/usr/local/bin/carthage copy-frameworks

and add the paths to the frameworks you want to use under “Input Files”, e.g.:

$(SRCROOT)/Carthage/Build/iOS/Box.framework
$(SRCROOT)/Carthage/Build/iOS/Result.framework
$(SRCROOT)/Carthage/Build/iOS/ReactiveCocoa.framework

This script works around an App Store submission bug triggered by universal binaries and ensures that necessary bitcode-related files and dSYMs are copied when archiving.

With the debug information copied into the built products directory, Xcode will be able to symbolicate the stack trace whenever you stop at a breakpoint. This will also enable you to step through third-party code in the debugger.

When archiving your application for submission to the App Store or TestFlight, Xcode will also copy these files into the dSYMs subdirectory of your application’s .xcarchive bundle.

For both platforms

Along the way, Carthage will have created some build artifacts. The most important of these is the Cartfile.resolved file, which lists the versions that were actually built for each framework. Make sure to commit your Cartfile.resolved, because anyone else using the project will need that file to build the same framework versions.

Swift binary framework download compatibility

Carthage will check to make sure that downloaded Swift (and mixed Objective-C/Swift) frameworks were built with the same version of Swift that is in use locally. If there is a version mismatch, Carthage will proceed to build the framework from source. If the framework cannot be built from source, Carthage will fail.

Because Carthage uses the output of xcrun swift --version to determine the local Swift version, make sure to run Carthage commands with the Swift toolchain that you intend to use. For many use cases, nothing additional is needed. However, for example, if you are building a Swift 2.3 project using Xcode 8.x, one approach to specifying your default swift for carthage bootstrap is to use the following command:

TOOLCHAINS=com.apple.dt.toolchain.Swift_2_3 carthage bootstrap

Running a project that uses Carthage

After you’ve finished the above steps and pushed your changes, other users of the project only need to fetch the repository and run carthage bootstrap to get started with the frameworks you’ve added.

Adding frameworks to unit tests or a framework

Using Carthage for the dependencies of any arbitrary target is fairly similar to using Carthage for an application. The main difference lies in how the frameworks are actually set up and linked in Xcode.

Because unit test targets are missing the “Linked Frameworks and Libraries” section in their “General” settings tab, you must instead drag the built frameworks to the “Link Binaries With Libraries” build phase.

In the Test target under the "Build Settings" tab, add @loader_path/Frameworks to the "Runpath Search Paths" if it isn't already present.

In rare cases, you may want to also copy each dependency into the build product (e.g., to embed dependencies within the outer framework, or make sure dependencies are present in a test bundle). To do this, create a new “Copy Files” build phase with the “Frameworks” destination, then add the framework reference there as well.

Upgrading frameworks

If you’ve modified your Cartfile, or you want to update to the newest versions of each framework (subject to the requirements you’ve specified), simply run the carthage update command again.

If you only want to update one , or specific, dependencies, pass them as a space-separated list to the update command. e.g.

carthage update Box

or

carthage update Box Result

Nested dependencies

If the framework you want to add to your project has dependencies explicitly listed in a Cartfile, Carthage will automatically retrieve them for you. You will then have to drag them yourself into your project from the Carthage/Build folder.

If the embedded framework in your project has dependencies to other frameworks you must link them to application target (even if application target does not have dependency to that frameworks and never uses them).

Using submodules for dependencies

By default, Carthage will directly check out dependencies’ source files into your project folder, leaving you to commit or ignore them as you choose. If you’d like to have dependencies available as Git submodules instead (perhaps so you can commit and push changes within them), you can run carthage update or carthage checkout with the --use-submodules flag.

When run this way, Carthage will write to your repository’s .gitmodules and .git/config files, and automatically update the submodules when the dependencies’ versions change.

Automatically rebuilding dependencies

If you want to work on your dependencies during development, and want them to be automatically rebuilt when you build your parent project, you can add a Run Script build phase that invokes Carthage like so:

/usr/local/bin/carthage build --platform "$PLATFORM_NAME" --project-directory "$SRCROOT"

Note that you should be using submodules before doing this, because plain checkouts should not be modified directly.

Caching builds

By default Carthage will rebuild a dependency regardless of whether it's the same resolved version as before. Passing the --cache-builds will cause carthage to avoid rebuilding a dependency if it can. See information on version files for details on how carthage performs this caching.

Note: At this time --cache-builds is incompatible with --use-submodules. Using both will result in working copy and committed changes to your submodule dependency not being correctly rebuilt. See #1785 for details.

Bash/Zsh/Fish completion

Auto completion of Carthage commands and options are available as documented in Bash/Zsh/Fish Completion.

Supporting Carthage for your framework

Carthage only officially supports dynamic frameworks. Dynamic frameworks can be used on any version of OS X, but only on iOS 8 or later.

Because Carthage has no centralized package list, and no project specification format, most frameworks should build automatically.

The specific requirements of any framework project are listed below.

Share your Xcode schemes

Carthage will only build Xcode schemes that are shared from your .xcodeproj. You can see if all of your intended schemes build successfully by running carthage build --no-skip-current, then checking the Carthage/Build folder.

If an important scheme is not built when you run that command, open Xcode and make sure that the scheme is marked as “Shared,” so Carthage can discover it.

Resolve build failures

If you encounter build failures in carthage build --no-skip-current, try running xcodebuild -scheme SCHEME -workspace WORKSPACE build or xcodebuild -scheme SCHEME -project PROJECT build (with the actual values) and see if the same failure occurs there. This should hopefully yield enough information to resolve the problem.

If you have multiple versions of the Apple developer tools installed (an Xcode beta, for example), use xcode-select to change which version Carthage uses.

If you’re still not able to build your framework with Carthage, please open an issue and we’d be happy to help!

Tag stable releases

Carthage determines which versions of your framework are available by searching through the tags published on the repository, and trying to interpret each tag name as a semantic version. For example, in the tag v1.2, the semantic version is 1.2.0.

Tags without any version number, or with any characters following the version number (e.g., 1.2-alpha-1) are currently unsupported, and will be ignored.

Archive prebuilt frameworks into one zip file

Carthage can automatically use prebuilt frameworks, instead of building from scratch, if they are attached to a GitHub Release on your project’s repository or via a binary project definition file.

To offer prebuilt frameworks for a specific tag, the binaries for all supported platforms should be zipped up together into one archive, and that archive should be attached to a published Release corresponding to that tag. The attachment should include .framework in its name (e.g., ReactiveCocoa.framework.zip), to indicate to Carthage that it contains binaries.

You can perform the archiving operation above with the carthage archive command as follows:

carthage build --no-skip-current
carthage archive YourFrameworkName

Draft Releases will be automatically ignored, even if they correspond to the desired tag.

Use travis-ci to upload your tagged prebuild frameworks

It is possible to use travis-ci in order to build and upload your tagged releases.

1. Install travis CLI with gem install travis

2. Setup travis-ci for your repository (Steps 1 and 2)

3. Create .travis.yml file at the root of your repository based on that template. Set FRAMEWORK_NAME to the correct value.

   Replace PROJECT_PLACEHOLDER and SCHEME_PLACEHOLDER

   If you are using a workspace instead of a project remove the xcode_project line and uncomment the xcode_workspace line.

   The project should be in the format: MyProject.xcodeproj

   The workspace should be in the format: MyWorkspace.xcworkspace

   Feel free to update the xcode_sdk value to another SDK, note that testing on iphoneos SDK would require you to upload a code signing identity

   For more informations you can visit travis docs for objective-c projects

   language: objective-c
   osx_image: xcode7.3
   xcode_project: <PROJECT_PLACEHOLDER>
   # xcode_workspace: <WORKSPACE_PLACEHOLDER>
   xcode_scheme: <SCHEME_PLACEHOLDER>
   xcode_sdk: iphonesimulator9.3
   env:
     global:
       - FRAMEWORK_NAME=<THIS_IS_A_PLACEHOLDER_REPLACE_ME>
   before_install:
     - brew update
     - brew outdated carthage || brew upgrade carthage
   before_script:
     # bootstrap the dependencies for the project
     # you can remove if you don't have dependencies
     - carthage bootstrap
   before_deploy:
     - carthage build --no-skip-current
     - carthage archive $FRAMEWORK_NAME

4. Run travis setup releases, follow documentation here

   This command will encode your github credentials into the .travis.yml file in order to let travis upload the release to github.com When prompted for the file to upload, enter $FRAMEWORK_NAME.framework.zip

5. Update the deploy section to run on tags:

   In .travis.yml locate:

   on:
     repo: repo/repo

   And add tags: true and skip_cleanup: true:

   skip_cleanup: true
   on:
     repo: repo/repo
     tags: true

   That will let travis know to create a deployment when a new tag is pushed and prevent travis to cleanup the generated zip file

Build static frameworks to speed up your app’s launch times

If you embed many dynamic frameworks into your app, its pre-main launch times may be quite slow. Carthage is able to help mitigate this by building your dynamic frameworks as static frameworks instead. Static frameworks can be linked directly into your application or merged together into a larger dynamic framework with a few simple modifications to your workflow, which can result in dramatic reductions in pre-main lauch times. See the StaticFrameworks doc for details.

Please note that a few caveats apply to this approach:

• Swift static frameworks are not officially supported by Apple
• This is an advanced workflow that is not built into Carthage, YMMV

Declare your compatibility

Want to advertise that your project can be used with Carthage? You can add a compatibility badge:

… to your README, by simply inserting the following Markdown:

[![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)

Known issues

DWARFs symbol problem

Pre-built framework cannot be debugged using step execution on other machine than on which the framework was built. Simply carthage bootstrap/build/update --no-use-binaries should fix this, but for more automated workaround, see #924. Dupe rdar://23551273 if you want Apple to fix the root cause of this problem.

CarthageKit

Most of the functionality of the carthage command line tool is actually encapsulated in a framework named CarthageKit.

If you’re interested in using Carthage as part of another tool, or perhaps extending the functionality of Carthage, take a look at the CarthageKit source code to see if the API fits your needs.

License

Carthage is released under the MIT License.

Header backdrop photo is released under the CC BY-NC-SA 2.0 license. Original photo by Richard Mortel.