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Contributing code to Matrix

Please read https://github.com/matrix-org/synapse/blob/master/CONTRIBUTING.md.

Element iOS support can be found in this room: Element X iOS Matrix room #element-x-ios:matrix.org

Setting up a development environment

Setup Project

It's mandatory to have homebrew installed on your mac, and run after the checkout:

swift run tools setup-project

This will:

  • Install various brew dependencies required for the project (like xcodegen).
  • Set up git to use the shared githooks from the repo, instead of the default ones.
  • Automatically run xcodegen for the first time.


We suggest using an Xcode version later than 15.0.1.

The Xcode project can be directly compiled through the shared ElementX scheme which includes the main application as well as the unit and UI tests.

The Xcode project itself is generated through xcodegen so any changes shouldn't be made directly to it but to the configuration files.


Dependencies will be automatically fetched through the Swift Package Manager, including a release version of the MatrixRustSDK. If you encounter issues while resolving the package graph please attempt a cache reset through File -> Packages -> Reset Package Caches.

To setup the RustSDK in local development mode run the following command

swift run tools build-sdk

This will clone a copy of the SDK if needed, build it for all supported architectures and configure ElementX to use the built framework. To learn about additional options run

swift run tools build-sdk --help


The project depends on some tools for the build process. These are all included in the Brewfile and can be easily installed by running

brew bundle

Git LFS is used to store UI test snapshots. swift run tools setup-project will already install it, however it can also be installed after a checkout by running:

git lfs install
ln -s "$(which git-lfs)" "$(git --exec-path)/git-lfs"

Snapshot Tests

If you make changes to the UI you may cause existing UI Snapshot tests to fail. You can run the snapshot tests using UITests target. To update the reference snapshots, delete them from element-x-ios/UITests/Sources/__Snapshots__/Application and run the tests again. These are the devices we store snapshots for that you will need to run against which need to use the iOS 16.4 simulator in en-US for consistency:

  • iPhone 14
  • iPad (9th generation)


The project uses its own shared githooks stored in the .githooks folder, you will need to configure git to use such folder, this is already done if you have run the setup tool with swift run tools setup-project otherwise you would need to run:

git config core.hooksPath .githooks

Strings and Translations

The project uses Localazy and is sharing its translations with the ElementX Android project: https://localazy.com/p/element

Please read the Android docs for more information about how this works. Note: On iOS we don't have the additional step of filtering strings per module.

Continuous Integration

ElementX uses Fastlane for running actions on the CI and tries to keep the configuration confined to either fastlane or xcodegen.

Please run bundle exec fastlane to see available options.

Network debugging proxy

It's possible to debug the app's network traffic with a proxy server by setting the HTTPS_PROXY environment variable in the ElementX scheme to the proxy's address (e.g. localhost:8080 for mitmproxy).

Pull requests

Please see our pull request guide.

Implementing a new screen

New screen flows are currently using the MVVM-Coordinator pattern. Please refer to the create screen template section.


All changes, even minor ones, need a corresponding changelog / newsfragment entry. These are managed by Towncrier.

To create a changelog entry, make a new file in the changelog.d directory named in the format of ElementXiOSIssueNumber.type. The type can be one of the following:

  • feature for a new feature
  • change for updates to an existing feature
  • bugfix for bug fix
  • api for an api break
  • i18n for translations
  • build for changes related to build, tools, CI/CD
  • doc for updates to the documentation
  • wip for anything that isn't ready to ship and will be enabled at a later date
  • misc for other changes

This file will become part of our changelog at the next release, so the content of the file should be a short description of your change in the same style as the rest of the changelog. The file must only contain one line. It can contain Markdown formatting. It should start with the area of the change (screen, module, ...) and end with a full stop (.) or an exclamation mark (!) for consistency.

Adding credits to the changelog is encouraged, we value your contributions and would like to have you shouted out in the release notes!

For example, a fix for an issue #1234 would have its changelog entry in changelog.d/1234.bugfix, and contain content like:

Voice Messages: Fix a crash when sending a voice message. Contributed by Jane Matrix.

If there are multiple pull requests involved in a single bugfix/feature/etc, then the content for each changelog.d file should be the same. Towncrier will merge the matching files together into a single changelog entry when we come to release.

There are exceptions on the ElementXiOSIssueNumber.type entry format. Even if it is not encouraged, you can use:

  • pr-[PRNumber].type for a PR with no related issue
  • x-nolink-[AnyNumber].type for a PR with a change entry that will not have a link automatically appended. It must be used for internal project update only. AnyNumber should be a value that does not clash with existing files.

To preview the changelog for pending changelog entries, use:

$ towncrier build --draft --version 1.2.3

Coding style

For Swift coding style we use SwiftLint to check some conventions at compile time (rules are located in the .swiftlint.yml file). Otherwise please have a look to Apple Swift conventions. We are also using some of the conventions of raywenderlich.com Swift style guide.

We enforce the coding style by running checks on the CI for every PR through Danger, SwiftLint, SwiftFormat and SonarCloud

We also gather coverage reports on every PR through Codecov and will eventually start enforcing minimums.


Thank your for contributing to Matrix projects!