Migrate an XcodeGen project

XcodeGen is a project-generation tool that uses YAML as a configuration format to define Xcode projects. Many organizations adopted it trying to escape from the frequent Git conflicts that arise when working with Xcode projects. However, frequent Git conflicts is just one of the many problems that organizations experience. Xcode exposes developers with a lot of intricacies and implicit configurations that make it hard to maintain and optimize projects at scale. XcodeGen falls short there by design because it's a tool that generates Xcode projects, not a project manager. If you need a tool that helps you beyond generating Xcode projects, you might want to consider Tuist.

SWIFT OVER YAML

Many organizations prefer Tuist as a project generation tool too because it uses Swift as a configuration format. Swift is a programming language that developers are familiar with, and that provides them with the convenience of using Xcode's autocompletion, type-checking, and validation features.

What follows are some considerations and guidelines to help you migrate your projects from XcodeGen to Tuist.

Project generation

Both Tuist and XcodeGen provide a generate command that turns your project declaration into Xcode projects and workspaces.

XcodeGen

xcodegen generate

Tuist

tuist generate

The difference lays in the editing experience. With Tuist, you can run the tuist edit command, which generates an Xcode project on the fly that you can open and start working on. This is particularly useful when you want to make quick changes to your project.

project.yaml

XcodeGen's project.yaml description file becomes Project.swift. Moreover, you can have Workspace.swift as a way to customize how projects are grouped in workspaces. You can also have a project Project.swift with targets that reference targets from other projects. In those cases, Tuist will generate an Xcode Workspace including all the projects.

XcodeGen directory structure

/
  project.yaml

Tuist directory structure

/
  Tuist.swift
  Project.swift
  Workspace.swift

XCODE'S LANGUAGE

Both XcodeGen and Tuist embrace Xcode's language and concepts. However, Tuist's Swift-based configuration provides you with the convenience of using Xcode's autocompletion, type-checking, and validation features.

Spec templates

One of the disadvantages of YAML as a language for project configuration is that it doesn't support reusability across YAML files out of the box. This is a common need when describing projects, which XcodeGen had to solve with their own propietary solution named "templates". With Tuist's re-usability is built into the language itself, Swift, and through a Swift module named project description helpers, which allow reusing code across all your manifest files.

Tuist/ProjectDescriptionHelpers/Target+Features.swift

import ProjectDescription

extension Target {
  /**
    This function is a factory of targets that together represent a feature.
  */
  static func featureTargets(name: String) -> [Target] {
    // ...
  }
}

Project.swift

import ProjectDescription
import ProjectDescriptionHelpers

let project = Project(name: "MyProject",
                      targets: Target.featureTargets(name: "MyFeature"))