ProjectDescriptionHelpers

This feature allows you to reuse code between manifests.

Overview

All Swift files in the Geko/ProjectDescriptionHelpers/ folder are compiled into a module called ProjectDescriptionHelpers, which can be imported into all manifests except Config.swift and Plugin.swift. Sharing code is useful to avoid duplications and ensure consistency across the projects.

TIP

In the ProjectDescriptionHelpers folder you can import the standard Swift libraries, ProjectDescription and ProjectDescriptionHelpers Plugins.

// Geko/ProjectDescriptionHelpers/SharedCode.swift
import ProjectDescription

public struct SharedCode {
    public let product: Product

    public init(product: Product) {
        self.product = product
    }
}

// Project.swift
import ProjectDescription
import ProjectDescriptionHelpers

let sharedCode = SharedCode(product: .framework)

let project = Project(
    ...
    product: sharedCode.product,
    ...
)

Being able to reuse project definitions is useful for the following reasons:

• It eases the maintenance because changes can be applied in one place and all the projects get the changes automatically.
• It makes it possible to define conventions that new projects can conform to.
• Projects are more consistent and therefore the likelihood of broken builds due inconsistencies is significantly less.
• Adding a new projects becomes an easy task because we can reuse the existing logic.

Examples

Project setup templates

The snippets below contain an example of how we extend the Project model to add static constructors and how we use them from a Project.swift file:

// Geko/ProjectDescriptionHelpers/Project+Templates.swift
import ProjectDescription

extension Project {
  public static func featureFramework(name: String, dependencies: [TargetDependency] = []) -> Project {
    return Project(
        name: name,
        targets: [
            Target(
                name: name,
                destinations: .iOS,
                product: .framework,
                bundleId: "io.geko.\(name)",
                infoPlist: "\(name).plist",
                sources: ["Sources/\(name)/**"],
                resources: ["Resources/\(name)/**",],
                dependencies: dependencies
            ),
            Target(
                name: "\(name)Tests",
                destinations: .iOS,
                product: .unitTests,
                bundleId: "io.geko.\(name)Tests",
                infoPlist: "\(name)Tests.plist",
                sources: ["Sources/\(name)Tests/**"],
                resources: ["Resources/\(name)Tests/**",],
                dependencies: [.target(name: name)]
            )
        ]
    )
  }
}

// Project.swift
import ProjectDescription
import ProjectDescriptionHelpers

let project = Project.featureFramework(name: "MyFeature")

Typing of environment variables

The example below shows how you can define a static variable in Geko/ProjectDescriptionHelpers and reuse it in Workspace.swift to enable or disable the Workspace Mapper Plugin depending on the environment.

// Env+Extension.swift
import ProjectDescription

public extension Env {
    static let isCI = {
        Env.bool("CI") ?? false
    }()
    // ...
}

// Workspace.swift
import ProjectDescription
import ProjectDescriptionHelpers
import ImpactAnalysis

func pluginGenerateSharedTestTarget() -> WorkspaceMapper? {
    guard Env.isCI else { return nil }

    return WorkspaceMapper(
        name: "ImpactAnalysis", 
        params: [:]
    )
}

func workspaceMappers() -> [WorkspaceMapper] {
    var mappers: [WorkspaceMapper] = []

    if let sharedTarget = pluginGenerateSharedTestTarget() {
        mappers.append(sharedTarget)
    }

    return mappers
}

let workspace = Workspace(
    // ...
    workspaceMappers: workspaceMappers()
    // ...
)