Multiplatform Swift Package

This is a Gradle plugin for Kotlin Multiplatform projects that generates an XCFramework for your native Apple targets and creates a matching Package.swift file to distribute it as a binary target.

To distribute the framework a ZIP file containing it will be created and referenced from the Package. You can upload the ZIP file to your package registry so that SPM can download it.

Prerequisites

• XCode version 12.0+
• Gradle version 6.0+

Installing

The plugin is published on Maven central. Add it to the plugins block in the Gradle build file.

// build.gradle.kts
plugins {
  // projects targeting kotlin >=1.8.0
  id("io.github.luca992.multiplatform-swiftpackage") version "2.2.2"
}

Execution

The plugin adds two Gradle tasks to your project.

• ./gradlew createSwiftPackage

  Creates the XCFramework, ZIP file and Package.swift

• ./gradlew createXCFramework

  Creates only the XCFramework

Configuration

Generation of the Package and XCFramework can be configured using the plugin's DSL. Add the configuration to the Gradle build file.

This is a complete example of the required configuration. All available options will be explained in the following sections.

multiplatformSwiftPackage {
    swiftToolsVersion("5.3")
    targetPlatforms {
      iOS { v("13") }
    }
}

Package Name

By default, the name of the Swift package will be the base name of the first framework found in the project. However, you can declare a different name for the package. This might be useful if your frameworks have different base names, and you want your package to have a common name.

packageName("MyAwesomeKit")

Hint: If the cocoapods plugin is applied the name of the package will default to the value assigned to the frameworkName property. Otherwise, the value of the baseName property of the framework configuration will be used.

Output Directory

By default, the plugin will write all files into the swiftpackage folder in the project directory. You can configure the output folder by providing a File object pointing to it.

outputDirectory(File(projectDir, "swiftpackage"))

Swift Tools Version

The first line of every Package.swift file is a header declaring the Swift tools version required by the package. To set the version use the following configuration and provide the version your XCode project supports.

swiftToolsVersion("5.3")

Distribution Mode

Swift packages can distribute binary targets either via the local file system or via a remote ZIP file. Depending on your requirements (e.g. local development or CI) use one of the following configurations.

Local distribution

distributionMode { local() }

Remote distribution

Provide a URL where the ZIP file containing the XCFramework is located. This should point to the root directory and not to the ZIP file itself.

// correct
distributionMode { remote("https://example.com") }

// wrong
distributionMode { remote("https://example.com/MyLib.zip") }

ZIP File Name

By default, the name of the generated ZIP file consists of the package name concatenated with the project's version. You can configure the name by setting a custom value. The .zip file extension will be added during the build and should be omitted here.

zipFileName("MyAwesomeKit")

Build Configuration

Apple frameworks can be built with different configurations. By default, these are release and debug. However, you can also create your own configurations.

Default

buildConfiguration { release() }
// or
buildConfiguration { debug() }

Custom

buildConfiguration { named("staging") }

Target Platforms

The main feature of an XCFramework is packaging multiple architectures for the same platform. This is great since it allows distributing e.g. iOS builds for both the physical device, and the simulator in one package.

Swift packages require declaring the minimum supported version for each platform. Therefore, you need to configure both the architectures for each platform and the version.

You can either declare all target architectures specifically or add all architectures of a platform at once.

targetPlatforms {
  // all iOS targets (== device and simulator) with minimum version 13
  iOS { v("13") }

  // macOS with minimum version 10.0
  targets("macosX64") { v("10.0") }
}

Note: If you are using Groovy for the build script the target names must be passed as a list.

targetPlatforms {
  // the catch-all DSL works the same in Groovy and Kotlin
  iOS { v("13") }

  // however, Groovy requires a list when the targets() DSL is used
  targets(['macosX64']) { v('10.0') }
}

Available platform shortcuts are:

• iOS { v("xxx") }
• tvOS { v("xxx") }
• macOS { v("xxx") }
• watchOS { v("xxx") }

Further Reading

To learn more about the Swift Package Manager I recommend reading the following resources.

• https://swift.org/package-manager/
• https://github.com/apple/swift-package-manager
• https://docs.swift.org/package-manager/PackageDescription/PackageDescription.html

License

Copyright 2020 Georg Dresler

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.