Developing with Xcode IDE

We will refer to Xcode as the Integrated Development Environment (IDE) for developing source code. Every other aspect of Xcode is outside the scope of this chapter. The plugin focuses heavily on keeping the developer experience within the IDE as close as possible to the vanilla experience to ensure happiness among developers. For example, executing tests from the sidebar, cmd+click navigation, searching symbols are all considered and work as expected. We will discuss the background of the choices made by the plugin.

The Xcode IDE plugin assumes a unidirectional transfer of the build knowledge, from Gradle to Xcode. In this case, Gradle is the single source of truth, and it convert only the required information into an Xcode-compatible model. Whenever possible, the generated Xcode IDE will delegate to Gradle. Gradle being the most flexible it allows for complex wiring of tasks and dependencies.

The developer must generate Xcode IDE files. The files shouldn’t be committed to source control.

The plugin also assumes a single workspace per Gradle multi-project build. Each Gradle project can contribute more than one Xcode project to the workspace if required. For this reason, the plugin registers an extended extension on the root Gradle project to provide the additional capability for generating a workspace.

By default, the Xcode IDE plugin considers a one-to-one mapping of the Gradle project to the Xcode project. Despite this mapping, it is possible to register additional Xcode project via the container available on the extension. The plugin includes the source code to the project matching a group named after the target it’s associated. The plugin disregards the on-disk layout of the sources when adding them to the project groups.

The Gradle build configuration is easily accessible from the IDE. Despite Xcode having no support for Gradle file type, the Xcode IDE plugin includes them in the main group of the generated Xcode project as shown in the picture below. The plugin also includes the gradle.properties files, if available, as well as any explicit initialization scripts passed on the command line. It also considers changes to the setting and build file locations.

The plugins consider a one-to-one mapping between the Gradle project components to Xcode targets. Each target registered to an Xcode project will delegate to Gradle. By default, the plugin infers the product type from the Gradle component type. For ad-hoc Xcode projects, it is possible to choose product types that can be unknown to Xcode. The external build target offers less constraint than native Xcode targets allowing better integration with Gradle.

Xcode IDE has a process to understand the sources to provide code assistance features such as syntax highlighting, code completion, and search for definitions and references. The plugin will create an additional indexer target identified by the __indexer_ prefix for each product type it known as indexable. Those targets are configured by the plugin to ensure the code is appropriately indexed. In general, the plugin will source the indexer’s build settings from the original target. Some indexable product type requires special attention to play well with Xcode. The plugin may have specialized logic to ensure the generated indexer target works with Xcode’s indexer. You should never use any of those targets while developing inside the Xcode IDE.

A build configuration is analogous to a build type in Gradle, typically known as Debug and Release variant. When no build type is configured for a native component, the plugin creates a default build configuration named Default. When a component does not build on the host machine due to missing toolchain, for example, the plugin creates a default build configuration named Unbuildable instead.

In a vanilla Xcode experience, developers would use the build settings to configure a particular aspect of a product’s build process. With the Xcode IDE plugin, developers configure the product’s build process using the Gradle build language. Modifying the build settings inside Xcode is discourage and is unlikely to have the desired effect.

You should now have a grasp on the concept used by Xcode IDE Plugin. Head over the IDE samples to see a demonstration of the plugins for common scenarios. Bookmark the relevant plugin chapters for future reference.

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