SPM Local Dev Flow

After you have integrated your Kotlin module into Xcode using SPM, you may want to locally build and test your Kotlin code when making changes.

SPM is not integrated out of the box with Kotlin, and SPM itself does not allow external build tools to be used. The SPM local dev support provided by KMMBridge is functional, but requires manual CLI steps to function.

Since KMMBridge is generating your Package.swift files, the first step is to run a dev build step to build the local dev Package.swift and locally build a debug version of the Kotlin code.

./gradlew spmDevBuild

This should:

• Build a debug version of the XCFramework
• Write a local dev path to Package.swift

Next, you need to manually copy the whole Kotlin project into Xcode. That means, quite literally, drag the Kotlin project’s folder into Xcode.

In the sample above, the package allshared is inside KevsKmmTest. When you drag it in, if Xcode properly recognizes it, you’ll see allshared disappear, but when you build, things should work as expected.

Xcode is picky about the setup here. If the folder name of the local folder you drag in differs from the name of the git repo that you have for the library, Xcode won’t use it. It attempts to make sure you are using the right project, but it can fail to validate, which is pretty confusing. If you get errors trying to use a local build, be aware that Xcode can fail for non-obvious reasons.

When you run spmDevBuild, it will build all architectures, which you probably don’t need for testing on a simulator. To restrict architectures when building, you can pass in a Gradle param.

./gradlew spmDevBuild -PspmBuildTargets=ios_simulator_arm64

ios_simulator_arm64 is for mac Arm machines (M1, M2, etc). For Intel Macs, use ios_x64.

When you are done making and testing local changes, select the folder you dragged in, and remove it by right-clicking it and selecting “Delete”. Make sure to select “Remove References” on the popup. Xcode should then reload the remote version you had previously.

If you find the process of dragging and deleting strange, you are not alone. If you happend to figure out a better process, please reach out :)