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Alex Rupérez

Published: 21 Dec 12:20
I starred touchlab/xcode-kotlin at GitHub.
Kotlin Native Xcode Plugin
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Kotlin Native Xcode Support

Plugin to facilitate debugging iOS applications using Kotlin Native in Xcode. Defines Kotlin files as source code, with basic highlighting. Allows you to set breakpoints and includes llvm support to view data in the debug window.

We're Hiring!

Touchlab is looking for Android-focused mobile engineers, experienced with Kotlin and looking to get involved with Kotlin Multiplatorm in the near future. More info here.

Xcode 11+

Xcode does not officially support custom language definitions, but they also don't explicitly block them. However, Xcode 11 introduced several breaking changes from earlier versions, and some resolutions are still outstanding.

Xcode <= 10.x

For earlier versions, please see xcode10 branch. Life moves on, and we'll only be supporting Xcode 11+.


There are 2 parts to Kotlin support: 1) debugging support and 2) language color and style formatting.

Step 1: Debugging Support

You need to tell Xcode that *.kt files are source files, and run an lldb formatter script when debugging starts. Advanced users may want to do this manually, but if you have Xcode installed in the default place, you can run the setup script.


Step 2: Formatting Support

In Xcode 11, you need to move some files into a protected area. Some users may not want to do this, and may possibly not have permissions to do this. You'll need to run the script with sufficient permissions, which generally means sudo.

You can still debug Kotlin without formatting support, just FYI. This step is not required.

sudo ./

Kotlin 1.3.6x Issue

Using static frameworks and/or Cocoapods may remove debug info in this version. More info here

Special Note

All of that magic was sorted out by Ellen Shapiro, who undrestands all of this far better than I ever will.

Tracking Issue Here


If properly set up, you should be able to add Kotlin source to Xcode, set up breakpoints, and step through code.

We're deprecating the Xcode Sync plugin. Add folder reference instead! See issue. Description and video coming soon.

To help automate adding Kotlin source, check out the Kotlin Xcode Sync Gradle plugin.


The Droidcon NYC app has both the Xcode Gradle sync and Xcode projects enabled for debugging.


Setting up the Plugin has been an amalgam of various source projects, as Xcode "Plugins" are undocumented. The most significant piece, the language color file, came from other color files shipped with Xcode. Xcode plugin file from GraphQL

LLDB formatting originally comes from the Kotlin/Native project, source, although the way data is grabbed has been heavily modified to better support an interactive debugger.

Possible Future Stuff

Color File

The color definition is basically Java's with minor additions. This could be better adapted to Kotlin.


It's a bash script, which works, but does not take into account non-standard install directories and various other possible config options. This could be improved.

From Swift

You can see variables when you're debugging Kotlin, but when you're in a swift file that has a class that came from Kotlin you can't see much. It would be great to be able to improve that.

Better Debug Alignment

This happens in the Kotlin compiler, so it's a little deeper, but the breakpoints don't always track with the source when there are more complex structures (lambdas, etc). This should improve over time.

Xcode Updates

Every time Xcode is updated we need the UUID. It needs to be added to Kotlin.ideplugin/Contents/Info.plist. To find the UUID of your version of Xcode, run the following:

defaults read /Applications/ DVTPlugInCompatibilityUUID

Info from here