J2objc Packager for Gradle

Gradle plugin and libraries for J2objc development


Basic Quickstart / Tutorials


Config J2objc Runtime

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Doppl Project

Stack Overflow j2objc  / j2objc-gradle

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Basic Quick Start

See other tutorials in menu under “Basic Quickstart / Tutorials”

We’ll be cloning and building a very basic Android project, which shares just a little bit of standard Java code.

The iOS Xcode project that consumes the generated code is ready to go, so all we’ll be doing is making sure the necessary tools are installed and running everything. Not counting download time, assuming no install issues, this whole thing should take 5-10 minutes.


Clone Repo

Clone the BasicAndroidSample

git clone https://github.com/j2objcgradle/BasicAndroidSample.git
cd BasicAndroidSample

Build and run iOS

We can walk through more details later, but to see the plugin function, we’ll run J2objc on the shared Java code, then open and run the project in Xcode.

./gradlew j2objcBuild

Assuming this the first run, the plugin will download a J2objc runtime. It will take some time. You should see download status updates output to terminal.

If everything comes out OK, the next step is to run Cocoapods. The gradle plugin generates a definition file which points at the generated code. Running Cocoapods will wire the generated code to the Xcode project.

cd ios
pod install

Navigate in Finder to the project directory, open the ‘ios’ folder, and double-click ‘ios.xcworkspace’.

Select a simulator to run, and click ‘Run’.

If everything is set up correctly, you should see the app launch.

Video Tutorial

Watch the setup process here

Quick Start Tutorial Video

Project Detail

Gradle Config

The plugin and available libraries are currently kept in a bintray maven repository. The repo is at ‘https://dl.bintray.com/doppllib/j2objc’. In general you’ll want to add the repo to both the buildscript and project repository collections. Also add ‘org.j2objcgradle:gradle:0.12.1’ to the buildscript dependencies.

buildscript {
    ext.kotlin_version = '1.1.51'
    repositories {
        maven { url 'https://dl.bintray.com/doppllib/j2objc' }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "org.j2objcgradle:gradle:0.12.2"

allprojects {
    repositories {
        maven { url 'https://dl.bintray.com/doppllib/j2objc' }

In the app folder’s build.gradle, apply the Gradle plugin

apply plugin: 'org.j2objcgradle.gradle'

At the bottom of the file, add J2objc specific configuration

j2objcConfig {
    translatedPathPrefix 'com.kgalligan.basicandroid.shared', 'SH'

    translatePattern {
        include '**/shared/**'

In the projects gradle.properties file add:


The J2objc Gradle plugin can operate in two basic contexts: a separate Java module, and inside an Android project module. Inside a Java module, generally all of the Java code is shared to Objective-C. In an Android module, the shared code needs to be identified in the plugin config.