Gradle Plugin for J2ObjC, which is an open-source tool from Google that translates Java source code to Objective-C for the iOS (iPhone/iPad) platform. The plugin is not affiliated with Google but was developed by former Google Engineers and others. J2ObjC enables Java source to be part of an iOS application's build, no editing of the generated files is necessary. The goal is to write an app's non-UI code (such as application logic and data models) in Java, which is then shared by Android apps (natively Java), web apps (using GWT), and iOS apps (using J2ObjC).
At HEAD, this plugin is in a state of flux as we refactor it into a first-class Gradle plugin for our beta. You may wish to wait for the beta release as we may make backwards incompatible changes before that point.
You should start with a clean java only project without any android dependencies.
It is suggested that the project is named shared. It must be buildable using the standard
Gradle Java plugin.
Starting as an empty project allows you to gradually shift over code from an existing
Android application. This is beneficial for separation between the application model
and user interface. It also allows the shared project to be easily used server side as well.
The Android app, shared Java project and Xcode should be sibling directories, i.e children
of the same root level folder. Suggested folder names are 'android', 'shared' and 'ios'
respectively. See the section below on Folder Structure.
Configure shared/build.gradle in your Java only project:
// File: shared/build.gradle
plugins {
id 'java'
id 'com.github.j2objccontrib.j2objcgradle' version '0.4.2-alpha'
}
// Plugin settings:
j2objcConfig {
xcodeProjectDir '../ios' // Xcode workspace directory (suggested directory name)
xcodeTarget 'IOS-APP' // iOS app target name (replace with existing app name)
finalConfigure() // Must be last call to configuration
}Info on additional j2objcConfig settings are in J2objcConfig.groovy.
Within the Android application's android/build.gradle, make it dependent on the shared project:
// File: android/build.gradle
dependencies {
compile project(':shared')
}Gradle 2.4 is required for the compilation support within Gradle. The other necessities are the J2objc Requirements.
* Gradle 2.4
* JDK 1.7 or higher
* Mac workstation or laptop
* Mac OS X 10.9 or higher
* Xcode 6 or higher
Download the latest version from the J2ObjC Releases. Find (or add) the local.properties in your root folder and add the path to the unzipped folder:
# File: local.properties
j2objc.home=/J2OBJC_HOMEThe plugin will output the generated source and libaries to the build/j2objcOutputs
directory and run all tests. It is integrated with Gradle's Java build plugin and may
be run as follows:
./gradlew shared:build
During development, to build the libraries and update Xcode (skipping the tests):
./gradlew shared:j2objcXcode
For a complete build, run both:
./gradlew shared:build shared:j2objcXcode
When using the j2objcTask, open the .xcworkspace file in Xcode. If the .xcodeproj file
is opened in Xcode then CocoaPods will fail. This will appear as an Xcode build time error:
library not found for -lPods-IOS-APP-j2objc-shared
Also see the FAQ note on developing with Swift.
You can reduce the build time by 50% by skipping the release binaries by adding the
following to your root level local.properties file:
j2objc.release.enabled=falseThis is helpful for a tight modify-compile-test loop using only debug binaries.
You can also do this for j2objc.debug.enabled.
If you'd rather just disable release builds for a particular run of the command line:
J2OBJC_RELEASE_ENABLED=false ./gradlew buildThe local.properties value overrides the environment variable, if present.
A number of standard libraries are included with the J2ObjC releases and linked by default when using the plugin. To add other libraries, see the FAQ dependency on a Java project. The standard libraries are:
guava
javax_inject
jsr305
junit
mockito
protobuf_runtime - TODO: https://github.com/j2objc-contrib/j2objc-gradle/issues/327
This is the suggested folder structure. It also shows a number of generated files and folders that aren't committed to your repository (marked with .gitignore). Files are shown before folders, so it is not in strict alphabetical order.
workspace
├── .gitignore // Add Ignores: local.properties, build/, Pod/
├── build.gradle
├── local.properties // sdk.dir=<Android SDK> and j2objc.home=<J2ObjC>, .gitignore
├── settings.gradle // include ':android', ':shared'
├── android
│ ├── build.gradle // dependencies { compile project(':shared') }
│ └── src/... // src/main/java/... and more, only Android specific code
├── ios
│ ├── IOS-APP.xcworkspace // Xcode workspace
│ ├── IOS-APP.xcodeproj // Xcode project, which is modified by j2objcXcode / CocoaPods
│ ├── Podfile // j2objcXcode modifies this file for use by CocoaPods, committed
│ ├── IOS-APP/... // j2objcXcode configures dependency on j2objcOutputs/{libs|src}
│ ├── IOS-APPTests/... // j2objcXcode configures as above but with "debug" buildType
│ └── Pods/... // generated by CocoaPods for Xcode, .gitignore
└── shared
├── build.gradle // apply 'java' then 'j2objc' plugins
├── build // generated build directory, .gitignore
│ ├── ... // other build output
│ ├── binaries/... // Contains test binary: testJ2objcExecutable/debug/testJ2objc
│ ├── j2objc-shared.podspec // j2objcXcode generates these settings to modify Xcode
│ └── j2objcOutputs/... // j2objcAssemble copies libraries and headers here
├── lib // library dependencies, must have source code for translation
│ ├── lib-with-src.jar // library with source can be translated, see FAQ on how to use
│ └── libpreBuilt.a // library prebuilt for ios, see FAQ on how to use
└── src/... // src/main/java/... shared code for translation
These are the main tasks for the plugin:
j2objcCycleFinder - Find memory cycles that can cause leaks, see FAQ for more details
j2objcTranslate - Translates Java source to Objective-C
j2objcAssemble - Outputs packed libraries, source & resources to build/j2objcOutputs
j2objcTest - Runs all JUnit tests in the translated code
j2objcBuild - Runs j2objcAssemble and j2objcTest, doesn't run j2objcXcode
j2objcXcode - Xcode updated with libraries, headers & resources (uses CocoaPods)
Running the build task from the Gradle Java plugin will automatically run the j2objcBuild command
and all the previous tasks (which it depends on). Only the j2objcXcode task needs to be manually
run. Note that you can use the Gradle shorthand of $ gradlew jA to do the j2objcAssemble task.
The other shorthand expressions are jCF, jTr, jA, jTe, jB and jX.
See FAQ.md.
See CONTRIBUTING.md.
This library is distributed under the Apache 2.0 license found in the LICENSE file.