Latest 0.5.1
License MIT
Platforms ios 8.0, osx 10.9, requires ARC
Dependencies ObjectiveSugar, IGDigest
Frameworks JavaScriptCore

JavaScriptCore OpalAdditions

Ruby for Objective-C, via Opal and JavaScriptCore.


Evaulate Ruby in JavaScriptCore JSContext

#import <JavaScriptCore/JavaScriptCore.h>
#import "JSContext+OpalAdditions.h"

JSValue* value = [context evaluateRuby:@"[1,2,3,4,5].inject{|total, i| total + i }"];
[value toNumber]; // => 15

How require works

Opal works by compile Ruby into JavaScript. When running on JavaScriptCore however,
you don’t always want to load everything into the context.

OpalAdditions modify Opal implementation of require. You may require a ruby file
on runtime.

// require with Ruby
[context evaluateRuby:@"require 'singleton'"];


// require with Objective-C
[context requireRubyWithFilename:@"singleton" error:nil];

OpalAdditions will search the filename from $LOAD_PATH, compile the file and load it.

Note: If you always use certain classes, you should precompile them with opal-sprockets
and bundle the JavaScript instead.

Add your custom gems to $LOAD_PATH

You can add more path to $LOAD_PATH to load your custom gems:

// Add load path
NSString* newPath = [[NSBundle bundleForClass:[self class]] pathForResource:@"gems" ofType:nil];
[context appendOpalLoadPathsWithPath:newPath];

// load addition gems
[context requireRubyWithFilename:@"my_awesome_gems" error:nil];

You might want to add your gem path as "Folder Reference" instead of regular "Group".


To install JavaScriptCoreOpalAdditions throught CocoaPods, add following lines to your Podfile:

pod "JavaScriptCoreOpalAdditions", '~> 0.3.0'


Install Pods for Objective-C libraries

  1. pod install

Download submodule for opal, and build necessary files:

  1. git submodule update –init
  2. bundle install
  3. bundle exec rake


  • JavaScriptCore (iOS 7.0+)
  • Ruby (to compile opal)

Latest podspec

    "name": "JavaScriptCoreOpalAdditions",
    "version": "0.5.1",
    "summary": "Use Ruby in your Objective-C apps.",
    "description": "Use Ruby in your Objective-C apps by Opal and JavaScriptCore.",
    "homepage": "",
    "license": {
        "type": "MIT",
        "file": "LICENSE.txt"
    "authors": {
        "Francis Chong": "[email protected]"
    "source": {
        "git": "",
        "tag": "0.5.1"
    "platforms": {
        "ios": "8.0",
        "osx": "10.9"
    "frameworks": "JavaScriptCore",
    "dependencies": {
        "ObjectiveSugar": [
            "~> 1.1.0"
        "IGDigest": [
            ">= 1.1.3"
    "source_files": "JavaScriptCoreOpalAdditions/Classes/**/*.{h,m}",
    "resources": "JavaScriptCoreOpalAdditions/Opal.bundle",
    "requires_arc": true

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