JavaScriptCoreOpalAdditions 0.5.1

JavaScriptCoreOpalAdditions 0.5.1

LangLanguage Obj-CObjective C
License MIT
ReleasedLast Release Jan 2016

Maintained by Francis Chong.

Depends on:
ObjectiveSugar~> 1.1.0
IGDigest>= 1.1.3

  • By
  • Francis Chong

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)