Ruby FFI bindings for the OSX Cocoa API
gem install cocoa
require 'cocoa'
Cocoa::NSAutoreleasePool.new
app = Cocoa::NSApplication.sharedApplication
app.setActivationPolicy Cocoa::NSApplicationActivationPolicyRegular
app.activateIgnoringOtherApps true
alert = Cocoa::NSAlert.alloc.init.autorelease
alert.setMessageText "Hello world!"
alert.runModal