Ruby script to switch locale on Xcode 6.3 / IOS 8.3

gistfile1.rb

require 'plist'
require 'colorize'


class SimLocale
  LANG_HASH||={
      "en_US" => {"AppleLanguages" => "en", "AppleLocale" => "en_US"},
      "en_GB" => {"AppleLanguages" => "en", "AppleLocale" => "en_GB"},
      "fr_FR" => {"AppleLanguages" => "fr", "AppleLocale" => "fr_FR"},
      "th_TH" => {"AppleLanguages" => "th", "AppleLocale" => "th_TH"},
      "es_ES" => {"AppleLanguages" => "es", "AppleLocale" => "es_ES"},
      "tr_TR" => {"AppleLanguages" => "tr", "AppleLocale" => "tr_TR"}
  }

  def change_sim_locale(sim_os, sim_name, sim_locale)
    puts "change_sim_locale"
    puts  "#{sim_os}, #{sim_name}, #{sim_locale}"
    sim_path=""
    found=false

    #get home folder
    home_folder=`echo ~`.strip

    #navigate to core devices folder
    core_devices="#{home_folder}/Library/Developer/CoreSimulator/Devices"
    `cd #{core_devices}`
    puts "Simulator location #{core_devices}"
    #list all dirs
    all_sims=Dir["#{core_devices}/*"]

    puts all_sims
    all_sims.each do |each_sim|
      sim_info = Plist::parse_xml("#{each_sim}/device.plist")
      if sim_info["name"] == sim_name && sim_info["runtime"].match(sim_os)
        sim_path= core_devices+"/"+sim_info["UDID"]
        found=true
        break
      end
    end

    if !found
      puts "ERROR: No compatible simulator found".red
      fail "" 
    end

    #execute plist buddy command
    global_pref_path=sim_path+"/data/Library/Preferences/.GlobalPreferences.plist"
    puts global_pref_path
    `echo #{global_pref_path}`

    locale= sim_locale

    puts LANG_HASH["#{sim_locale}"]
    abort if LANG_HASH["#{sim_locale}"]==nil # if locale is not specifed stop tests

    puts "#{LANG_HASH["#{locale}"]["AppleLanguages"]}"
    puts "#{LANG_HASH["#{locale}"]["AppleLocale"]}"

    `/usr/libexec/PlistBuddy #{global_pref_path} -c "Add :AppleLanguages:0 string '#{LANG_HASH["#{locale}"]["AppleLanguages"]}'"`
    `/usr/libexec/PlistBuddy #{global_pref_path} -c "Set :AppleLocale '#{LANG_HASH["#{locale}"]["AppleLocale"]}'"`

  end
#change_sim_locale(ENV['SIM_OS'],ENV['SIM_NAME'],ENV['LOCALE'])

end

SimLocale.new.change_sim_locale "8-3","iPhone 6 Plus","th_TH"

Please how can i solve this issue, I cloned the gistfile1.rb and i cd t the folder and run ruby gistfile1.rb but i get the following error:

lummy:f3f47daebc8998ef233c seunare$ ruby gistfile1.rb
/usr/local/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in require': cannot load such file -- plist (LoadError) from /usr/local/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:inrequire'
from gistfile1.rb:1:in `

'

thanks! this helped me a lot!