title: iOS: get available locales in my project
body: <p>I created several .strings files for my app's localization. Each one is corresponding to a locale. Now I  want to get a list of all available locale in my app. Is there any function to help me do that??</p>
  
  <p>E.g. if my app just supports English, Chinese, French
  the function can return [en, zh, fr]</p>