title: Valid file path for archiverootobject and unarchiverootobject
body: <p>I am making an iPhone app and in a <a href="https://stackoverflow.com/questions/34627674/retrieve-array-function-not-working">previous question</a> I was told that I needed a valid file path for archiverootobject and unarchiverootobject but I don't know how to make one. So what is a valid file path to save arrays of custom classes?</p>
  
  <p>Follow up question: On the linked question I have set up my methods to use invalid  saves but it still works would anyone know why?</p>