title: Helper functions in Cocoa
body: <p>What is the standard way of incorporating helper/utility functions in Obj-C classes?</p>
  
  <p>I.e. General purpose functions which are used throughout the application and called by more than 1 class.</p>
  
  <p>Can an Obj-C method exist outside of a class, or does it need to be a C function for it to have this kind of behaviour?</p>