title: Constants in Objective-C
body: <p>I'm developing a <a href="http://en.wikipedia.org/wiki/Cocoa_%28API%29" rel="noreferrer">Cocoa</a> application, and I'm using constant <code>NSString</code>s as ways to store key names for my preferences.</p>
  
  <p>I understand this is a good idea because it allows easy changing of keys if necessary.<br>
  Plus, it's the whole 'separate your data from your logic' notion.</p>
  
  <blockquote>
    <p>Anyway, is there a good way to make these constants defined once for the whole application?  </p>
  </blockquote>
  
  <p>I'm sure that there's an easy and intelligent way, but right now my classes just redefine the ones they use. </p>