title: How to create a static NSRange?
body: <p>It is really a stupid question, but I really don't know how to. 
  I have a utility class and need to define some pre-defined variables. Here's how my class looks.</p>
  
  <pre><code>#pragma mark File header part definiation (start offset, length)
  NSRange HEADER_VERSION = NSMakeRange(0, 4); /* 0,4 */
  NSRange HEADER_IDENTIFIER = NSMakeRange(4, 18); /* 4, 18*/ 
  ...
  
  @interface ParserUtil : NSObject {
  
  }
  
  /*Parse Paper instance from file*/
  +(Paper*) parsePaper:(NSURL*)file;
  @end
  </code></pre>
  
  <p>The compiler tell me the second and the third lines are error:</p>
  
  <blockquote>
    <p>initializer is not constant.</p>
  </blockquote>
  
  <p>What is the best practice of defining the variables?</p>