title: "sending 'const NSString *' to parameter of type 'NSString *' discards qualifiers" warning
body: <p>I have Constants NSString, that I want to call like:</p>
  
  <pre><code>[newString isEqualToString:CONSTANT_STRING];
  </code></pre>
  
  <p>Any wrong code here?</p>
  
  <p>I got this warning:</p>
  
  <blockquote>
    <p>sending 'const NSString *' to parameter of type 'NSString *' discards qualifiers</p>
  </blockquote>
  
  <p>How should these be declared?</p>