title: Casting an NSObject to NSString
body: <p>I am working through the <a href="http://www.stanford.edu/class/cs193p/cgi-bin/index.php" rel="noreferrer">Stanford iPhone class</a> and I can't figure out why I am getting a compiler warning. I assume I need to cast my object to NSString, but I get an error when I try to do so. The code runs and gives me the expected output, but the warning bothers me.</p>
  
  <pre><code>NSLog(@"lowerCaseString is: %@", [object lowercaseString]);
  </code></pre>
  
  <p>This runs with the warning: 'NSObject' may not respond to '-lowerCaseString'</p>
  
  <pre><code>NSLog(@"lowerCaseString is: %@", [(NSString)object lowercaseString]);
  </code></pre>
  
  <p>This throws an error: conversion to non-scalar type requested</p>