title: How to convert "SEL" and "id" to NSString?
body: <pre><code>id parent;
  SEL selector;
  
  // lot's of code...
  
  if ([parent respondsToSelector:selector]) {
  
  }
  else {
      // This doesn't work:
      NSString *errorMessage = [NSString stringWithFormat:@"%@ in class %@ doesn't exist!", selector, parent];
  }
  </code></pre>
  
  <p>How do I convert "SEL" and "id" to a String?</p>