title: what the difference between NSBundle and CFbundle?
body: <pre><code> NSBundle* mainBundle = [NSBundle mainBundle];
  </code></pre>
  
  <p>I know we can use the above to get the mainBundle</p>
  
  <p>But I saw someone use </p>
  
  <pre><code>CFBundleRef mainBundle = CFBundleGetMainBundle();
  </code></pre>
  
  <p>Is there any difference between those two?</p>