title: Generate a UUID string with ARC enabled
body: <p>I need to generate a UUID string in some code with ARC enabled.</p>
  
  <p>After doing some research, this is what I came up with:</p>
  
  <pre><code>CFUUIDRef uuid = CFUUIDCreate(NULL);
  NSString *uuidStr = (__bridge_transfer NSString *)CFUUIDCreateString(NULL, uuid);
  CFRelease(uuid);
  </code></pre>
  
  <p>Am I correctly using <code>__bridge_transfer</code> to avoid leaking any objects under ARC?</p>