Issue using RecursiveIteratorIterator in a controller

I am attempting to call php's RecursiveIteratorIterator through a function in my controller class and I get the debugger message, "Class 'App\Controllers\RecursiveIteratorIterator' not found." My controller operates fine without this, although I would like to have the option to use it. Here is my code. Why does it think I am trying to call a controller and how can I remedy the error? Thank you in advance for your consideration.

PHP Code:

$newDataIterator = new RecursiveIteratorIterator( 
   new RecursiveArrayIterator(json_decode($dataArray, TRUE)),
   RecursiveIteratorIterator::SELF_FIRST
);