example.php

<?php

class Collection implements \IteratorAggregate
{
    private $foo;
    private $bar;
    private $collection;

    public function __construct(\Traversable $collection)
    {
        $this->foo = 'bar';
        $this->bar = 'foo';
        $this->collection = $collection;
    }

    public function getIterator()
    {
        return new \ArrayIterator($this->collection);
    }
}

$collection = new Collection(new \ArrayObject([
    new \stdClass(), new \stdClass(), new stdClass()
]));

var_dump(next($collection));die();;

// "foo"