Retrieve the key value from a arrayObject

This is my array:

ArrayObject::__set_state(
    array( 'data' => 
        array ( 
            'key1' =&开发者_开发百科gt; '573779', 
            'key2' => 'REF12345', 
            'key3' => '2010-07-12', 
            'key4' => '0000-00-00', 
            'key5' => '2010-07-12', 
            'key6' => '21654',
            'key7' => '0', 
            'key8' => ArrayObject::__set_state(array( )),
            'key9' => ArrayObject::__set_state(array( )), 
            'key10' => array ( ), 
            'key11' => array ( ), 
        )
)

I'm interested in finding out out how to retrieve any of the values for a key using SPL. Any of the keys can have arrays within arrays so I'm unsure how to obtain a value. I thought I may be able to use ->offsetGet('') but this only retrieves from the top-most array.

ArrayObject implements ArrayAccess so you can simply access them with the regular Array Notation, e.g.

echo $arrayObject['key1'];

In addition, ArrayObjects are IteratorAggregates, so you can iterate over them with foreach and decorate them with any of the SPL iterators, including the RecursiveIteratorIterator