Parse XML with PHP and get nested level element value and attribute value

$xml = new SimpleXMLElement($string); //variable $string is nothing but your XML content
$result = $xml->xpath('/propertyList/business/listingAgent/telephone');
//short form
//$result = $xml->xpath('////telephone');
foreach($result as $node) {
  print 'Telephone Atrribute: '.$node->attributes().'<br>';
}

The problem you have is in this line:

$commercialListingType = (array)$business['commercialListingType'];

As $commercialListingType is a SimpleXMLElement you don't need to cast it to an array - it allows to access anything you need already via it's standard object and array-access notations. Casting to an array will reduce the functionality with the risk to break it.

And that is what is exactly happening here in your case on the next line:

print_r($commercialListingType->attributes());

Give you the famous

Fatal error: Call to a member function attributes() on a non-object

error, as you told PHP to make $commercialListingType an array - which is not an object in PHP.

So better understand that with SimpleXMLElement, there is no need to cast to array:

$data = array();

foreach ($xml->business as $business)
{
    $uniqueID = (string)$business->uniqueID;

    if (isset($data[$uniqueID])) {
        continue;
    }

    $listingAgent          = $business->listingAgent;
    $price                 = $business->price;
    $commercialListingType = $business->commercialListingType;

    $data[$uniqueID] = array(
        'agentID'   => (string) $business->agentID,
        'uniqueID'  => $uniqueID,
        'name'      => (string)$listingAgent->name,
        'email'     => (string)$listingAgent->email,
        'price'     => (string)$price,
        'telephone' => (string)$listingAgent->telephone,
        'mobile'    => (string)$listingAgent->telephone[1],
    );
}

You find more usage examples in the PHP manual: http://www.php.net//manual/en/simplexml.examples-basic.php

This will also explain to you how to access attributes.

So remember: It is a fault casting to array with SimpleXML. Whoever told you to do that and said to you it would make things more easy, was not telling you the whole story.

Exemplary output:

Array
(
    [1420648] => Array
        (
            [agentID] => TEST
            [uniqueID] => 1420648
            [name] => hjon Smith
            [email] => [email protected]
            [price] => 200000
            [telephone] => 
            [mobile] => 
        )

)

Demo online: https://eval.in/159675 ; Full Code:

<?php 
/**
 * @link http://stackoverflow.com/a/24096869/367456
 */ 
ob_start(); 
?>
    <propertyList date="2014-06-02-17:30:33" username="bad" password="dfdfd">
        <business modTime="2014-06-02-12:22:32" status="current">
            <agentID>TEST</agentID>
            <uniqueID>1420648</uniqueID>
            <listingAgent id="1">
                <name>hjon Smith</name>
                <telephone type="BH"></telephone>
                <telephone type="mobile"></telephone>
                <email>[email protected]</email>
            </listingAgent>
            <listingAgent id="2"></listingAgent>
            <address display="no">
                <subNumber>Yoghurt bbd 4000</subNumber>
                <streetNumber></streetNumber>
                <street></street>
                <suburb display="no">Newy</suburb>
                <state>NSW</state>
                <postcode>2000</postcode>
                <country>London</country>
            </address>
            <price display="yes" plusSAV="no" tax="exclusive">200000</price>
            <priceView></priceView>
            <externalLink href=""/>
            <externalLink href=""/>
            <videoLink href=""/>
            <underOffer value="no"/>
            <commercialListingType value="sale"/>
            <franchise value="yes"/>
            <businessCategory id="1">
                <name>Franchise</name>
            </businessCategory>
        </business>
    </propertyList>
<?php
/**
 */
$xml = simplexml_load_string(ob_get_clean());

$data = array();

foreach ($xml->business as $business)
{
    $uniqueID = (string)$business->uniqueID;

    if (isset($data[$uniqueID])) {
        continue;
    }

    $listingAgent          = $business->listingAgent;
    $price                 = $business->price;
    $commercialListingType = $business->commercialListingType;

    $data[$uniqueID] = array(
        'agentID'   => (string) $business->agentID,
        'uniqueID'  => $uniqueID,
        'name'      => (string)$listingAgent->name,
        'email'     => (string)$listingAgent->email,
        'price'     => (string)$price,
        'telephone' => (string)$listingAgent->telephone,
        'mobile'    => (string)$listingAgent->telephone[1],
    );
}

print_r($data);