Extract pattern from xml file using PHP?

I have a remote XML file. I need to read, find some values an save them in an array.

I've got load the file with (no problem with this):

$xml_external_path = 'http://example.com/my-file.xml';
$xml = file_get_contents($xml_external_path);

In this file there are many instances of:

<unico>4241</unico>
<unico>234</unico>
<unico>534534</unico>
<unico>2345334</unico>

I need to extract just the number of these strings and save them in a array. I guess I need to use a pattern like:

$pattern = '/<unico>(.*?)<\/unico>/';

But I'm not sure what to do next. Keep in mind that it is an .xml file.

Result should be a populated array like this:

$my_array = array (4241, 234, 534534,2345334);

You could try this, it basically just loops through each line of the file and finds whatever is between the XML <unico> tags.

<?php

$file = "./your.xml";
$pattern = '/<unico>(.*?)<\/unico>/';
$allVars = array();

$currentFile = fopen($file, "r");
if ($currentFile) {
    // Read through file
    while (!feof($currentFile)) {
        $m_sLine = fgets($currentFile);
        // Check for sitename validity
        if (preg_match($pattern, $m_sLine) == true) {
            $curVar = explode("<unico>", $m_sLine);
            $curVar = explode("</unico>", $curVar[1]);
            $allVars[] = $curVar[0];
        }
    }
}
fclose($currentFile);
print_r($allVars);

Is this sort of what you want? :)