Check if UUID is in valid format

verify-uuid.php

<?php
/**
 * Check if a given string is a valid UUID
 * 
 * @param   string  $uuid   The string to check
 * @return  boolean
 */
function isValidUuid( $uuid ) {
    
    if (!is_string($uuid) || (preg_match('/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/', $uuid) !== 1)) {
        return false;
    }

    return true;
}