PHP Post data to API page

I have this PHP class for an API:

class Integra {
    public function __construct()
    {
        $this->api_key = 'API-XXXXXXX';
        $this->api_salt = '';
    }

    public function build_query($type, $data = array())
    {
        //$salted = hash_hmac('md5', $this->api_key, $this->api_salt);

        //$data['api_key'] = $salted;
        //$data['key'] = $this->api_key;
        $params = $data;

        $data_string = json_encode($params);  

        $ch = curl_init('http://domain.com/api.php');                                                               
        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");                                                                     
        curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);                                                                  
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
        curl_setopt($ch, CURLOPT_HTTPHEADER, array(                                                                          
        'Content-Type: application/json')
        );

        $response = curl_exec($ch);
        curl_close($ch);

        $response = json_decode($response);

        return $response;
    }
}

so this is posting data to the relevant page/function.

I want to be able to return the data as objects, i have tried the following on the page that the data is being posted to but nothing is being returned.

What have i done wrong?

<?php
return array('status' => 'test', 'reason' => 'test2');
?>

Here is how i call the class and function:

$Integra = new Integra();
$output = $Integra->build_query('check_system.php');

echo $output->reason;
echo $output->status;