Update Subscriber - Example of the code (PHP)

try {
                // Set the REST API URL
                $restURL = "https://api.enginemailer.com/restapi/subscriber/emsubscriber/updateSubscribers";
                
                // Initiate the cURL Method with the REST API URL Specified Previously.
                $client = curl_init($restURL);
                
                // Custom Fields declarations
                $jsonCustomFields1->customfield_key = "customfield_key";
                $jsonCustomFields1->customfield_value = "customfield_value";
                
                $jsonCustomFields2->customfield_key = "customfield_key";
                $jsonCustomFields2->customfield_value = "customfield_value";

                // Create the JSON Object with the Email, Subcategories, and Custom Fields
                // Email
                $jsonObject->email = "Email To Update"; 
                // Add the ID of the Subcategories into an Array to assign this Subscribers into the Subcategories
                $jsonObject->subcategories = array(); 
                // Custom Fields
                $jsonObject->customfields = array($jsonCustomFields1, $jsonCustomFields2);
                
                // Encode the Json Object into a String
                $jsonEncoded = json_encode($jsonObject);
                
                // Add APIKey into the Headers to be passed in.
                $headers = array(
                                "APIKey : "
                );
                
                // Return the Transfer as String
                curl_setopt($client, CURLOPT_RETURNTRANSFER, true); 
                // Use POST Method
                curl_setopt($client, CURLOPT_POST, true); 
                // Add Headers for Request
                curl_setopt($client, CURLOPT_HTTPHEADER, $headers);
                // The Post Parameters that we will be Passing
                curl_setopt($client, CURLOPT_POSTFIELDS, $jsonEncoded); 
                // Calls the Rest API
                $curl_response = curl_exec($client);
                curl_close($client);
                
                var_dump($curl_response);
}
catch (Exception $e)
{
                echo 'Caught exception: ',  $e->getMessage(), "\n";
}