Special Characters Encoding Issue (PHP)

Question

I'm having difficulty correctly displaying Special Characters in our PHP application. The Special Characters are being displayed as "?" in most cases. I believe this has to do with the cURL operation.

We store our content in a Content Management System which we return via cURL. When I return our content via CMS, the Special Characters change to �. When I use mb_convert_encoding on these keys, it displays the Special Character as "?". How can I correctly display Special Characters? Any help would be appreciated!

Content Management System:

• Zürich Airport

Result Output - using cURL (Before mb_convert_encoding):

• Z�rich Airport

Page Output (After mb_convert_encoding):

• Z?rich Airport

Code:

    $curl = curl_init();
    curl_setopt($curl,CURLOPT_HTTPHEADER,array(
        'Content-type:application/json'
    ));
    curl_setopt($curl,CURLOPT_POST,true);
    curl_setopt($curl,CURLOPT_POSTFIELDS,json_encode(array(
        'contentKeyName' => $prefix,
        'langCode' => $language,
        'rollSetiForExperiments' => false
    )));
    curl_setopt($curl,CURLOPT_RETURNTRANSFER,true);
    curl_setopt($curl,CURLOPT_TIMEOUT,10);
    curl_setopt($curl,CURLOPT_URL,$endpoint);

    $response = new stdClass();
    $response->response = curl_exec($curl);
    $response->headers = curl_getinfo($curl);
    $response->error_number = curl_errno($curl);
    $response->error_message = curl_error($curl);

    curl_close($curl);

    $result = $response->response; // If I echo $result, Special Characters are outputted as �

    $result = mb_convert_encoding($result,'utf-8'); // Changes � to ? 

Desired Output:

• Zürich Airport