utf 8 - php Cannot modify header information

I'm trying to return a json that has been ut8_encoded. I'm
setting before it, the header to HTTP response code
also.

 /**
 * Set the response
            header and HTTP response code and response the data
 * @param $data array of
            response to be encoded as json
 * @param int $status the http status (200 is
            default)
 * @return string the json presentation of the array given

            */
 public function response($data, $status = 200)
 {

            header("HTTP/1.1 " . $status . " " . $this->getRequestStatus($status));

            echo utf8_encode(json_encode($data, JSON_UNESCAPED_SLASHES));

            }

The results are coming back ok
but with a warning -

Warning: Cannot modify header information - headers already sent by (output
started at RestApi.php:115) in RestApi.php on line
113

edit:
Sorry,
I probably should of add it - The warning is talking about those two lines that causing
the warning.

How can I remove the
warning?

The error can occur if I'm adding this part to the
.htaccess ?

            mod_headers.c>
 Header set Access-Control-Allow-Origin "*"

            Header set Access-Control-Allow-Methods "*"
 Header set Content-Type
            "application/json;
            charset=utf-8"

I
just realized. So maybe I don't really need to encode the
response