CodeIgniter在IFTTT上返回未知响应

Question

I am testing the CodeIgniter 3.1 code by making a simple web service.

I found some issue with the response of the API on IFTTT.

The code I have used for the API response in the CI Controller is as below

public function setup()
{
        $method = $_SERVER['REQUEST_METHOD'];
        $header = $this->input->request_headers();
        $IFTTT_Channel_Key = $header["Ifttt-Channel-Key"];
        $IFTTT_Service_Key = $header["Ifttt-Service-Key"];
        if(
              ("xyz" === trim($IFTTT_Channel_Key) ) && 
              ("xyz" === $IFTTT_Service_Key)){                  

              $data = array(
                    "data" => array(
                          "accessToken" => "1224124112411",
                          "samples" => array(
                                "actions" => array(
                                      "turn_on_light" => array(
                                            "device_name" => "my_device"
                                      )
                                )
                          )
                    )
              );
              $ci =& get_instance();
              $this->output->set_status_header(200);
              $ci->output->set_content_type('application/json');
              $ci->output->set_output(json_encode($data));              
              echo json_encode($data);
        }
}

The response in the IFTTT Platform :

���{"data":{"accessToken":"1224124112411","samples":{"actions":{"turn_on_light":{"device_name":"my_device"}}}}}

The Response in the Postman tool :

{"data":{"accessToken":"1224124112411","samples":{"actions":{"turn_on_light":{"device_name":"my_device"}}}}}

Note: Please don't edit the question without understanding the actual issue. Please