example-2.php

<?PHP

class CampaignManager_API extends APIController {  
                                                                        
...                                                                                                                                                               
                                                                                                                                                                         
   public function getClients(){                                                                                                                                         
      return $this->success(array(                                                                                                                                       
         'ClientList' => array()                                                                                                                                         
      ));                                                                                                                                                                
   }                                                                                                                                                                     
}                                                                                                                                                                        

example.php

<?PHP

class APIController extends Controller {                                                                                                     
...

   public function success($data){                                                                                                                                       
      $response = new SS_HTTPResponse();                                                                                                                                 
      $response->addHeader('Content-Type', 'application/json');                                                                                                          
      $response->setBody(json_encode(array(                                                                                                                              
         'success' => true,                                                                                                                                              
         'response' => $data                                                                                                                                             
      )));                                                                                                                                                               
      return $response;                                                                                                                                                  
   }     
   
   ...
 }