CakeRequest::parseAccept PHP Method

    public function parseAccept()
    {
        return $this->_parseAcceptWithQualifier($this->header('accept'));
    }

 /**
  * Determines which content-types the client prefers. If no parameters are given,
  * the single content-type that the client most likely prefers is returned. If $type is
  * an array, the first item in the array that the client accepts is returned.
  * Preference is determined primarily by the file extension parsed by the Router
  * if provided, and secondarily by the list of content-types provided in
  * HTTP_ACCEPT.
  *
  * @param string|array $type An optional array of 'friendly' content-type names, i.e.
  *   'html', 'xml', 'js', etc.
  * @return mixed If $type is null or not provided, the first content-type in the
  *    list, based on preference, is returned. If a single type is provided
  *    a boolean will be returned if that type is preferred.
  *    If an array of types are provided then the first preferred type is returned.
  *    If no type is provided the first preferred type is returned.
  * @see RequestHandlerComponent::setContent()
  */
 public function prefers($type = null)
 {
     $acceptRaw = $this->request->parseAccept();
     if (empty($acceptRaw)) {
         return $this->ext;
     }
     $accepts = $this->mapType(array_shift($acceptRaw));
     if (!$type) {
         if (empty($this->ext) && !empty($accepts)) {
             return $accepts[0];
         }
         return $this->ext;
     }
     $types = (array) $type;
     if (count($types) === 1) {
         if (!empty($this->ext)) {
             return in_array($this->ext, $types);
         }
         return in_array($types[0], $accepts);
     }
     $intersect = array_values(array_intersect($accepts, $types));
     if (empty($intersect)) {
         return false;
     }
     return $intersect[0];
 }