public function getUnregisteredDeviceTokens(array $devices_token)
    {
        /**
         * If there is any failure sending the notification
         */
        if ($this->feedback && isset($this->feedback->failure)) {
            $unRegisteredTokens = $devices_token;

            /**
             * Walk the array looking for any error.
             * If no error, unset it from all token list which will become the unregistered tokens array.
             */
            foreach ($this->feedback->results as $key => $message) {
                if (!isset($message->error)) {
                    unset($unRegisteredTokens[$key]);
                }
            }

            return $unRegisteredTokens;
        }

        return [];
    }
public function getUnregisteredDeviceTokens(array $devices_token)
    {
        /**
         * If there is any failure sending the notification
         */
        if ($this->feedback && isset($this->feedback->failure)) {
            $unRegisteredTokens = $devices_token;

            /**
             * Walk the array looking for any error.
             * If no error, unset it from all token list which will become the unregistered tokens array.
             */
            foreach ($this->feedback->results as $key => $message) {
                if (!isset($message->error)) {
                    unset($unRegisteredTokens[$key]);
                }
            }

            return $unRegisteredTokens;
        }

        return [];
    }
public function getUnregisteredDeviceTokens ( array $ devices_token ) { /**
         * If there is any failure sending the notification
         */ if ( $ this -> feedback && isset ( $ this -> feedback -> failure ) ) { $ unRegisteredTokens = $ devices_token ; /**
             * Walk the array looking for any error.
             * If no error, unset it from all token list which will become the unregistered tokens array.
             */ foreach ( $ this -> feedback -> results as $ key => $ message ) { if ( ! isset ( $ message -> error ) ) { unset ( $ unRegisteredTokens [ $ key ] ) ; } } return $ unRegisteredTokens ; } return [ ] ; }
Provide the unregistered tokens of the sent notification.

@param array $devices_token
@return array $tokenUnRegistered
Provide the unregistered tokens of the sent notification .