src/Protocol/HttpProtocol.php
private function doSend(Receiver $receiver, Notification $notification, bool $sandbox): void
    {
        $payloadEncoded = $this->payloadEncoder->encode($notification->getPayload());
        $uri = $this->uriFactory->create($receiver->getToken(), $sandbox);

        $request = new Request($uri, $payloadEncoded);

        $headers = [
            'content-type' => 'application/json',
            'accept'       => 'application/json',
            'apns-topic'   => $receiver->getTopic(),
        ];

        $request = $request->withHeaders($headers);
        $request = $this->authenticator->authenticate($request);

        $request = $this->visitor->visit($notification, $request);

        $response = $this->httpSender->send($request);

        if ($response->getStatusCode() !== 200) {
            throw $this->exceptionFactory->create($response);
        }
    }
private function doSend(Receiver $receiver, Notification $notification, bool $sandbox): void
    {
        $payloadEncoded = $this->payloadEncoder->encode($notification->getPayload());
        $uri = $this->uriFactory->create($receiver->getToken(), $sandbox);

        $request = new Request($uri, $payloadEncoded);

        $headers = [
            'content-type' => 'application/json',
            'accept'       => 'application/json',
            'apns-topic'   => $receiver->getTopic(),
        ];

        $request = $request->withHeaders($headers);
        $request = $this->authenticator->authenticate($request);

        $request = $this->visitor->visit($notification, $request);

        $response = $this->httpSender->send($request);

        if ($response->getStatusCode() !== 200) {
            throw $this->exceptionFactory->create($response);
        }
    }
Inner send process

@param Receiver     $receiver
@param Notification $notification
@param bool         $sandbox

@throws SendNotificationException
@throws HttpSenderException