A Symfony Service to send iOS Push Notifications.

SendIOSPushNotification.php

<?php

namespace App\Service\PushNotification;

class SendIOSPushNotification {

    /**
     * Constructor
     *
     * @param string $iosPushNotificationsKey
     * @param string $iosPushNotificationsKeyId
     * @param string $iosTeamId
     * @param string $iosAppBundleId
     * @param string $iosApnUrl
     */
    public function __construct(
        string $iosPushNotificationsKey,
        string $iosPushNotificationsKeyId,
        string $iosTeamId,
        string $iosAppBundleId,
        string $iosApnUrl
    ) {
        $this->iosPushNotificationsKey = $iosPushNotificationsKey;
        $this->iosPushNotificationsKeyId = $iosPushNotificationsKeyId;
        $this->iosTeamId = $iosTeamId;
        $this->iosApnUrl = $iosApnUrl;
        $this->iosAppBundleId = $iosAppBundleId;
    }

    /**
     * Sends a push notification to an iOS device
     *
     * @param string $deviceToken
     * @param string $title
     * @param string $subtitle
     * @param string $body
     * @return void
     */
    public function __invoke(string $deviceToken, string $title, string $subtitle, string $body) {
        $payload = $this->getNotificationPayload($title, $subtitle, $body);
        $key = openssl_pkey_get_private('file://'.$this->iosPushNotificationsKey);
        $header = $this->base64([
            'alg' => 'ES256',
            'kid' => $this->iosPushNotificationsKeyId
        ]);
        $claims = $this->base64([
            'iss' => $this->iosTeamId,
            'iat' => time()
        ]);
      
        $signature = '';
        openssl_sign($header . '.' . $claims, $signature, $key, 'sha256');
        $jwt = $header . '.' . $claims . '.' . base64_encode($signature);
      
        $http2ch = curl_init();
        curl_setopt_array($http2ch, [
          CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_2_0,
          CURLOPT_URL => $this->getUrlForDeviceToken($deviceToken),
          CURLOPT_PORT => 443,
          CURLOPT_HTTPHEADER => [
            "apns-topic: {$this->iosAppBundleId}",
            "authorization: bearer $jwt"
          ],
          CURLOPT_POST => TRUE,
          CURLOPT_POSTFIELDS => $payload,
          CURLOPT_RETURNTRANSFER => TRUE,
          CURLOPT_TIMEOUT => 30,
          CURLOPT_HEADER => 1
        ]);
      
        $result = curl_exec($http2ch);

        if ($result === FALSE) {
          throw new \Exception("Send push notification failed: ".curl_error($http2ch));
        }

        $status = curl_getinfo($http2ch, CURLINFO_HTTP_CODE);
        if ($status !== 200) {
            throw new \Exception("Send push notification failed: ".$result);
        }
    }

    /**
     * Obtains a base64 representation of an array
     *
     * @param array $data
     * @return string
     */
    private function base64(array $data) : string {
      return rtrim(strtr(base64_encode(json_encode($data)), '+/', '-_'), '=');
    }

    /**
     * Gets the notification payload as array
     *
     * @param string $title
     * @param string $subtitle
     * @param string $body
     * @return string
     */
    private function getNotificationPayload(string $title, string $subtitle, string $body) : string {
        $notificationBody = [
            'aps' => [
                'alert' => [
                    'title' => $title,
                    'subtitle' => $subtitle,
                    'body' => $body
                ]
            ]
        ];
        return json_encode($notificationBody);
    }

    /**
     * Gets the full url for send a push notification for a device
     *
     * @param string $deviceToken
     * @return string
     */
    private function getUrlForDeviceToken(string $deviceToken) : string {
        return "{$this->iosApnUrl}/3/device/{$deviceToken}";
    }

}