title: Send push notification to iOS device via Firebase (FCM) using HTTP Request after app is killed
body: <p>I am having trouble sending push notifications via Firebase through HTTP Request to my iOS device after the app is killed. When the app is in the foreground or active in the background everything work as expected. But if I kill the app it won't work. I am able to send notifications to my app through the Firebase console if the app is killed, so I believe something must be wrong with the code I am using.</p>
  
  <p>This is my code for sending the push notification:</p>
  
  <pre><code>    private void SendPushNotification(string devicetoken, string header, string content, string pushdescription)
      {
          var textNotification = new
          {
              to = devicetoken,
              notification = new
              {
                  title = header,
                  text = content,
                  content_available = true,
                  sound = "enabled",
                  priority = "high",
                  id = pushdescription,
              },
              project_id = "rrp-mobile",
          };
  
          var senderId = "212579566459";
          var notificationJson = Newtonsoft.Json.JsonConvert.SerializeObject(textNotification);
          using (var client = new WebClient())
          {
              client.Encoding = Encoding.UTF8;
              client.Headers[HttpRequestHeader.ContentType] = "application/json";
              client.Headers[HttpRequestHeader.Authorization] = "key=AIfrSyAtgsWCMH4s_bOyj-Us4CrdsifHv-GqElg";
              client.Headers["Sender"] = $"id={senderId}";
              client.Headers[HttpRequestHeader.ContentType] = "application/json";
              client.UploadString("https://fcm.googleapis.com/fcm/send", "POST", notificationJson);
          }
      }
  </code></pre>
  
  <p>Am I forgetting something here? This works for sending push notifications to Android devices both in foreground, background and when app is killed, and like I said also to iOS devices in foreground and background.</p>
  
  <p>The only issue is sending push notifications to iOS devices when the app has been killed. Does anyone have any idea as to how I would solve this issue? </p>