Firebase Push Notification and IOS APNs Notification when app killed - ios

Question

I am using Google Firebase to send push notifications. For Android client, I only send data (not notification) and if notification required, I send it as local notification and it works fine. Data arrive whether the app is running or killed or in the background. In IOS, I configured APNs with Firebase but I have some trouble about background data and notification. The code below sends background data to IOS client by using APNs. "content_available" flag direct notification to APNs but as Firebase documentation mentioned, APNs are not guaranteed to be delivered. The link below explains it.
https://firebase.google.com/docs/cloud-messaging/http-server-ref
"On iOS, use this field to represent content-available in the APNs payload. When a notification or message is sent and this is set to true, an inactive client app is awoken, and the message is sent through APNs as a silent notification and not through the FCM connection server. Note that silent notifications in APNs are not guaranteed to be delivered, and can depend on factors such as the user turning on Low Power Mode, force quitting the app, etc. On Android, data messages wake the app by default. On Chrome, currently not supported."
If I add the codes at the comment lines, APNs sent always notification whether the app is in foreground, background or killed. Of course, I don't want push notification if the app is in the foreground. Furthermore, if the user doesn't click the notification (click the app icon), the code is not triggered. Is there any way to use APNs as Firebase on Android? In Android background data notification always sent to the client successfully whether the app is in the foreground, background or killed.
private static String apiKey = "AIzaSy............";
public static void sendNotification(JSONObject jsonData, String token) {
try {
JSONObject jsonGCM = new JSONObject();
jsonGCM.put("to", token);
jsonGCM.put("data", jsonData);
jsonGCM.put("content_available", true);
//jsonGCM.put("priority", "high");
/*JSONObject jsonNotification = new JSONObject();
jsonNotification.put("title", "Some Title");
jsonNotification.put("body", "Some body.");
jsonGCM.put("notification", jsonNotification);*/
URL url = new URL(
//"https://gcm-http.googleapis.com/gcm/send");
"https://fcm.googleapis.com/fcm/send");
HttpsURLConnection conn = (HttpsURLConnection) url
.openConnection();
conn.setDoOutput(true);
conn.setDoInput(true);
conn.setRequestProperty("Content-Type",
"application/json; charset=UTF-8");
conn.setRequestProperty("Accept", "application/json");
conn.setRequestMethod("POST");
conn.setRequestProperty("Authorization", "key="
+ apiKey);
OutputStream os = conn.getOutputStream();
os.write(jsonGCM.toString().getBytes("UTF-8"));
os.flush();
InputStream in = new BufferedInputStream(
conn.getInputStream());
System.out.println("Response code -->"
+ conn.getResponseCode());
os.close();
}
catch (Exception e) {
// TODO: handle exception
}
}