How to know Push Notification delivery status

Question

I am using push notification in an app. Everything is going fine.

Sometimes message sent from server but in app side it does not receive.

In this situation I have to know which message is missing to deliver(app did not receive).

Is there any way to know from server side which message is received by app and which are not?

Answer 1

Nopes, push notifications are fire-and-forget.

Apple will not tell you the following:

1. Will not tell whether the message was sent successfully or not
2. Will not tell if the user has opted out of Push Notifications
3. Many other things but anyways...

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However

On the other hand, when the user has opted for Push Notifications then your app can handle this but to a certain extent:

Basically, you could add logic in the -didReceiveRemoteNotification: and -didFinishLaunchingWithOptions: to contact your server and tell your server that the message was received.
If it wasn't received within a particular time slot then you can resend it.

But as you see, this could lead to a possible scenario of flooding an innocent user with the same push notifications.
In a sense, harassing him to tap your stupid push notification, which in turn may lead him to switch off push notifications for your app entirely but mostly he would delete the app and maybe even give it a low rating?
Serves you right, I'll say.

Anyways, if you go ahead with this, you would need to implement an identification pattern where you insert a unique message identifier into the payload of the push notification and when your app gets this push notification, it should send this message identifier back to the server.
Your server should then log that a particular device token returned a message identifier, which means it received that particular push notification.

Your server can check on a hourly/daily/whateverly basis and resend a particular message to those device tokens that have not reported back with the relative message identifier.

Again, this means your server might need to work OT sometimes.

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There are other issues with this whole approach:

1. User received push notification but dismisses it rather than opening your app with it
   • Your server will assume the user did not see the push notification and will send this push notification again
2. Ghost device tokens
   • User accepted push notifications at first but later revoked this privilege
   • User uninstalled the app
   • Basically, device tokens that once use to receive push notification but no longer do, most probably due to your message flooding reputation
3. User received push notification but taps it at a later time
   • might get same push notification multiple times (very irritating)
4. User received push notification but taps it when there is no internet connectivity
5. User received push notification but your server is down, possibly fried \m/

You can circumvent the last 3 scenarios by having even more logic in your app that queues the message id's that are to be sent to the server and removes it only when the server responds successfully.

So you see, too much work, server-side + client-side.
Plus it's a massive performance degrader on the server-side when dealing with a good volume of users as well as lowering the performance of your app by a wee bit.