What about when the user is offline ? All notifications are collapsed and only the last one is received. How can I receive all notifications and save them using the shared container ? What can I do to ensure that each notification gets delivered ? I am trying to replicate WhatsApp's effect where all messages are delivered using notifications where as soon as a notification is received, the message is locally saved and don't need any On-App-Start re-syncing with server. If there is another better way of achieving this effect, it would be much help.

This is true. I tried using Safari, Chrome, Firefox, on both mac mini, mac book and iphone but none worked. Even the "download attached file" trick on safari didn't work. Only using Tor browser worked. Thanks