Keep in mind that "quick reply" as implemented by Apple apps like Messages (e.g., where you can reply using an inline text field without even switching to the app) is not available to third-party developers. Third-parties are limited to two buttons and a default action when the notification is tapped (unless it's an alert-style notification that appears in the foreground, in which case they can have more buttons.)
There is no support in the public notification actions API for the inline text field, unfortunately. It's quite a shame, as I think this was perhaps the most useful part...
In other words, you can do things like "archive", "snooze", "dismiss", "accept", etc. You could even have a button that sent a default message like "be right there!" You cannot, however, have an arbitrary user-created text string sent to your app from the notification.