My original article – “New in iOS 12: Adding a Custom UI and Interactivity in Local and Push Notifications” – was published on appcoda.com.
INTRODUCTION
If you look at Apple’s “What’s New in iOS” 12 page, you’ll find a section entitled “Interactive Controls in Notifications,” which exclaims:
Notification content app extensions now support user interactivity in custom views. If the content of your app’s notifications needs to prompt user interaction, add controls like buttons and switches.
In this tutorial, I’m going to show you how to give your local and remote (push) notifications a custom user interface (UI). Users can now interact with a notification’s content area. iOS 12 has given us the ability to add a UIViewController subclass to notifications which we can customize. We can add controls like UIButton, UIImageView, and UISwitch to the view controller, wire up custom functionality using IBOutlet and IBAction, and arrange our custom UI using Auto Layout — all within the notification itself. We can provide support for more than a single tap. We can develop pretty much any type of user experience we want, within notification space limitations and timing considerations.
I’ll show you how a user can take action in response to a notification by interacting only with a customized notification interface, and conveniently not having to open up an app. I’ll be showcasing software released to developers just ten days ago (June 19), specifically iOS 12 beta 2 and Xcode 10 beta 2.
By the end of this tutorial, you’ll be able allow to your app users to get a notification, see a custom UI, click on a button, and get a confirmation — all inside a notification, like so:
We’re going to learn about a feature of Swift called 
