A new feature for notifications in iOS 12 is the possibility to group notifications. iOS will group notifications from an application together by default, showing the user a stack of notifications with the most recent one on top, instead of a long list of mixed notifications from all applications, which is hard to scan through.
In this section, you will learn exactly how you can implement grouped notifications in your own apps.
Grouped notifications are a huge improvement for the notification system on iOS, which many users have eagerly been waiting for. However, if all notifications for a single app are grouped together, important information might get lost. If a messaging app stacks all notifications in a single group, it's easy to miss an important message if it's hidden somewhere in the group.
For this reason, Apple allows developers to create custom notification groups based on special thread identifiers...