Mastering WidgetKit in SwiftUI 4, iOS 16 with Dynamic Island - Reminder App Constants

The video tutorial guides viewers through creating a constants file in Swift for a widget and app, ensuring shared use of static variables like storage keys and app group names. It emphasizes selecting the correct target membership and copying exact names to avoid errors. The tutorial concludes by preparing viewers for the next video, where they will create a reminder widget.

Explain the relationship between the app group name and the widget.

What are the key functionalities that the app constants file provides for both the app and the widget?