Where should verbose logging code be added in an iOS app?

Adding verbose logging code in the AppDelegate is an appropriate choice because the AppDelegate is the central point of control and coordination for an iOS application. It is responsible for handling application-level events, such as application launch, transitions to the background, and receiving notifications.

By placing verbose logging code in the AppDelegate, you can capture important lifecycle events and global state changes throughout the app's execution. This makes it easier to track the app's behavior in a centralized manner, allowing for efficient debugging and performance monitoring.

In contrast, logging within specific ViewControllers or components like MainViewController may limit the scope of your logging to particular user interactions or views, rather than providing a holistic view of the application’s state and transitions. Additionally, placing this code in NotificationService is not ideal, as that component is primarily focused on handling push notifications rather than application lifecycle events.