how is UIContentConfiguration composable?

UIContentConfiguration is composable in several ways, as highlighted in the What’s new in UIKit session. Here are the key points:

1. Automatic Trait Tracking: UIContentConfiguration and UIBackgroundConfiguration now take advantage of the new list environment trait. This means that when updated for a new state, they adjust their properties to match the list environment from the configuration state's trait collection. This removes the need to know the style of the list when configuring a cell, simplifying the code.

2. Automatic Updates: The existing cell subtitle, cell, and value cell configurations now automatically update their appearance based on the list environment trait. New header and footer configurations do the same, ensuring that the appearance is consistent and automatically updated.

3. New Constructors: For UIBackgroundConfiguration, there are three new constructors: list cell, list header, and list footer. These configurations also update their appearance automatically from the list environment trait.

These features make UIContentConfiguration highly composable, allowing for flexible and dynamic UI updates without manual reconfiguration. This is particularly useful in applications like the Files app, which uses different styles for lists depending on the context (e.g., portrait vs. landscape).

For more details, you can refer to the List improvements chapter in the "What’s new in UIKit" session.