Advanced Catalyst Example
This is an example of a Catalyst app using a three-column layout, with a primary toolbar.
It includes topics such as:
- Drag & drop reordering of the sidebar items
 - Scaling UI metrics between Mac Idiom and iPad Idiom
 - Using Codable to load a data store from disk and present it
 - Using an AppKit bundle to access APIs not available to Catalyst, like NSSearchToolbarItem
 - Mixing a SwiftUI detail view into a UIKit app structure
 - Providing a Credits file for your About window
 
