This demo application uses the MVVM architecture. It demonstrates dependency injection, and uses no singletons. There is a simple API client that is responsible for creating a URL query to download only the data we need to display, i.e, food trucks in operation at the present time (in the San Francisco time zone). The API client uses modern Swift concurrency to make the network call on a background thread, and deliver the results (or throw) without the use of a complection block, future/promise, etc. The FoodTrucksViewModel is a @MainActor, and therefore it delivers its results to the view controller on the main thread for updating the UI. The results are kept in a CurrentValueSubject so that subscribers can be notified when the data has been downloaded, and then access that data at-will. The FoodTrucksViewController is a parent view controller that can switch between its two child view controllers, which display the list and map. It injects its view model into its child view controllers so that the data can be shared. All views are UIKit and use auto layout. Some are constructed in a storyboard, and others are built fully in code.
This application was built to specific design instructions for demonstration purposes. However, if I were building this app for the App Store, I would use a UITabBarController for switching between the list and map views, rather than a UIBarButtonItem. I would limit the amount of data shown in the list view as it can become quite long, and instead let the user navigate to a details view for the info. I would implement convenience features, such as the ability to search by name, menu items, etc. The list could be sortable by distance from the user's current location. The map annotations would show the name of their food truck. The user should be able to retrieve directions to a truck. A truck should be easily shareable with friends via messaging apps. Trucks could have a star rating system. If possible, a separate server store could be used to retrieve pictures of the trucks or vendor's logos. The app would have a companion web-based version. It would also let the user access data for more cities than just San Francisco. Finally, for a real managed project, the code should be unit-tested.