Problem Statement
How does the Combine framework integrate with SwiftUI for reactive data flows?
Explanation
Combine is Apple’s reactive framework and in SwiftUI you often define a view model conforming to `ObservableObject`, with properties annotated with `@Published`. When these change, SwiftUI views subscribed via `@ObservedObject` or `@EnvironmentObject` automatically refresh. This pattern is frequently discussed in iOS/SwiftUI interviews.