Replace isLoading With This SwiftUI Pattern

A practical SwiftUI tutorial demonstrating how to replace simple boolean `isLoading` flags with a generic `ViewState` enum pattern. The pattern covers four states: loading, success, empty, and error. The tutorial walks through creating the enum with a generic type parameter, wiring it to a SwiftUI view using `@State` and `.task`, and then refactoring the logic into a reusable `StateView` component that accepts content and retry closures, making async data-fetching views cleaner and more maintainable.