ios-swiftui-patterns

SwiftUI state management uses @State for local view state, @Binding to pass state between views, @StateObject for observable models, and @EnvironmentObject to share data app-wide. Choose based on scope: local changes use @State, parent-child communication uses @Binding, and cross-app data uses @EnvironmentObject or the modern @Observable pattern.

@StateObject manages lifecycle and retains the object across view redraws, making it ideal for creating observable models within a view. @ObservedObject observes an object passed in from elsewhere but doesn't manage its lifetime, risking premature deallocation. Use @StateObject when you own the model, @ObservedObject when receiving it as a parameter.

Compose views by breaking the UI into smaller, focused view structs and extract common styling into custom view modifiers. SwiftUI favors value types and modifier chains, allowing you to build maintainable interfaces by combining simple, reusable components and applying modifiers functionally rather than imperatively.

SwiftUI state management and declarative UI patterns apply across all Apple platforms—iOS, macOS, watchOS, and tvOS. The same @State, @Binding, @EnvironmentObject, and @Observable approaches work consistently, though platform-specific layout and navigation considerations like NavigationStack adapt to each device type.

Use lifecycle-aware async tasks with @StateObject model classes or modern task modifiers to manage async work tied to view lifecycle. SwiftUI automatically cancels tasks when views disappear, preventing crashes and memory leaks while keeping data flow predictable and declarative.

Use NavigationStack for navigation flow and @State to control sheet and alert presentation. Bind state properties to sheet and alert modifiers to declaratively manage UI presentation, keeping navigation logic separate from view rendering and supporting predictable back-button and dismissal behavior.