SwiftUI Standards

Priority: P0

Implementation Guidelines

State Management

• @State: @State for data owned by the view (e.g., toggle, text input). Private to the view.
• @Binding: @Binding for data passed down from a parent to a child. Two-way connection.
• @ObservedObject: @ObservedObject when receiving an instance from an external source.
• @StateObject: @StateObject when the view is creating the object instance. View owns lifecycle.
• @EnvironmentObject: inject data into the view's hierarchy via

  .environmentObject()

  . Shared across view hierarchy.

View Composition

• Extract Subviews: Keep views small (<200 lines). Extract reusable components.
• View Modifiers: Chain modifiers for styling (

  .font()

  ,

  .padding()

  ).
• Custom Modifiers: Create

  ViewModifier

  for reusable styles.

Performance

• Avoid Heavy Computation: Use

  @State

  +

  .task()

  for async work.
• Equatable: Conform views to

  Equatable

  to prevent unnecessary re-renders.
• LazyStacks: Use

  LazyVStack

  /

  LazyHStack

  when displaying a large number of views in a scrolling container to load them only as they appear.

Anti-Patterns

• No @ObservedObject for owned objects: Use @StateObject.
• No logic in body: Move to computed properties or methods.
• No ! in View: Use if-let or nil coalescing.

References

• State & Binding