AgentSkillsCN

Swift SwiftUI

状态管理、视图生命周期与属性包装器的规范

SKILL.md
--- frontmatter
name: Swift SwiftUI
description: Standards for State Management, View Lifecycle, and Property Wrappers
metadata:
  labels: [swift, swiftui, state, binding, view]
  triggers:
    files: ['**/*.swift']
    keywords: ['@State', '@Binding', '@ObservedObject', 'View', 'body']

SwiftUI Standards

Priority: P0

Implementation Guidelines

State Management

  • •@State: Private UI state owned by the view (e.g., toggle, text input).
  • •@Binding: Two-way connection to parent's @State.
  • •@ObservedObject: Reference to external observable object.
  • •@StateObject: View owns the lifecycle of the object.
  • •@EnvironmentObject: Shared data 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 for large lists.

Anti-Patterns

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

References