swiftui-expert-skill_skill

Overview

This skill helps write, review, and improve SwiftUI code with modern, performance-conscious practices. It focuses on correct state management, view composition, Swift concurrency, and optional iOS 26+ Liquid Glass styling. Use it to adopt modern APIs, reduce update fan-out, and ensure platform-safe fallbacks.

How this skill works

The skill inspects SwiftUI views for proper property wrapper selection, modern API usage, and efficient view structure. It flags performance anti-patterns, enforces stable list identities, and suggests concurrency and formatting improvements. Liquid Glass advice is provided only when the user requests iOS 26+ styling and includes availability gating and sensible fallbacks.

When to use it

• Building a new SwiftUI feature with modern APIs and concurrency
• Refactoring views to reduce unnecessary state updates and improve diffing
• Reviewing PRs for state, navigation, and list stability issues
• Adopting iOS 26+ Liquid Glass visuals with fallback handling
• Optimizing performance hotspots like lists, onChange handlers, and hot paths

Best practices

• Prefer @Observable over ObservableObject for new shared state and mark with @MainActor when appropriate
• Keep @State and @StateObject private; use @Binding only when a child must modify parent state
• Extract complex UI into small subviews to improve diffing and readability; avoid heavy logic inside body
• Use modern API replacements (foregroundStyle, NavigationStack, Tab API, ImageRenderer) and gate iOS 26+ features with #available
• Pass only needed values to child views, avoid inline filtering in ForEach, and use stable IDs for list elements
• Apply Liquid Glass after layout modifiers and wrap related elements in GlassEffectContainer when requested

Example use cases

• Refactor a feed view to use LazyVStack, stable ForEach IDs, and prefiltered data to prevent list thrash
• Convert an ObservableObject-based view model to @Observable with @MainActor and bind it via @Bindable in child views
• Replace deprecated modifiers (cornerRadius, foregroundColor) with modern equivalents and adjust accessibility labels
• Implement a sheet using .sheet(item:) where the sheet owns its actions and calls dismiss() internally
• Prototype Liquid Glass UI for iOS 26+: use glassEffect with #available and provide material fallback