SwiftUI Advanced
Advanced SwiftUI patterns for gesture composition, adaptive layouts, architecture decisions, and performance optimization.
Reference Loading Guide
ALWAYS load reference files if there is even a small chance the content may be required. It's better to have the context than to miss a pattern or make a mistake.
Reference Load When Gestures Composing multiple gestures, GestureState, custom recognizers Adaptive Layout ViewThatFits, AnyLayout, size classes, iOS 26 free-form windows Architecture MVVM vs TCA decision, State-as-Bridge, property wrapper selection Performance Instruments 26, view body optimization, unnecessary updates Core Workflow Identify pattern category from user's question Load relevant reference for detailed patterns and code examples Apply pattern following the decision trees and anti-patterns Verify using provided checklists or profiling guidance Decision Trees Gesture Composition Both gestures at same time? -> .simultaneously One must complete before next? -> .sequenced Only one should win? -> .exclusively Layout Adaptation Pick best-fitting variant? -> ViewThatFits Animated H/V switch? -> AnyLayout Need actual dimensions? -> onGeometryChange Architecture Selection Small app, Apple patterns? -> @Observable + State-as-Bridge Complex presentation logic? -> MVVM with @Observable Rigorous testability needed? -> TCA Common Mistakes
Gesture composition order matters — .simultaneously and .sequenced have different trigger timing. Swapping them silently changes behavior. Understand gesture semantics before using.
ViewThatFits over-used — ViewThatFits remeasures on every view change. For animated H/V switches, use AnyLayout instead. Use ViewThatFits only for static variant selection.
onGeometryChange triggering unnecessary updates — Reading geometry changes geometry, which triggers updates, which changes geometry... circular. Use .onGeometryChange only with proper state management to avoid loops.
Architecture mismatch mid-project — Starting with @Observable + State-as-Bridge then realizing you need TCA is expensive. Choose architecture upfront based on complexity (small app = @Observable, complex = TCA).
Ignoring view body optimization — Computing expensive calculations in view body repeatedly kills performance. Move calculations to properties or models. Profile with Instruments 26 before optimizing prematurely.