SwiftUI Performance
Master SwiftUI performance optimization using the new SwiftUI Instrument in Instruments 26.
When to use: App feels less responsive, animations stutter, scrolling performance issues, profiling reveals SwiftUI bottlenecks
Key Features
- New SwiftUI Instrument walkthrough – 4 track lanes, color-coding system, integration with Time Profiler
- Cause & Effect Graph – Visualize data flow and dependencies to eliminate unnecessary updates
- Problem 1: Long View Body Updates
- Identifying long updates with Instruments
- Time Profiler integration for finding bottlenecks
- Common expensive operations (formatter creation, calculations, I/O, image processing)
- Verification workflows
- Problem 2: Unnecessary View Updates
- AttributeGraph and dependency tracking
- Granular dependencies with per-item view models
- Environment updates performance implications
- Performance Optimization Checklist – Systematic approach from profiling setup through verification
- Real-world impact examples from WWDC's Landmarks app
Requirements: Xcode 26+, iOS 26+ SDK for profiling
WWDC References
Philosophy: Ensure your view bodies update quickly and only when needed to achieve great SwiftUI performance.
Example Prompts
These are real questions developers ask that this skill answers:
"My app has janky scrolling and animations stutter." → Shows how to use the new SwiftUI Instrument to identify if SwiftUI is the bottleneck
"I see orange/red bars in the SwiftUI Instrument showing long updates." → Covers Cause & Effect Graph patterns that show data flow and which state changes trigger expensive updates
"Some views are updating way too often even though their data hasn't changed." → Demonstrates unnecessary update detection and Identity troubleshooting with visual timeline
"I have large data structures and complex view hierarchies." → Covers performance patterns: breaking down hierarchies, minimizing body complexity, @Sendable optimization
"We have a performance deadline. What's slow in SwiftUI?" → Provides decision tree for prioritizing optimizations with professional guidance for trade-offs