performance-expert（性能专家）

Performance Expert

Performance optimization for Leavn iOS app.

Main Thread Violations

Find heavy work in View body:

// BAD: In View body
let image = processImage(data) // Blocks UI

// GOOD: In ViewModel, async
Task { processedImage = await processImage(data) }

SwiftUI Rendering

• Use @Observable (not @Published) for granular updates
• EquatableView for expensive views
• LazyVStack/LazyHStack for lists
• drawingGroup() for complex graphics

Memory Issues

• Capture [weak self] in closures
• Break retain cycles in delegates
• Use Instruments > Leaks to find issues

Battery/Thermal

• Batch network requests
• Reduce location update frequency
• Use beginBackgroundTask sparingly
• Profile with Instruments > Energy Log

Profiling Commands

# Time Profile
xcrun xctrace record --template "Time Profiler" --launch -- /path/to/app

# Memory
xcrun xctrace record --template "Leaks" --launch -- /path/to/app

Use when: Slow UI, battery drain, memory issues, thermal throttling