# 12. App Launch Time Optimization

meta:
  id: ios-production-12
  feature: ios-production
  priority: P2
  depends_on: []
  tags: [performance, launch, production]

objective:
- Optimize app launch time to under 2 seconds for cold starts and under 1 second for warm starts

deliverables:
- Launch time measurement and baseline
- Optimized app initialization
- Lazy loading of heavy components
- Reduced binary size

steps:
1. Measure current launch time:
   - Use Xcode Metrics Organizer
   - Use os_signpost for custom timing
   - Measure cold start (first launch after reboot)
   - Measure warm start (subsequent launches)
   - Establish baseline metrics
2. Optimize app delegate:
   - Minimize work in application(_:didFinishLaunchingWithOptions)
   - Defer non-critical initialization
   - Move heavy setup to background threads
   - Avoid blocking main thread
3. Lazy load heavy components:
   - Defer VoicePrint model loading until needed
   - Defer document scanner initialization
   - Lazy load WebView components
   - Load dashboard data after UI appears
4. Optimize storyboards/XIBs:
   - Remove unused storyboards
   - Minimize view controller initialization
   - Use code-based UI where faster
5. Reduce binary size:
   - Strip debug symbols from release builds
   - Remove unused resources and assets
   - Compress images in asset catalog
   - Enable dead code stripping
6. Optimize framework loading:
   - Link frameworks statically where possible
   - Reduce dynamic framework count
   - Prelink common frameworks
7. Add launch screen optimization:
   - Simple, static launch screen
   - Match first screen of app
   - No animations or complex layouts

tests:
- Performance: Measure launch time on iPhone 12
- Stress: Launch app 100 times, average time <2s
- Memory: No memory spikes during launch

acceptance_criteria:
- Cold launch time <2 seconds on iPhone 12
- Warm launch time <1 second on iPhone 12
- Launch screen visible for <500ms
- No blocking operations on main thread during launch
- Binary size <100MB (App Store limit is much higher)
- Heavy components loaded lazily after launch
- Launch time measured and tracked in CI
- No crashes during launch under memory pressure

validation:
- Xcode Metrics → cold start <2s, warm <1s
- Instruments Time Profiler → no long blocking calls on main thread
- Physical device test → feels instant
- App Store Connect → binary size acceptable

notes:
- Launch time is critical for App Store review and user retention
- iOS may terminate apps with launch times >20 seconds
- Use pre-warmed launches for more accurate measurement
- Test on oldest supported device (iPhone SE 2nd gen or similar)