Mobile App Debugging

---
name: mobile-app-debugging
description: Mobile app debugging for iOS, Android, cross-platform frameworks. Use for crashes, memory leaks, performance issues, network problems, or encountering Xcode instruments, Android Profiler, React Native debugger, native bridge errors.
---

# Mobile App Debugging

Debug mobile applications across iOS, Android, and cross-platform frameworks.

## iOS Debugging (Xcode)

```swift
// Breakpoint with condition
// Right-click breakpoint > Edit > Condition: userId == "123"

// LLDB commands
po variable          // Print object
p expression         // Evaluate expression
bt                   // Backtrace
```

### Memory Debugging
- Use Memory Graph Debugger to find retain cycles
- Enable Zombie Objects for use-after-free bugs
- Profile with Instruments > Leaks

## Android Debugging (Android Studio)

```kotlin
// Logcat filtering
Log.d("TAG", "Debug message")
Log.e("TAG", "Error", exception)

// Filter: tag:MyApp level:error
```

### Common Issues
- ANR: Check main thread blocking
- OOM: Profile with Memory Profiler
- Layout issues: Use Layout Inspector

## React Native

```javascript
// Remote debugging
// Shake device > Debug JS Remotely

// Console logging
console.log('Debug:', variable);
console.warn('Warning');
console.error('Error');

// Performance Monitor
// Shake > Show Perf Monitor
// Target: 60 FPS, <16ms per frame
```

## Network Debugging

```javascript
// Intercept requests
XMLHttpRequest.prototype._send = XMLHttpRequest.prototype.send;
XMLHttpRequest.prototype.send = function() {
  console.log('Request:', this._url);
  this._send.apply(this, arguments);
};
```

## Debug Checklist

- [ ] Test on physical devices (not just simulators)
- [ ] Test on older device models
- [ ] Simulate slow 3G network
- [ ] Test offline mode
- [ ] Check memory under load
- [ ] Test rotation and safe areas
- [ ] Verify 60 FPS target

## Performance Targets

| Metric | Target |
|--------|--------|
| Frame rate | 60 FPS (16ms/frame) |
| Memory | <100MB |
| App launch | <2 seconds |