Mobile App Debugging

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

iOS Debugging (Xcode)

// 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)

// 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

// 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

// 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