Centralized Logging

The React Native Biometrics library includes a comprehensive centralized logging system that helps developers debug issues, monitor performance, and track biometric operations in their applications.

Features

• Multiple Log Levels: DEBUG, INFO, WARN, ERROR
• Contextual Logging: Each log entry includes context information
• Configurable Output: Customize log format, prefix, and visibility
• Log Storage: Store logs in memory for analysis
• Debug Mode Integration: Automatically enables logging when debug mode is active
• Performance Optimized: Minimal overhead when logging is disabled

Quick Start

Basic Usage

import { enableLogging, setLogLevel, LogLevel, isSensorAvailable } from '@sbaiahmed1/react-native-biometrics';

// Enable logging
enableLogging(true);
setLogLevel(LogLevel.DEBUG);

// All biometric operations will now be logged
const sensorInfo = await isSensorAvailable();

Debug Mode Integration

import { setDebugMode } from '@sbaiahmed1/react-native-biometrics';

// Enable debug mode (automatically enables logging)
await setDebugMode(true);

// All operations will be logged with DEBUG level
// Disable debug mode to reduce logging
await setDebugMode(false);

Configuration

Logger Configuration

import { configureLogger, LogLevel } from '@sbaiahmed1/react-native-biometrics';

configureLogger({
  enabled: true,
  level: LogLevel.INFO,
  prefix: '[MyApp-Biometrics]',
  includeTimestamp: true,
  includeContext: true
});

Configuration Options

Option	Type	Default	Description
enabled	boolean	false	Enable/disable logging
level	LogLevel	INFO	Minimum log level to output
prefix	string	[ReactNativeBiometrics]	Prefix for all log messages
includeTimestamp	boolean	true	Include timestamp in log output
includeContext	boolean	true	Include context information
useColors	boolean	true	Enable colored console output

Log Levels

LogLevel Enum

enum LogLevel {
  DEBUG = 0,  // Detailed debugging information
  INFO = 1,   // General information
  WARN = 2,   // Warning conditions
  ERROR = 3,  // Error conditions
  NONE = 4    // Disable all logging
}

Level Descriptions

• DEBUG: Detailed information for debugging, including function entry/exit and parameter values
• INFO: General operational information about successful operations
• WARN: Warning conditions that don't prevent operation but should be noted
• ERROR: Error conditions that prevent normal operation
• NONE: Completely disable logging

Log Management

Retrieving Logs

import { getLogs, LogLevel, LogEntry } from '@sbaiahmed1/react-native-biometrics';

// Get all stored logs
const allLogs: LogEntry[] = getLogs();

// Filter logs by level
const errorLogs = allLogs.filter(log => log.level === LogLevel.ERROR);

// Filter logs by context
const authLogs = allLogs.filter(log => log.context === 'authenticateWithOptions');

Clearing Logs

import { clearLogs } from '@sbaiahmed1/react-native-biometrics';

// Clear all stored logs
clearLogs();

Log Entry Structure

interface LogEntry {
  timestamp: string;    // ISO timestamp
  level: LogLevel;      // Log level
  message: string;      // Log message
  context?: string;     // Function/operation context
  data?: any;          // Additional data
  error?: Error;       // Error object (for error logs)
}

Advanced Usage

Color Support

The logging system supports colored console output to improve readability:

• DEBUG: Gray text for debug information
• INFO: Blue text for informational messages
• WARN: Yellow/Orange text for warnings
• ERROR: Red text for errors
• Prefix: Cyan text for the logger prefix
• Timestamps/Context: Dimmed text for metadata

// Enable colors (default)
configureLogger({ useColors: true });

// Disable colors for production or unsupported terminals
configureLogger({ useColors: false });

// Note: colors are not auto-detected — set useColors: false in environments
// that don't support ANSI codes

Custom Log Analysis

import { getLogs, LogLevel } from '@sbaiahmed1/react-native-biometrics';

function analyzePerformance() {
  const logs = getLogs();
  
  // Group by operation
  const operationStats = logs.reduce((stats, log) => {
    if (log.context) {
      if (!stats[log.context]) {
        stats[log.context] = { total: 0, errors: 0 };
      }
      stats[log.context].total++;
      if (log.level === LogLevel.ERROR) {
        stats[log.context].errors++;
      }
    }
    return stats;
  }, {} as Record<string, { total: number; errors: number }>);
  
  return operationStats;
}

Production Monitoring

import { configureLogger, LogLevel, getLogs } from '@sbaiahmed1/react-native-biometrics';

// Production configuration - only log warnings and errors
configureLogger({
  enabled: true,
  level: LogLevel.WARN,
  prefix: '[BiometricsSDK]',
  includeTimestamp: true,
  includeContext: true,
  useColors: false // Disable colors in production
});

// Monitor for critical issues
function checkForCriticalIssues() {
  const logs = getLogs();
  const recentErrors = logs
    .filter(log => log.level === LogLevel.ERROR)
    .filter(log => {
      const logTime = new Date(log.timestamp).getTime();
      const oneHourAgo = Date.now() - (60 * 60 * 1000);
      return logTime > oneHourAgo;
    });
  
  if (recentErrors.length > 5) {
    // Alert: High error rate detected
    console.warn('High biometric error rate detected:', recentErrors.length);
  }
}

Integration Examples

React Native Component

import React, { useEffect, useState } from 'react';
import { View, Text, Button, ScrollView } from 'react-native';
import { 
  isSensorAvailable, 
  enableLogging, 
  setLogLevel, 
  LogLevel,
  getLogs,
  LogEntry 
} from '@sbaiahmed1/react-native-biometrics';

const BiometricComponent: React.FC = () => {
  const [logs, setLogs] = useState<LogEntry[]>([]);
  
  useEffect(() => {
    // Enable logging for development
    if (__DEV__) {
      enableLogging(true);
      setLogLevel(LogLevel.DEBUG);
    }
  }, []);
  
  const handleBiometricCheck = async () => {
    try {
      const result = await isSensorAvailable();
      
      // Update logs display
      setLogs(getLogs());
      
      return result;
    } catch (error) {
      // Logs will automatically capture the error
      setLogs(getLogs());
      throw error;
    }
  };
  
  return (
    <View>
      <Button title="Check Biometrics" onPress={handleBiometricCheck} />
      
      {__DEV__ && (
        <ScrollView style={{ maxHeight: 200 }}>
          {logs.map((log, index) => (
            <Text key={index} style={{ fontSize: 10 }}>
              [{LogLevel[log.level]}] {log.message}
            </Text>
          ))}
        </ScrollView>
      )}
    </View>
  );
};

Error Reporting Integration

import { getLogs, LogLevel } from '@sbaiahmed1/react-native-biometrics';
import crashlytics from '@react-native-firebase/crashlytics';

function reportBiometricIssue(error: Error) {
  // Get recent biometric logs
  const logs = getLogs();
  const recentLogs = logs.slice(-10); // Last 10 logs
  
  // Format logs for crash reporting
  const logContext = recentLogs.map(log => 
    `[${LogLevel[log.level]}] ${log.timestamp} ${log.context}: ${log.message}`
  ).join('\n');
  
  // Report to crash analytics with context
  crashlytics().recordError(error);
  crashlytics().setAttributes({
    biometric_logs: logContext,
    error_context: 'biometric_operation'
  });
}

Best Practices

Development

1. Enable Debug Logging: Use LogLevel.DEBUG during development
2. Monitor All Operations: Enable logging for all biometric operations
3. Regular Log Review: Periodically review logs for patterns

// Development setup
if (__DEV__) {
  enableLogging(true);
  setLogLevel(LogLevel.DEBUG);
}

Production

1. Limit Log Levels: Use LogLevel.WARN or LogLevel.ERROR only
2. Monitor Critical Issues: Set up alerts for error patterns
3. Regular Cleanup: Clear logs periodically to manage memory

// Production setup
configureLogger({
  enabled: true,
  level: LogLevel.WARN,
  includeTimestamp: true,
  includeContext: true,
  useColors: false // Disable colors in production
});

// Clear logs daily
setInterval(() => {
  clearLogs();
}, 24 * 60 * 60 * 1000);

Performance

1. Disable When Not Needed: Turn off logging in production if not required
2. Use Appropriate Levels: Higher log levels have less performance impact
3. Limit Log Storage: Logs are stored in memory, so clear them regularly

Troubleshooting

Common Issues

Logs Not Appearing

• Ensure logging is enabled: enableLogging(true)
• Check log level: setLogLevel(LogLevel.DEBUG)
• Verify console output in your development environment

Too Many Logs

• Increase log level: setLogLevel(LogLevel.INFO) or higher
• Disable debug mode: setDebugMode(false)
• Clear logs regularly: clearLogs()

Performance Issues

• Reduce log level in production
• Disable logging entirely if not needed
• Clear logs more frequently

Debug Commands

// Check current logger configuration
import { logger, getLogs, LogLevel } from '@sbaiahmed1/react-native-biometrics';
console.log('Logger config:', logger.getConfig());

// Get log statistics
const logs = getLogs();
console.log('Total logs:', logs.length);
console.log('Error logs:', logs.filter(l => l.level === LogLevel.ERROR).length);

API Reference

Functions

• enableLogging(enabled: boolean): Enable/disable logging
• setLogLevel(level: LogLevel): Set minimum log level
• configureLogger(config: Partial<LoggerConfig>): Configure logger settings
• getLogs(): LogEntry[]: Get all stored logs
• clearLogs(): void: Clear all stored logs

Types

• LogLevel: Enumeration of log levels
• LogEntry: Structure of a log entry
• LoggerConfig: Logger configuration interface

Logger Instance

import { logger } from '@sbaiahmed1/react-native-biometrics';

// Direct logger methods
logger.debug('Debug message', 'context', data);
logger.info('Info message', 'context', data);
logger.warn('Warning message', 'context', data);
logger.error('Error message', 'context', error, data);