Mobile App Logging Explained: A Complete Beginner's Guide

What is Mobile App Logging?

Mobile app logging is the practice of recording events, errors, and user actions that occur within your mobile application. Think of it as your app's flight recorder—capturing everything that happens so you can understand user behavior, debug issues, and monitor performance even after your app ships to production.

iOS (Swift) Example

import os.log

class Logger {
    static let shared = Logger()
    private let logger = OSLog(subsystem: "com.yourapp", category: "general")
    
    func info(_ message: String) {
        os_log("%{public}@", log: logger, type: .info, message)
    }
    
    func error(_ message: String) {
        os_log("%{public}@", log: logger, type: .error, message)
    }
}

// Usage
Logger.shared.info("User opened profile screen")
Logger.shared.error("Failed to fetch user data: \(error.localizedDescription)")

Android (Kotlin) Example

import android.util.Log

object Logger {
    private const val TAG = "MyApp"
    
    fun info(message: String) {
        Log.i(TAG, message)
    }
    
    fun error(message: String, throwable: Throwable? = null) {
        Log.e(TAG, message, throwable)
    }
}

// Usage
Logger.info("User opened profile screen")
Logger.error("Failed to fetch user data", exception)