Build Android and iOS apps without building everything twice.

Master Kotlin Multiplatform is a practical, hands-on guide to building production-ready Android and iOS applications with Kotlin Multiplatform (KMP) and Compose Multiplatform.

Instead of focusing only on basic demos, this book takes you through the architecture, tools, libraries, and real-world decisions involved in creating a complete multiplatform application.

You'll learn how to share business logic and UI while still taking advantage of the native capabilities of Android and iOS.

• Build and structure a Kotlin Multiplatform project for Android and iOS
• Create shared UI with Compose Multiplatform
• Design scalable multiplatform app architecture
• Build networking layers with Ktor
• Use Coroutines, Flow, StateFlow, and SharedFlow across platforms
• Store data locally with Room KMP
• Implement dependency injection with Koin
• Build repositories and offline-first applications
• Master expect / actual and platform-specific abstractions
• Work with native platform capabilities such as permissions, location, maps, and sensors
• Integrate native Android and iOS UI when shared UI isn't enough
• Implement logging, analytics, crash reporting, and error handling
• Manage configuration, secrets, and feature flags
• Test multiplatform code effectively
• Optimize performance, memory usage, and application size
• Set up CI/CD and release Android and iOS apps
• Understand Kotlin ↔ Swift interoperability
• Incrementally migrate an existing Android application to KMP
• Choose libraries that are safe and practical for multiplatform projects

Kotlin Multiplatform becomes much more interesting when you move beyond a simple shared function.

How should you structure a real app? What belongs in commonMain? When should you use expect/actual? Should the UI be shared? How do you handle native APIs? What happens when you need maps, sensors, permissions, analytics, persistence, or platform-specific UI?

This book focuses on answering those questions.

By the end, you'll understand not only how Kotlin Multiplatform works, but how to make practical architectural decisions when using it in real applications.

This book is especially useful for:

• Android developers moving into Kotlin Multiplatform
• Kotlin developers who want to target Android and iOS
• Mobile developers exploring Compose Multiplatform
• Teams considering KMP for an existing Android application
• Developers who already know KMP basics and want to build production-ready applications

If you already know Kotlin and Android development, you'll feel right at home.

One Kotlin codebase. Two platforms. Native capabilities when you need them.

Master Kotlin Multiplatform and start building Android and iOS applications with a modern, pragmatic approach to shared mobile development.

Modern Android development is no longer just about screens and buttons.

Today's smartphones include sophisticated hardware capable of detecting movement, location, light, sound, biometric authentication, health metrics, and much more.

Unfortunately, most tutorials only scratch the surface.

This book takes a completely different approach.

Instead of reading isolated examples, you'll build 15 practical Android applications, each designed around a different sensor or sensor family.

Throughout the journey you'll learn how to:

• Work with Android sensor APIs
• Build modern UIs using Jetpack Compose
• Process real-time sensor data
• Optimize battery consumption
• Handle lifecycle correctly
• Visualize sensor information
• Test sensor-based applications
• Apply Clean Architecture
• Build production-quality features

Every project introduces new Android concepts while reinforcing best practices used in professional apps.

Who This Book Is For

This book is perfect for:

• Android developers wanting to master hardware integration
• Intermediate developers looking for real-world projects
• Mobile engineers preparing for interviews
• Students learning Android development
• Developers transitioning to Jetpack Compose
• Anyone interested in IoT and mobile sensing
• Software engineers building fitness, navigation, health, or camera applications

What You'll Learn

After finishing this book you'll be able to:

• Understand the Android Sensor Framework
• Read sensor data efficiently
• Handle accelerometer and gyroscope events
• Build digital compass applications
• Detect device orientation
• Create pedometer apps
• Work with GPS and geofencing
• Build CameraX applications
• Capture and analyze microphone input
• Integrate biometric authentication
• Use Android Health APIs
• Combine multiple sensors using Sensor Fusion
• Visualize sensor information with charts
• Optimize battery usage
• Test sensor-heavy applications
• Benchmark sensor performance

What Makes This Book Different?

Instead of small code snippets, this book focuses on complete applications.

Every chapter includes:

• Project architecture
• Step-by-step implementation
• Production-ready code
• Best practices
• Common mistakes
• Performance optimization
• Modern APIs
• Clean Architecture
• MVVM
• Jetpack Compose
• Testing strategy

Table of Contents

Part I — Android Sensor Fundamentals

Project: PhoneCheckup

Understand how Android communicates with device hardware and build an application that inspects every sensor available on a device.

Part II — Motion & Position

Project: DriveSafe

Learn Accelerometer and Gyroscope APIs by detecting movement, acceleration, and driving behavior.

Project: ProCompass

Build a fully functional digital compass using the Magnetometer and Orientation sensors.

Part III — Environmental Awareness

Project: SleepComfort

Measure ambient light, pressure, and temperature to improve user comfort.

Project: SmartEtiquette

Automatically react when the phone is placed near the user's face or pocket.

Part IV — Activity Tracking

Project: WalkMate

Create a modern pedometer application that counts daily steps and visualizes activity.

Project: ParkPin

Build a smart parking assistant with location tracking and geofence notifications.

Part V — Camera & Audio

Project: DocPocket

Create a document scanner using CameraX with modern image capture APIs.

Project: BabySentry

Monitor environmental sounds and detect important audio events.

Part VI — Security & Health

Project: AppLock

Protect applications using fingerprint and biometric authentication.

Project: MorningVitals

Integrate health-related data to build wellness applications.

Part VII — Advanced Sensors

Project: FallGuard

Combine multiple sensors to detect falls and complex device movements.

Project: MyDay

Transform raw sensor streams into meaningful dashboards and charts.

Project: FlexMode

Adapt applications for foldable Android devices and posture changes.

Part VIII — Production Ready

Project: SensorBench

Learn how to test sensor applications, benchmark performance, and ensure reliability across devices.

Why Read This Book?

✔ Build 15 complete Android projects

✔ Learn modern Android development

✔ Master Kotlin

✔ Master Jetpack Compose

✔ Learn CameraX

✔ Work with GPS

✔ Build Health applications

✔ Learn Sensor Fusion

✔ Improve performance

✔ Production-ready architecture

✔ Real-world examples

✔ Beginner-friendly explanations

✔ Intermediate and advanced techniques

✔ Best practices from industry experience

Requirements

To get the most from this book you should have:

• Basic Kotlin knowledge
• Basic Android Studio experience
• Familiarity with Android development fundamentals

No prior experience with Android sensors is required.

Technologies Covered

• Kotlin
• Jetpack Compose
• Android Sensor Framework
• CameraX
• Google Maps
• Location Services
• Geofencing API
• Biometric API
• Android Health APIs
• Material 3
• Coroutines
• Flow
• ViewModel
• Clean Architecture
• MVVM
• Dependency Injection
• Unit Testing
• Benchmarking

Included Projects

Project

What You'll Build

PhoneCheckup

Device sensor inspector

DriveSafe

Motion detection app

ProCompass

Digital compass

SleepComfort

Environmental monitor

SmartEtiquette

Proximity automation

WalkMate

Step tracker

ParkPin

GPS parking assistant

DocPocket

Document scanner

BabySentry

Audio monitoring app

AppLock

Biometric authentication

MorningVitals

Health dashboard

FallGuard

Fall detection system

MyDay

Sensor analytics dashboard

FlexMode

Foldable-aware application

SensorBench

Performance benchmarking tool

Frequently Asked Questions

Yes. The book starts with Android sensor fundamentals before progressing to advanced topics.

All projects use Jetpack Compose and modern Android APIs.

Yes. Every chapter builds a complete real-world application.

Absolutely. Projects follow modern architecture principles with maintainable, scalable code.

Most projects can be tested on a real Android device. Some sensors may not be available on emulators.