Although developers have covered a lot of topics and activities with more than 725,000 apps for iOS devices, they have yet to tap the riches of location-based and augmented reality applications. This book shows you how to use iPhone's sensors -- the three-axis accelerometer, GPS, digital compass, and camera -- to build cutting-edge location-aware apps that interact with the physical world. You can easily access iPhone's sensors, but interpreting the data you get back from them is tricky. Harder still is combining the input from several sensors with outside data sets. This book shows you how to put it all together. It's ideal for experienced iPhone programmers, game programmers, augmented reality programmers, and geo hackers. Get an introduction to the hot topic of programming iPhone's built-in sensors Learn how to create sensor-aware apps that respond to a user's location Understand the basics of augmented reality programming Build apps that combine data from the accelerometer, GPS, digital compass, and camera Connect iOS devices to Arduino and connect to external sensors This book is based on a collection of books that was published earlier, along with additional material not available elsewhere. The books in this collection are Augmented Reality in iOS, Geolocation in iOS, iOS Sensor Apps with Arduino, and Basic Sensors in iOS.