iPad Programming A Quick-Start Guide for iPhone Developers

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Copyright 2010 Pragmatic Programmers, LLC. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form, or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior consent of the publisher. Printed in the United States of America. ISBN-10: 1-934356-57-3 ISBN-13: 978-1-934356-57-9 Printed on acid-free paper. B1.0 printing, April 3, 2010 Version: 2010-4-14

Chapter 1

From iPhone to iPad
Before you write a line of code for your iPad app, you need to hold the device in your hands. You need to feel the device melt away as you become immersed in an app. The app you are using gets out of your way as you get involved in an activity it enables. That’s the kind of app we want you to write. We don’t merely want you to write apps that run on an iPad, we want you to write apps that are perfect for the platform. People are going to tell their friends about your app because it delights them when they notice it, and it disappears as they use it. How can that be? Isn’t the iPad just an oversized iPod touch that runs on the same iPhone OS we already know and love? Have we become caught up in the marketing hype generated by Steve Jobs’ famous reality distortion field? No. There is something fundamentally different about this high resolution device with its large display that fits in your hands but not your pocket–a device that you navigate with multi-touch and gestures. Throughout this book, we show you how to build experiences for this new device. We’ll explore the similarities and differences between developing for the iPad and what you’re used to in developing for the iPhone. In fact, we’ll start by creating an iPhone app in this chapter and transform it into an app that runs on your iPad. But first let’s figure out how the iPad fits in your end users’ lives– somewhere between the laptop and the iPhone.

T HE I P AD

AND THE

L APTOP

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1.1 The iPad and the Laptop
Once you’ve checked email or surfed the web on an iPad, your laptop is going to seem bulkier and less portable than it was the minute before you picked up the iPad. Suddenly, you’ll be aware of the amount of space required to house the keyboard, trackpad, hard drive, and battery. On the other hand, your iPad is more constrained. It is not meant to live as a standalone device. It must be synced to a laptop or desktop machine once in a while. It doesn’t have the processing power, memory, or storage of a laptop. It is designed to belong to a single user, with a single app occupying your attention at any given time. The iPad is not meant to be the digital hub that a desktop or laptop becomes. For now, it is a node on the hub, not the center of your digital universe. Most importantly, there is something very different about interacting with the screen by touching it as opposed to having to use a mouse or a trackpad. On the iPad, you use your finger to land planes in Flight Control, paint beautiful images with Brushes, and mark email messages as deleted. If you want to move or guide an object, you put your finger on it and move your finger. The object comes along for the ride. If you want to resize an object, you use two fingers to pinch or zoom. You use your finger to resize, reposition, and crop an image. You zoom in on a web page to better read it, and so that your finger can more easily select the right text box to type into. These gestures have become so natural that it feels strange to use a mouse to select an object and grab handles to resize and reposition. Reaching for the mouse or the trackpad takes us out of the moment. The last important difference between an iPad and a laptop is that you can easily rotate the iPad ninety degrees and get a whole different view of your application. In fact, as an iPad developer, you are asked to consider how best to present your app in both landscape and portrait orientations.

1.2 The iPad and the iPod Touch
The iPad runs iPhone OS. You will use many of the same APIs to write your iPad apps that you use to write apps for the iPhone. So isn’t the iPad just a big iPod touch?

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