Book excerpt: There may be “an app for that,” but every app starts as an idea. Ideas can come from anyone—designers or developers, marketing managers or CEOs—and this book is about bringing those ideas to life. iOS is a remarkable platform, both from a technology standpoint and as a pure business opportunity. With over 10 billion apps downloaded through the iTunes App Store, and over 50 million new iOS devices expected to ship in 2011, no other platform puts big business and individual developers on a level playing field like iOS does. Needless to say, if you have an idea for an app, now is the time to make it happen. Whether you’re a designer or a developer, this book will help you: Create basic user interface elements Understand navigation metaphors and practices Design for multiple devices Customize system UI elements Incorporate system-provided and custom animations Use touch- and motion-based gestures Create UIViews and UIViewControllers using Core Graphics Avoid rejection by the iTunes App Store