iPhone: The Missing Manual, 3rd Edition

The Crazy Future of Apps

There are enough good new features for you, the customer, in iPhone 3.0 to fill a book—and you're reading it. But the really insane part is the long list of features available to programmers—behind-the-scenes stuff you'll never see until some mind-blowing new apps arrive.

It was cool when games like Super Monkey Ball and Cro-Mag Rally and Labyrinth took advantage of the iPhone's accelerometer (tilt sensor). That is, you tip and turn the whole phone to guide your monkey/race car/whatever through the course. But now, iPhone apps can use the camera, the compass, Wi-Fi, GPS, and software features like these:

• "Push" notifications. You can do two things at once on the iPhone—talk on the phone while you check your calendar, listen to music while watching a slideshow, download an app while you play a game. But in general, it's not a multitasking operating system; you can't have several programs running at once.

  Now, however, a program you're not running can alert you—that you have a new chat partner, a new Twitter response, and so on—with a sound, a message or a little "'badge" on the icon (like Mail has now).

• Peer-to-peer Bluetooth. Two iPhones can communicate wirelessly—for head-to-head games and heaven knows what else.

• In-app purchases. You can buy new issues of a magazine, new eBooks inside a reader program, additional game levels, and so on, right from within the program itself. You don't have to lumber off to the App Store.

• Turn-by-turn directions. Several companies ...