John Paczkowski:

A tentpole feature of the new iPhones are improved camera systems that are larger than the cameras in the devices that preceded them. The iPhone 7 now has the optical image stabilization feature previously reserved for its larger Plus siblings. And the iPhone 7 Plus has two complete camera systems side by side — one with a fixed wide-angle lens, the other with a 2x zoom telephoto lens. At the top of both devices is something called the “driver ledge” — a small printed circuit board that drives the iPhone’s display and its backlight. Historically, Apple placed it there to accommodate improvements in battery capacity, where it was out of the way. But according to Riccio, the driver ledge interfered with the iPhone 7 line’s new larger camera systems, so Apple moved the ledge lower in both devices. But there, it interfered with other components, particularly the audio jack.

So the company’s engineers tried removing the jack.

In doing so, they discovered a few things. First, it was easier to install the “Taptic Engine” that drives the iPhone 7’s new pressure-sensitive home button, which, like the trackpads on Apple’s latest MacBook, uses vibrating haptic sensations to simulate the feeling of a click — without actually clicking. (Did we mention that Apple killed the physical home button too?) Taptic Engine vibrations will also be used to deliver feeling specific notifications — hitting the end of a scrolled page, for example. And because Apple has given developers an API for it, an awful lot of other stuff as well — particularly in games.

“You can’t make it feel like there’s an earthquake happening, but the range of customization lets you do an awful lot,” Apple SVP Phil Schiller explains. “With every project there are things that surprise you with the meaning they take on as you start to use them. The Taptic Engine API is one of them. It turned into a much bigger thing than we ever thought it would be. It really does transform the experience for a lot of software. You’ll see.”
Second, there was an unforeseen opportunity to increase battery life. So the battery in the iPhone 7 is 14% bigger than the one in its predecessor, and in the iPhone 7 Plus, it’s 5% bigger. In terms of real-world performance gains, that’s about an additional two hours and one hour, respectively. Not bad.