WHICH WAY IS UP? As far as the iPhone's concerned, it's all relative. Spin the device any which way, and it keeps up with you, rotating your app's interface so that it's always upright—provided, that is, that you support rotation in your app. But should you?
You're not obliged to offer screen rotation. As you'll see, squeezing your app into a new orientation involves more subtle design considerations than you might at first anticipate. It takes lots of work and careful thinking to show your wares to best effect in both portrait (vertical) and landscape (horizontal) views. Doing a half-hearted job on screen rotation is worse than not doing it at all. The best advice: make your app the best it can be in one orientation—usually portrait—and once you've nailed that, consider whether you might support the other orientation, too.
What's the big deal—it's just a change in screen dimensions, right? That in itself isn't new territory for software designers. Managing variable window sizes in desktop software or wildly different screen resolutions for the Web are familiar challenges. Some of the same considerations apply here, too—how to reflow the layout to fit the new orientation—but a change in rotation also signals a change in the user's mindset. People flip their iPhones with a purpose, and that motivation can suggest significant interface changes between portrait and landscape views. This chapter explores the opportunities of screen rotation and describes how to cope with the pixel-precise practicalities without getting the spins. Pop a Dramamine and let's give your interface a whirl.
Everything starts with portrait orientation. That's what's most comfortable in the hand, and that's how we're used to holding a phone, but most important the iPhone Home screen itself is always in portrait—no landscape option. When you launch an app, that means you always start off holding the phone upright. So what prompts people to flip? What's so special about landscape? Understanding why people turn the screen informs whether it's a feature that would add value to your app.
First, the obvious: some media is simply formatted for landscape, period. Games are commonly landscape-only apps that launch immediately into landscape orientation. Video-heavy apps could logically do the same, too. If your app relies on media or graphics that are strongly tied to one orientation or the other, embrace that format; no need to wedge it into an orientation that doesn't fit. (By the way, people figure out landscape-only apps on their own. If your app has only a single orientation, don't add an alert or extra chrome to remind people to turn the phone on its side. Just launch directly into landscape orientation; the interface itself makes it clear that you have to turn the device.)
Aside from the physical format of the media, there's also a consideration of the amount of attention the media demands. Landscape orientation is well-suited to games and video because the horizontal layout naturally provides a more immersive experience. In part that's because landscape better fills your vision, but more important, it practically requires a two-handed grip. With both of your user's hands occupied, you can be reasonably sure that you've got their full attention. For immersive apps, landscape's two-handedness subtly pulls people into the screen.
For other content, people flip to landscape largely for two reasons: easier reading and easier typing. In user testing and interviews, people say they expect larger text when they flip to landscape. Specifically, they expect that the app will maintain the same column content, scaling the text to fill the wider space. In Safari (and any other app that uses a web view to display content) that's exactly how it works, and it's very likely the source of this particular expectation. To most people, landscape means big text.
Figure 9-2. Portrait (left) and landscape (right) views in Kindle show the exact same text (and in the same font size), but the typography works better in the wider landscape column, with fewer unsightly gaps between words.
The trouble with automatically scaling up the content for landscape is that you show less content on the screen—bigger text, but less of it. User expectations aside, it's more useful to think of the landscape orientation as a way to display content differently, not just bigger. Text-savvy apps like ebook readers Stanza and Kindle, for example, don't resize text when you flip to landscape. Instead, you see the same words, in the same size, but in a wider column. For some people, a wider column means easier reading, too—the type flows better, and the eye doesn't have to jump down to the next line as often.
For apps that trade in words, there's no doubt that offering an option to adjust the size of type is indeed good practice, but it doesn't necessarily require a landscape view to do it. USA Today, for example, decided not to offer a landscape view of its articles. "We believe that when many users request landscape mode, it's because they have been trained by Mobile Safari to expect that rotating makes the text larger," says Rusty Mitchell, creative director for the USA Today app. "Instead, we decided to add an option to adjust the font size in portrait mode."
Figure 9-3. USA Today lets you pinch to change the font size, and a size meter appears onscreen while you make the change. The size can also be changed in the app's settings.
Others flip to landscape for easier typing and find the wider keyboard to be less error prone. Not everyone thinks this way, however, with many users saying that the portrait keyboard's compact layout lets them type faster than landscape does. This one's simply a matter of ergonomic preference. No matter which keyboard someone prefers, though, that preference is almost always strongly held. A landscape typist finds portrait unbearable, and vice versa. For apps that go heavy on writing and messaging, it's good practice to support both landscape and portrait keyboards.
Demographics matter here, too. In my own user interviews, younger people show a greater preference for thumb typing on landscape keyboards. In fact, teens and young adults are typically at ease moving between orientations and are, in general, more comfortable than older people with the landscape view. That's likely, at least in part, because they're more accustomed to using landscape-format gadgets (hello, game consoles). For that matter, they're just as likely to consider the iPhone—and especially the iPod Touch—as a game console, too. Older users meanwhile tend to think of the device more literally as a phone and accordingly hold it upright more often. As always, culture and experience matter here. Know your audience: the landscape option is especially welcomed by the younger set.