4. Design accessibly. It's common to see young designers use small text and tight layouts that are hard for older users to read and accurately tap. Avoid the Retina effect: Just because there are now smaller pixels that make text technically readable at even smaller sizes, if you're much past the age of 35, human eyes still can't read such minuscule text. Use adaptive design instead, such as preferences over text size that adjust the layout accordingly. The new text-size API in iOS 7should reduce the burden of that coding for iPhones and iPads.
5. When showing mockups and prototypes to clients or users, do it on the device the app will run on. A PDF or Photoshop mockup on a large computer screen simply doesn't reflect the look and feel of a smartphone or tablet, nor are the interactions (such as touch, swipe, and type) the same. What looks and works right on a big screen with mouse and keyboard may feel horrible on a mobile device's small touchscreen. Likewise, what works well on a mobile device may function poorly on a computer screen, causing users and client to reject good options. Show your comps and protoypes in the actual context.
6. Beware metaphors. There are fewer universal graphical metaphors you can count on people understanding — the old analog images (TV screens, radio controls, tape players, cameras, filmstrips, LPs, rotary dial, pilot lights, and even CDs) are not operationally familiar to younger generations, even if they may have seen them in an older movie. Although iconography thoretically allows for more universal design, many of the analog bases for the icons are becoming less and less familiar, confusing users. The use of text may be better, even if localization is required — Apple's apparent conclusion, judging by iOS 7.
7. Beware oversimplification, where everything (color, weight, texture, and so on) looks the same. Too simple is as confusing as too complex, as both lead to difficulty in centering user focus for the task or content at hand.
8. Design apps, not applications. The more complex an app, the harder it is to use and navigate, especially in the smartphone context of on-the-go, uncertain environment (where users could be standing, sitting, or jostling, as well as working in dim light or bright light). If you have a lot of functionality to provide, consider breaking it into a set of related apps, each focused on a core functionality. This "don't overload the app" notion can be tough to explain to clients, especially given the pressure to "do more" in each revision, but it's essential that apps don't become unwieldy or confusingly complex. (Griffith suggests you cite the line "Freedom of choice is what you get, freedom from choice is what you want" from the band Devo's iconic "Freedom of Choice" song.)
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