Because the accordion view didn't allow enough room to display content, the team instead decided to use a horizontal slider at the top of the screen, a compact solution that left plenty of space for headlines. You swipe the slider left or right like a dial to see more content categories, tapping the topic you'd like to browse. The original Facebook app introduced this style of slider navigation and, although later versions of that app no longer use a slider, Facebook had already helped make the control familiar, if not quite a convention. For those who don't find the control immediately obvious, USA Today provides a subtle animation that hints at the control's use by showing its intended movement, a live demonstration that's repeated until people pick it up themselves.
Rusty: I get really excited about the small things, especially when we can find a way to demonstrate a new or non-standard user interaction without interfering or slowing down the users ability to use the app. With the horizontal section slider, we found that some users didn't understand that they could slide the bar to reveal additional sections. We originally thought that breaking the "Life" section so that it is partially obscured on the right edge of the screen would be enough to indicate to the user that more information would be revealed by sliding, but that wasn't always enough.
To help, we added an animation so that when a user launches the Headlines section of the app, the categories in the slider navigation bar slide into place from the left of the screen. It keeps doing this every time you visit that section until the user slides the bar for themselves. Once the user slides the bar for the first time, we stop doing the animation. We felt this was a good way to train users who were having trouble recognizing the control without having to add an annoying message or interfere with those users who already understood how the slider control worked.
Figure 3-34. Until users slide the navigation bar themselves for the first time, the app animates it at launch, sliding the bar in from the left to hint that it can move and nudging users to give it a try.
We do something similar when you first arrive at the Weather or Pictures screen. The section bars in the accordion view drop into place from the top of the screen. The movement suggests that you can do something with them, reinforcing that you can tap the accordion bars to reveal additional information.