Programming the iPhone User Experience

Memory Lapse

Network-aware applications, such as RSS readers or clients for sites like Twitter and Digg, inherently depend on an Internet connection. Without web access, the data they display is off-limits.

The first time users launch such an application, they probably expect a load operation of some sort, preferably with a progress indicator to show that the application is doing something in the background. Notice should be given not only that a download is in progress, but also whether or not the download is successful. In most cases, a successful operation will simply display the downloaded data. Failures can be communicated with an icon, as in Twinkle, or with passive messaging, as in Shovel.

Figure 9-15 shows the first launch and network sync for the TED application. The translucent overlay and status indicator tell the user that the application is actively communicating with the TED web services, while the underlying screen gives a preview of the type of content. This approach is preferable to that taken by many applications that fail to store information when applications close, requiring users to have a network connection to continue reading content they have already downloaded at least once.

Figure 9-15. The first launch and network sync for the TED application

After the first successful download, user expectations change. Users expect that applications will store downloaded ...