Using UI to keep our user inside our application

With nearly half a million apps in the App Store, users have a good deal of choice, often downloading many applications and only using them for a brief period of time.

As developers, it is our goal to keep users inside our application for as long as possible. This is increasingly important if we rely upon advertising as a revenue model, as sponsors typically pay per impression and applications with longer impressions draw greater ad revenue.

Time spent inside our application is a key metric, and a number for which designers and developers wrestle with constantly, trying to keep users engaged for a few seconds longer with each visit. In many applications, this number is absolutely vital, with advertising money tied to the number of impressions displayed along with the length of each view.

But keeping the user inside our application is tough, especially with various marketing studies asserting that uses rarely open an application more than two...