The iPhone App

This page of the Playlister case study describes the iPhone application itself.

The Playlister Web Service has already taken care of all the resource-intensive work, so the Playlister iPhone application only has to receive the song data and put it on the screen.

Song data arrives at the iPhone in a lightweight format called JSON. All the application has to do is take each piece of song data from that JSON format and stick it into the appropriate iPhone UI element. This low overhead makes the application interface nice and snappy.

There is one part of the song detail view that has the potential to slow things down: the album cover art. A 100px by 100px album cover might weigh 16KB, which will load over EDGE in about 3 seconds. If I had to wait three seconds between tapping a song in the playlist and seeing the details, I would get impatient. But there is a solution for this slowdown. The iPhone SDK allows me to move the album art request to a separate processing thread. This means the song detail will load immediately when I tap a playlist entry, while the iPhone works on loading the album cover in the background. So my user experience stays snappy.

The diagram below shows the simple mapping between JSON data and iPhone UI elements. It also indicates the hyperlinked buttons that take you to destinations outside of the Playlister application.

And that's it!

Now I have a iPhone app that satisfies my general use case and all my specific requirements.

Thanks for reading the case study.