This line uses the `SDWebImage` library to asynchronously download the image, cache it (both in memory and on disk), and finally set the `UIImageView` image property. This library also supports placeholder images and notifying you of when the download completes. I highly recommend it.

Another alternative is `AFNetworking`, which can do the same thing and makes a whole bunch of basic networking very easy. The major advantage is that `SDWebImage` supports caching images on disk, which is nice.