Shimmer is an easy way to add a shimmering effect to any view in your app. It's useful as an unobtrusive loading indicator.
Shimmer was originally developed to show loading status in Paper.
Shimmer uses the -[CALayer mask] property to enable shimmering, similar to what's described in John Harper's 2009 WWDC talk (unfortunately no longer online). Shimmer uses CoreAnimation's timing features to smoothly transition "on-beat" when starting and stopping the shimmer.