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.

To use Shimmer, create a FBShimmeringView or FBShimmeringLayer and add your content. To start shimmering, set the shimmering property to YES.

An example of making a label shimmer:

FBShimmeringView *shimmeringView = [[FBShimmeringView alloc] initWithFrame:self.view.bounds];
[self.view addSubview:shimmeringView];

UILabel *loadingLabel = [[UILabel alloc] initWithFrame:shimmeringView.bounds];
loadingLabel.textAlignment = NSTextAlignmentCenter;
loadingLabel.text = NSLocalizedString(@"Shimmer", nil);
shimmeringView.contentView = loadingLabel;

// Start shimmering.
shimmeringView.shimmering = YES;

There's also an example project. In the example, you can swipe horizontally and vertically to try various shimmering parameters, or tap to start or stop shimmering. (To build the example locally, you'll need to open FBShimmering.xcworkpace rather than the .xcodeproj.)

There are two options:

1. Shimmer is available as Shimmer in Cocoapods.
2. Manually add the files into your Xcode project. Slightly simpler, but updates are also manual.

Shimmer requires iOS 6 or later.

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.

See the CONTRIBUTING file for how to help out.

Shimmer is BSD-licensed. We also provide an additional patent grant.