delba/gifu

Highly performant animated GIF support for iOS in Swift

Adds performant animated GIF support to UIKit, without subclassing UIImageView. Check out the demo. If you're looking for the Japanese prefecture, click here.

Why?

Because Apple's +animatedImage* is not meant to be used for animated GIFs (loads all the frames in memory), and the few third party implementations that got it right (see Credits) still require you to use a UIImageView subclass, which is not very flexible and might clash with other application-specific functionality.

How?

Gifu is a UIImage subclass and UIImageView extension written in Swift. It uses CADisplayLink to animate the view and only keeps a limited number of frames in-memory, which exponentially minimizes memory usage for large GIF files (+300 frames).

The figure below summarizes how this works in practice. Given an image containing 10 frames, Gifu will load the current frame (red), pre-load the next two frames in this example (orange), and nullify all the other frames to free up memory (gray):

Usage

Use git submodules or drag-and-drop the files in your Xcode project. I can't believe I'm saying this in 2014.

Once done, you can call setAnimatableImage(named:) or setAnimatableImage(data:) on your UIImageView (or its subclass):

let imageView = UIImageView(...)

imageView.setAnimatableImage(named: "computer-kid.gif")
// imageView.setAnimatableImage(data: NSData(...))

The image view will not start animating until you call startAnimating() on it. You can stop the animation anytime using stopAnimating(), and resume it using startAnimating().

The isAnimating() method returns the current animation state of the view.

Demo App

For an example, check out the demo app here (requires Xcode 6).

Compatibility

• iOS 7+

Roadmap

The usual suspects:

• Add documentation.
• Write some basic tests.

Needless to say, you are welcome to contribute.

Credits

• The animation technique described above was originally spotted on OLImageView, then improved in YLGIFImage.

• The font used in the logo is Azuki

• Kudos to my colleague Tony DiPasquale for helping out with the factory methods.

• The characters used in the icon and example image in the demo are from Samurai Champloo.

License

See LICENSE.