76 lines
2.7 KiB
Markdown
76 lines
2.7 KiB
Markdown
<img src="https://db.tt/mZ1iMNXO" width="100" />
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Adds performant animated GIF support to UIKit, without subclassing `UIImageView`. If you're looking for the Japanese prefecture, click [here](https://goo.gl/maps/CCeAc).
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#### Why?
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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](#credits)) still require you to use a `UIImageView` subclass, which is not very flexible and might clash with other application-specific functionality.
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#### How?
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Gifu is a `UIImage` subclass and `UIImageView` extension written in Swift.
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It uses `CADisplayLink` to animate the view and only keeps a limited number of
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frames in-memory, which exponentially minimizes memory usage for large GIF files (+300
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frames).
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The figure below summarizes how this works in practice. Given an image
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containing 10 frames, Gifu will load the current frame (red), pre-load the next two frames in this example (orange),
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and nullify all the other frames to free up memory (gray):
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<img src="https://db.tt/ZLfx23hg" width="300" />
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#### Usage
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Use git submodules or drag-and-drop the files in your Xcode project. I can't
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believe I'm saying this in 2014.
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Once done, you can call `setAnimatableImage(named:)` or
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`setAnimatableImage(data:)` on your `UIImageView` (or its subclass):
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```swift
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let imageView = UIImageView(...)
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imageView.setAnimatableImage(named: "computer-kid.gif")
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// imageView.setAnimatableImage(data: NSData(...))
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```
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The image view will not start animating until you call `startAnimatingGIF()`
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on it. You can stop the animation anytime using `stopAnimatingGIF()`, and resume
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it using `startAnimatingGIF()`. These methods will fallback to UIKit's `startAnimating()` and `stopAnimating()`
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if the image view has no animatable image.
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Likewise, the `isAnimatingGIF()` method returns the current animation state of the view if it has an animatable image,
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or UIKit's `isAnimating()` otherwise.
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#### Demo App
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<img src="https://db.tt/ZoUNLHGp" width="300" />
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#### Compatibility
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- iOS 7+
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#### Roadmap
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The usual suspects:
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- Add documentation.
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- Write some basic tests.
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Needless to say, you are welcome to contribute.
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#### Credits
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- The animation technique described above was originally spotted on
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[OLImageView](https://github.com/ondalabs/OLImageView), then improved in [YLGIFImage](https://github.com/liyong03/YLGIFImage).
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- The font used in the logo is [Azuki](http://www.myfonts.com/fonts/bluevinyl/azuki/)
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- Kudos to my colleague [Tony DiPasquale](https://github.com/tonyd256) for helping out with the factory methods.
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- The characters used in the icon and example image in the demo are from [Samurai Champloo](https://en.wikipedia.org/wiki/Samurai_Champloo).
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#### License
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See LICENSE.
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