An asset friendly GIF library.

EasyGIF.swift

//
//  EasyGIF.swift
//
//  Created by Rocky Wei on 2019-06-06.
//  Copyright © 2019 Treefrog. All rights reserved.
//

import UIKit

/// An Easy GIF animation class
/// usage:
/// - load a GIF from asset:
/// ```
/// let gif = EasyGIF(named: "myGIF")
/// ```
/// - using the first frame as a static image:
/// ```
/// myImageView.image = gif.image
/// ```
/// - applying an one-time animation:
/// ```
/// gif.renderAnimation(onImageView: myView)
/// ```
public class EasyGIF {
	private var frames: [UIImage] = []

	/// load a GIF file from current asset by name
	/// - parameter named: name of the gif in the current asset
	public init?(named: String) {
		guard let asset = NSDataAsset(name: named) else { return nil }
		guard let source = CGImageSourceCreateWithData(asset.data as CFData, nil) else { return nil }
		for i in 0 ..< CGImageSourceGetCount(source) {
			if let frame = CGImageSourceCreateImageAtIndex(source, i, nil) {
				let image = UIImage(cgImage: frame)
				frames.append(image)
			}
		}
	}

	/// get the first frame as a static image
	public var image: UIImage? {
		return frames.first
	}

	/// directly access all the frames
	public var images: [UIImage] {
		return frames
	}

	/// perform animation on an image view
	/// - parameter onImageView: the image view to render
	/// - parameter duration: duration of the animation
	/// - parameter repeatCount: repeatCount of the naimation
	public func renderAnimation(onImageView imageView: UIImageView, duration: TimeInterval = 1, repeatCount: Int = 1) {
		imageView.animationImages = images
		imageView.animationDuration = duration
		imageView.animationRepeatCount = repeatCount
		imageView.startAnimating()
	}
}