UIImage+GIF.swift SDWebImage中处理GIF的分类的swift版实现

//

//  UIImage+GIF.swift

//  swiftPractise

//

//  Created by 云君 on 2017/6/5.

//  Copyright © 2017年 pilgrim. All rights reserved.

//

import Foundation

import UIKit

import ImageIO

extension UIImage {

    class
func animatedGIFWith(data:
Data?) -> UIImage? {

        if
let data = data {

            if
let source = CGImageSourceCreateWithData(data
as CFData,
nil) {

                let count = CGImageSourceGetCount(source)

                var animatedImage:
UIImage? = nil

                if count <=
1 {

                    animatedImage = UIImage(data: data)

                } else {

                    var images: [UIImage] = []

                    var duration:
TimeInterval = 0.0

                    for i
in 0..<count {

                        let image = CGImageSourceCreateImageAtIndex(source, i,
nil)

                        if image ==
nil {

                            continue

                        }

                        duration = duration + frameDurationAt(index: i, source: source)

                        images.append(UIImage(cgImage: image!, scale: UIScreen.main.scale, orientation: .up))

                    }

                    if duration ==
0 {

                        duration = (1.0 /
10.0) * Double(count)

                    }

                    animatedImage = UIImage.animatedImage(with: images, duration: duration)

                }

                return animatedImage

            } else {

                return
nil

            }

        } else {

            return
nil

        }

    }

    class
func frameDurationAt(index:
Int, source: CGImageSource) ->
TimeInterval {

        var frameDuration:
TimeInterval = 0.1

        if
let cfFrameProperties = CGImageSourceCopyPropertiesAtIndex(source, index,
nil) {

            let frameProperties = cfFrameProperties
as NSDictionary

            if
let gifProperties = frameProperties[kCGImagePropertyGIFDictionary
as String]
as? NSDictionary {

                if
let delayTimeUnclampedProp = gifProperties[kCGImagePropertyGIFUnclampedDelayTime
as String]
as? NSNumber {

                    frameDuration = delayTimeUnclampedProp.doubleValue

                } else {

                    if
let delayTimeProp = gifProperties[kCGImagePropertyGIFDelayTime
as String]
as? NSNumber {

                        frameDuration = delayTimeProp.doubleValue

                    }

                }

            }

        }

        // Many annoying ads specify a 0 duration to make an image flash as quickly as possible.

        // We follow Firefox's behavior and use a duration of 100 ms for any frames that specify

        // a duration of <= 10 ms. See <rdar://problem/7689300> and <http://webkit.org/b/36082>

        // for more information.

        if frameDuration <
0.011 {

            frameDuration = 0.100

        }

        return frameDuration

    }

    class
func animatedGIF(name:
String) -> UIImage? {

        let scale = UIScreen.main.scale

        if scale >
1.0 {

            if
let retinaPath = Bundle.main.path(forResource: name.appending("@2x"), ofType:
"gif") {

                var data:
Data?

                do {

                    data = try Data(contentsOf: URL(fileURLWithPath: retinaPath))

                } catch {

                    print("从path获取图片data失败")

                }

                if
let data = data {

                    if
let image = UIImage.animatedGIFWith(data: data) {

                        return image

                    }

                }

            }

            if
let path = Bundle.main.path(forResource: name, ofType:
"gif") {

                var data:
Data?

                do {

                    data = try Data(contentsOf: URL(fileURLWithPath: path))

                } catch {

                    print("从path获取图片data失败")

                }

                if
let data = data {

                    if
let image = UIImage.animatedGIFWith(data: data) {

                        return image

                    }

                }

            }

            return UIImage(named: name)

        } else {

            if
let path = Bundle.main.path(forResource: name, ofType:
"gif") {

                var data:
Data?

                do {

                    data = try Data(contentsOf: URL(fileURLWithPath: path))

                } catch {

                    print("从path获取图片data失败")

                }

                if
let data = data {

                    if
let image = UIImage.animatedGIFWith(data: data) {

                        return image

                    }

                }

            }

            return UIImage(named: name)

        }

    }

    func animatedImageByScalingAndCroppingTo(size:
CGSize) -> UIImage? {

        if __CGSizeEqualToSize(self.size, size) || __CGSizeEqualToSize(size, .zero) {

            return
self

        }

        var scaledSize = size

        var thumbnailPoint = CGPoint.zero

        let widthFactor = size.width /
self.size.width

        let heightFactor = size.height /
self.size.height

        let scaleFactor = widthFactor > heightFactor ? widthFactor : heightFactor

        scaledSize.width = self.size.width * scaleFactor

        scaledSize.height = self.size.height * scaleFactor

        if widthFactor > heightFactor {

            thumbnailPoint.y = (size.height - scaledSize.height) *
0.5

        } else
if widthFactor < heightFactor {

            thumbnailPoint.x = (size.width - scaledSize.width) *
0.5

        }

        var scaledImages: [UIImage] = []

        if
let images = self.images {

            for image
in images {

                UIGraphicsBeginImageContextWithOptions(size,
false, 0.0)

                image.draw(in: CGRect(x: thumbnailPoint.x, y: thumbnailPoint.y, width: scaledSize.width, height: scaledSize.height))

                if
let newImage = UIGraphicsGetImageFromCurrentImageContext() {

                    scaledImages.append(newImage)

                }

                UIGraphicsEndImageContext()

            }

            return UIImage.animatedImage(with: scaledImages, duration:
self.duration)

        } else {

            return
nil

        }

    }

}