GIF转换成UIImage，以及UIImageView展示GIF

如何把GIF转换成UIImage
下列加载方法由SDWebImage中的sd_animatedGIFWithData:改写而成。由该方法我们可以用GIF的数据生成UIImage.
Objective-C版本：

#import "UIImage+GIF.h"
#import <ImageIO/ImageIO.h>

@implementation UIImage (GIF)

+ (UIImage *)animatedGIFImagesWithData:(NSData *)data {
    if (!data) {
        return nil;
    }
    
    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);
    
    size_t count = CGImageSourceGetCount(source);
    
    UIImage *staticImage;
    
    if (count <= 1) {
        staticImage = [[UIImage alloc] initWithData:data];
    } else {

        CGFloat scale = 1;
        scale = [UIScreen mainScreen].scale;
        
        NSMutableArray<UIImage *>* array = [[NSMutableArray alloc] initWithCapacity:count];
        for (int i = 0; i < count; i++) {
            CGImageRef CGImage = CGImageSourceCreateImageAtIndex(source, i, NULL);

            UIImage *frameImage = [UIImage imageWithCGImage:CGImage scale:scale orientation:UIImageOrientationUp];
            [array addObject:frameImage];

            CGImageRelease(CGImage);
        }
        
        staticImage = [UIImage animatedImageWithImages:array duration:0.0f];

    }
    
    CFRelease(source);
    
    return staticImage;
}

@end

Swift版本：

extension UIImage {
    
    class func animatedGIFImages(data: Data) -> UIImage? {
        if let source = CGImageSourceCreateWithData(data as CFData, nil) {
            let count = CGImageSourceGetCount(source)
            var staticImage: UIImage? = nil
            
            if (count <= 1) {
                staticImage = UIImage(data: data)
            } else {
                let scale = UIScreen.main.scale
                var array: [UIImage] = []
                
                for i in 1...count {
                    if let cgImage = CGImageSourceCreateImageAtIndex(source, i, nil) {
                       let frameImage = UIImage(cgImage: cgImage, scale: scale, orientation: .up)
                        array.append(frameImage)
                    } else {
                        continue
                    }
                }
                staticImage = UIImage.animatedImage(with: array, duration: 0)
            }
            return staticImage
        } else {
            return nil
        }
        
    }
}

在ViewController中设置:

@IBOutlet weak var imageView: UIImageView!

func setGIF() {
        let path = Bundle.main.path(forResource: "testGIF", ofType: ".gif")
        if let data = FileManager.default.contents(atPath: path!) {
            if let image = UIImage.animatedGIFImages(with: data) {
                if image.isGIF() { // image.images != nil
                    imageView.animationDuration = TimeInterval((image.images?.count ?? 0) / 10)
                    imageView.animationImages = image.images
                    imageView.startAnimating()
                }
            }
        }
    }