iOS 获取gif图片循环次数和时长

//获取gif图片的总时长和循环次数
- (NSTimeInterval)durationForGifData:(NSData *)data{ 
    //将GIF图片转换成对应的图片源
    CGImageSourceRef gifSource = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);
    //获取其中图片源个数，即由多少帧图片组成
    size_t frameCout = CGImageSourceGetCount(gifSource);
    //定义数组存储拆分出来的图片
    NSMutableArray* frames = [[NSMutableArray alloc] init];
    NSTimeInterval totalDuration = 0;
    for (size_t i=0; i<frameCout; i++) {
        //从GIF图片中取出源图片
        CGImageRef imageRef = CGImageSourceCreateImageAtIndex(gifSource, i, NULL);
        //将图片源转换成UIimageView能使用的图片源
        UIImage* imageName = [UIImage imageWithCGImage:imageRef];
        //将图片加入数组中
        [frames addObject:imageName];
        NSTimeInterval duration = [self gifImageDeleyTime:gifSource index:i];
        totalDuration += duration;
        CGImageRelease(imageRef);
    }

   //获取循环次数   
    NSInteger loopCount;//循环次数
    CFDictionaryRef properties = CGImageSourceCopyProperties(gifSource, NULL);
    if (properties) {
        CFDictionaryRef gif = CFDictionaryGetValue(properties, kCGImagePropertyGIFDictionary);
        if (gif) {
            CFTypeRef loop = CFDictionaryGetValue(gif, kCGImagePropertyGIFLoopCount);
            if (loop) {
         //如果loop == NULL，表示不循环播放，当loopCount  == 0时，表示无限循环；
           CFNumberGetValue(loop, kCFNumberNSIntegerType, &loopCount)
      };
        }
    }

    CFRelease(gifSource);
    return totalDuration;
}

 //获取GIF图片每帧的时长
- (NSTimeInterval)gifImageDeleyTime:(CGImageSourceRef)imageSource index:(NSInteger)index {
    NSTimeInterval duration = 0;
    CFDictionaryRef imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, index, NULL);
    if (imageProperties) {
        CFDictionaryRef gifProperties;
        BOOL result = CFDictionaryGetValueIfPresent(imageProperties, kCGImagePropertyGIFDictionary, (const void **)&gifProperties);
        if (result) {
            const void *durationValue;
            if (CFDictionaryGetValueIfPresent(gifProperties, kCGImagePropertyGIFUnclampedDelayTime, &durationValue)) {
                duration = [(__bridge NSNumber *)durationValue doubleValue];
                if (duration < 0) {
                    if (CFDictionaryGetValueIfPresent(gifProperties, kCGImagePropertyGIFDelayTime, &durationValue)) {
                        duration = [(__bridge NSNumber *)durationValue doubleValue];
                    }
                }
            }
        }
    }
    
    return duration;
}