iOS中播放gif动态图的方式探讨 原

//要引入ImageIO库
#import <ImageIO/ImageIO.h>

//解析gif文件数据的方法 block中会将解析的数据传递出来
-(void)getGifImageWithUrk:(NSURL *)url
               returnData:(void(^)(NSArray<UIImage *> * imageArray,
                                NSArray<NSNumber *>*timeArray,
                                CGFloat totalTime,
                                NSArray<NSNumber *>* widths,
                                NSArray<NSNumber *>* heights))dataBlock{
    //通过文件的url来将gif文件读取为图片数据引用
    CGImageSourceRef source = CGImageSourceCreateWithURL((CFURLRef)url, NULL);
    //获取gif文件中图片的个数
    size_t count = CGImageSourceGetCount(source);
    //定义一个变量记录gif播放一轮的时间
    float allTime=0;
    //存放所有图片
    NSMutableArray * imageArray = [[NSMutableArray alloc]init];
    //存放每一帧播放的时间
    NSMutableArray * timeArray = [[NSMutableArray alloc]init];
    //存放每张图片的宽度 （一般在一个gif文件中，所有图片尺寸都会一样）
    NSMutableArray * widthArray = [[NSMutableArray alloc]init];
    //存放每张图片的高度
    NSMutableArray * heightArray = [[NSMutableArray alloc]init];
    //遍历
    for (size_t i=0; i<count; i++) {
        CGImageRef image = CGImageSourceCreateImageAtIndex(source, i, NULL);
        [imageArray addObject:(__bridge UIImage *)(image)];
        CGImageRelease(image);
        //获取图片信息
        NSDictionary * info = (__bridge NSDictionary*)CGImageSourceCopyPropertiesAtIndex(source, i, NULL);
        CGFloat width = [[info objectForKey:(__bridge NSString *)kCGImagePropertyPixelWidth] floatValue];
        CGFloat height = [[info objectForKey:(__bridge NSString *)kCGImagePropertyPixelHeight] floatValue];
        [widthArray addObject:[NSNumber numberWithFloat:width]];
        [heightArray addObject:[NSNumber numberWithFloat:height]];
        NSDictionary * timeDic = [info objectForKey:(__bridge NSString *)kCGImagePropertyGIFDictionary];
        CGFloat time = [[timeDic objectForKey:(__bridge NSString *)kCGImagePropertyGIFDelayTime]floatValue];
        allTime+=time;
        [timeArray addObject:[NSNumber numberWithFloat:time]];
        CFRelease(info);
    }
    CFRelease(source);
    dataBlock(imageArray,timeArray,allTime,widthArray,heightArray);
}

-(void)yh_setImage:(NSURL *)imageUrl{
        __weak id __self = self;
        [self getGifImageWithUrk:imageUrl returnData:^(NSArray<UIImage *> *imageArray, NSArray<NSNumber *> *timeArray, CGFloat totalTime, NSArray<NSNumber *> *widths, NSArray<NSNumber *> *heights) {
            //添加帧动画
            CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"contents"];
            NSMutableArray * times = [[NSMutableArray alloc]init];
            float currentTime = 0;
            //设置每一帧的时间占比
            for (int i=0; i<imageArray.count; i++) {
                [times addObject:[NSNumber numberWithFloat:currentTime/totalTime]];
                currentTime+=[timeArray[i] floatValue];
            }
            [animation setKeyTimes:times];
            [animation setValues:imageArray];
            [animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]];
            //设置循环
            animation.repeatCount= MAXFLOAT;
            //设置播放总时长
            animation.duration = totalTime;
            //Layer层添加
            [[(UIImageView *)__self layer]addAnimation:animation forKey:@"gifAnimation"];
        }];
}

    UIImageView * imageView = [[UIImageView alloc]initWithFrame:CGRectMake(0,0 , 320, 200)];
    NSURL * url = [[NSURL alloc]initFileURLWithPath:[[NSBundle mainBundle] pathForResource:imageName ofType:nil]];
    [imageView yh_setImage:url];
    [self.view addSubview:imageView];

         //读取gif数据
         NSData *gifData = [NSData dataWithContentsOfURL:imageUrl];
        UIWebView *webView = [[UIWebView alloc] initWithFrame:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
        //取消回弹效果
        webView.scrollView.bounces=NO;
        webView.backgroundColor = [UIColor clearColor];
        //设置缩放模式
        webView.scalesPageToFit = YES;
        //用webView加载数据
        [webView loadData:gifData MIMEType:@"image/gif" textEncodingName:nil baseURL:nil];