SDWebImage 的使用

imageView 首选缓存 加载image
使用缓存

 [self.leftImageView sd_setImageWithURL:[NSURL URLWithString:model.imgUrl] placeholderImage:[UIImage imageNamed:@"placehold11"] completed:^(UIImage * _Nullable image, NSError * _Nullable error, SDImageCacheType cacheType, NSURL * _Nullable imageURL) {            if (image) {                UIImage *nowImgae=[YXTool imageByScalingAndCroppingForSize:CGSizeMake(90, 90) image:image];                self.leftImageView.image=nowImgae;            }else{                self.leftImageView.image=[YXTool imageByScalingAndCroppingForSize:CGSizeMake(90, 90) image:[UIImage imageNamed:@"placehold11"]];                //self.image_url.contentMode            }        }];

这种每次都会下载， 下载下来加载image

SDWebImageManager *manager = [SDWebImageManager sharedManager];        [manager.imageDownloader downloadImageWithURL:[NSURL URLWithString:model.imgUrl ] options:0        progress:^(NSInteger receivedSize, NSInteger expectedSize, NSURL * _Nullable targetURL) {        } completed:^(UIImage * _Nullable image, NSData * _Nullable data, NSError * _Nullable error, BOOL finished) {            if (image) {                UIImage *nowImgae=[YXTool imageByScalingAndCroppingForSize:CGSizeMake(90, 90) image:image];                self.leftImageView.image=nowImgae;            }else{                self.leftImageView.image=[YXTool imageByScalingAndCroppingForSize:CGSizeMake(90, 90) image:[UIImage imageNamed:@"placehold11"]];                //self.image_url.contentMode            }        }];