インスタっぽい画像表示をつくりたいと思って実装。
CircleProgressView(https://github.com/CardinalNow/iOS-CircleProgressView)とお馴染みSDWebImage(https://github.com/rs/SDWebImage)を使用。

        //メンバ変数をnilにしておく
        self.entriesImage.image = nil;
        SDWebImageManager *imageManager = [SDWebImageManager sharedManager];
        [imageManager.imageCache queryDiskCacheForKey:self.entryModel.image_url done:^(UIImage *image, SDImageCacheType cacheType)
        {
            if (image) {
                NSLog(@"キャッシュがある");
                self.circleProgressView.hidden = YES;
                //取得したimageをメンバ変数へ代入
                self.entriesImage.image = image; 
            } else {
                //キャッシュがないのでネットワークから読み出すなどの処理をする
                [[SDWebImageDownloader sharedDownloader] downloadImageWithURL:[NSURL URLWithString:self.entryModel.image_url]
                                                                      options:0
                                                                     progress:
                 ^(NSInteger receivedSize, NSInteger expectedSize) {
                     self.circleProgressView.hidden = NO;
                     float progress = [@(receivedSize) floatValue]/[@(expectedSize) floatValue];

                     self.circleProgressView.progress = progress;
                 } completed:^(UIImage *image, NSData *data, NSError *error, BOOL finished) {
                     if( error ){
                         return;
                     }
                     
                     if (finished){
                         SDImageCache *imageCache = [[SDWebImageManager sharedManager]imageCache];
                         [imageCache storeImage:image forKey:self.entryModel.image_url];
                         
                         self.circleProgressView.hidden = YES;
                         self.entriesImage.image = image;
                     }
                     
                 }];
            }
        }];

◼︎参考
http://hack.aipo.com/archives/9983/
http://blogios.stack3.net/archives/288
https://xn--t8j4aa4npge9cynpab8kvj.jp/
http://blog.waft.me/ios-http-cache/
https://www.xn--t8j4c7dcf6169bud5f.jp/