让sdwebimage不缓存图片,每次都重新加载url

在AppDelegate didFinishLaunching的地方追加如下代码

SDWebImageDownloader *imgDownloader = SDWebImageManager.sharedManager.imageDownloader;
    imgDownloader.headersFilter  = ^NSDictionary *(NSURL *url, NSDictionary *headers) {
        
        NSFileManager *fm = [[NSFileManager alloc] init];
        NSString *imgKey = [SDWebImageManager.sharedManager cacheKeyForURL:url];
        NSString *imgPath = [SDWebImageManager.sharedManager.imageCache defaultCachePathForKey:imgKey];
        NSDictionary *fileAttr = [fm attributesOfItemAtPath:imgPath error:nil];
        
        NSMutableDictionary *mutableHeaders = [headers mutableCopy];
        
        NSDate *lastModifiedDate = nil;
        
        if (fileAttr.count > 0) {
            if (fileAttr.count > 0) {
                lastModifiedDate = (NSDate *)fileAttr[NSFileModificationDate];
            }
            
        }
        NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
        formatter.timeZone = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
        formatter.locale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US"];
        formatter.dateFormat = @"EEE, dd MMM yyyy HH:mm:ss z";
        
        NSString *lastModifiedStr = [formatter stringFromDate:lastModifiedDate];
        lastModifiedStr = lastModifiedStr.length > 0 ? lastModifiedStr : @"";
        [mutableHeaders setValue:lastModifiedStr forKey:@"If-Modified-Since"];
        
        return mutableHeaders;
    };

使用时,要使用 SDWebImageRefreshCached

[myCell.iconView3 sd_setImageWithURL:iconArray[2]
                            placeholderImage:[UIImage imageNamed:@"icon"]
                                     options:SDWebImageRefreshCached];