         guard let siteURL = (url as NSURL).wmf_site, let imageName = WMFParseImageNameFromSourceURL(url) else {
             return nil
         }
-        return siteURL.absoluteString + "::" + imageName
+        return siteURL.absoluteString + "||" + imageName
     }
     
     fileprivate func variantForURL(_ url: URL) -> Int64 { // A return value of 0 indicates the original size

    }
    
    fileprivate func createCacheGroup(key: String, moc: NSManagedObjectContext) -> CacheGroup? {
        guard let group = NSEntityDescription.insertNewObject(forEntityName: "CacheGroup", into: moc) as? CacheGroup else {
            return nil
        }
        group.key = key
        return group
    }

    }
    
    fileprivate func permanentCacheFileURL(key: String, variant: Int64) -> URL {
        return self.permanentStorageDirectory.appendingPathComponent("\(key)||\(variant)", isDirectory: false)
    }
    
    fileprivate func fetchCacheItem(key: String, variant: Int64, moc: NSManagedObjectContext) -> CacheItem? {
