                 print(folderPath)
                 strongSelf._createFolderIfNeeded(folderPath)
                 
-                let filePath = folderPath.stringByAppendingPathComponent(strongSelf.archiveName)
+                let filePath = (folderPath as NSString).stringByAppendingPathComponent(strongSelf.archiveName)
                 
                 data.writeToFile(filePath, atomically: true)
                 if strongSelf.saveOperationQueue.operationCount == 1 {

            {
                let folderPath = strongSelf._folderPathFromFolderName(folderName, insideCacheFolder: true)

                let filePath = folderPath.stringByAppendingPathComponent(strongSelf.archiveName)
                let data = NSData(contentsOfFile: filePath)
                completion(data)
            }

    private func _deleteCache() {
        let folderName = name
        let folderPath = _folderPathFromFolderName(folderName, insideCacheFolder: true)
        let filePath = (folderPath as NSString).stringByAppendingPathComponent(archiveName)
        do {
            try NSFileManager.defaultManager().removeItemAtPath(filePath)
        }
