contentsOfDirectory返回三个文件，枚举器返回none

Question

谁能看到我在这里做错了什么？ everything有三个文件，enumerator没有，第一个.nextObject退出：

    let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
    let everything = try! FileManager.default.contentsOfDirectory(at: documentsURL, includingPropertiesForKeys: nil, options: [])
    let keys = [URLResourceKey.isRegularFileKey, URLResourceKey.localizedNameKey]
    let options: FileManager.DirectoryEnumerationOptions = [.skipsPackageDescendants, .skipsSubdirectoryDescendants, .skipsHiddenFiles]
    let enumerator = FileManager.default.enumerator(
        at: documentsURL,
        includingPropertiesForKeys: keys,
        options: options,
        errorHandler: {(url, error) -> Bool in
            return true
    })
    if enumerator != nil {
        while let fileURL = enumerator!.nextObject() {
            // ...
        }
    }