swift如何从我们在文档目录中创建的子文件夹中获取所有文件？

import Foundation

func getAllFilesInSubfolder() -> [URL]? {
    let fileManager = FileManager.default
    let documentsURL = fileManager.urls(for: .documentDirectory, in: .userDomainMask).first!
    let subfolderURL = documentsURL.appendingPathComponent("子文件夹名称")
    
    do {
        let fileURLs = try fileManager.contentsOfDirectory(at: subfolderURL, includingPropertiesForKeys: nil)
        return fileURLs
    } catch {
        print("获取文件失败：\(error)")
        return nil
    }
}

// 调用函数获取所有文件
if let files = getAllFilesInSubfolder() {
    for fileURL in files {
        print(fileURL.lastPathComponent)
    }
}