iOS/Swift 4:如何在不删除现有目标文件和文件夹的情况下，复制包含多个包含文件的文件夹？

import Foundation

func copyFolder(sourceURL: URL, destinationURL: URL) {
    let fileManager = FileManager.default
    
    do {
        try fileManager.createDirectory(at: destinationURL, withIntermediateDirectories: true, attributes: nil)
        
        let fileURLs = try fileManager.contentsOfDirectory(at: sourceURL, includingPropertiesForKeys: nil)
        
        for fileURL in fileURLs {
            let destinationFileURL = destinationURL.appendingPathComponent(fileURL.lastPathComponent)
            try fileManager.copyItem(at: fileURL, to: destinationFileURL)
        }
        
        print("Folder copied successfully.")
    } catch {
        print("Error while copying folder: \(error.localizedDescription)")
    }
}

// Example usage
let sourceURL = URL(fileURLWithPath: "/path/to/source/folder")
let destinationURL = URL(fileURLWithPath: "/path/to/destination/folder")

copyFolder(sourceURL: sourceURL, destinationURL: destinationURL)