如果您已经有文件的URL，请以文件URL取代'newFile'。'vc'是目前的ViewController
请注意，asCopy = false将移动文档，asCopy = true将复制文档。当asCopy = false时，似乎有bug in iOS 16+禁用了“移动”按钮。错误在后续版本FB11627056中得到修复

//Present Document Picker
let controller = UIDocumentPickerViewController(forExporting: [newFile], asCopy: false)
vc.present(controller, animated: true) {
    //this will be called as soon as the picker is launched NOT after save
}

你有没有按照苹果提供的here的说明去做？我在这里总结一下重要的部分：
用户点击“完成”后，系统将调用代理的documentPicker（_：didPickDocumentsAt：）方法，并为用户的选定目录传递一组安全范围的URL ....当用户在文档选取器中选择一个目录时，系统将授予您的应用访问该目录及其所有内容的权限。
所以首先，你需要实现委托方法，这样你就知道用户选择了什么。具体来说，documentPicker(_:didPickDocumentsAt:)是很重要的一个，尽管你也会想监听“cancel”。然后你需要访问这个作用域资源并写入它。
下面是我从上面链接的文档中截取的一个例子。这个例子只从目录中 * 读取 *，但是你也可以用同样的方式写入它。

func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentAt url: URL) {
    // Start accessing a security-scoped resource.
    guard url.startAccessingSecurityScopedResource() else {
        // Handle the failure here.
        return
    }

    // Make sure you release the security-scoped resource when you finish.
    defer { url.stopAccessingSecurityScopedResource() }

    // Use file coordination for reading and writing any of the URL’s content.
    var error: NSError? = nil
    NSFileCoordinator().coordinate(readingItemAt: url, error: &error) { (url) in
            
        let keys : [URLResourceKey] = [.nameKey, .isDirectoryKey]
            
        // Get an enumerator for the directory's content.
        guard let fileList =
            FileManager.default.enumerator(at: url, includingPropertiesForKeys: keys) else {
            Swift.debugPrint("*** Unable to access the contents of \(url.path) ***\n")
            return
        }
            
        for case let file as URL in fileList {
            // Start accessing the content's security-scoped URL.
            guard url.startAccessingSecurityScopedResource() else {
                // Handle the failure here.
                continue
            }

            // Do something with the file here.
            Swift.debugPrint("chosen file: \(file.lastPathComponent)")
                
            // Make sure you release the security-scoped resource when you finish.
            url.stopAccessingSecurityScopedResource()
        }
    }
}