迅捷的iCloud：无法成功地使得无处不在的工作

Question

我的应用会生成我要复制到用户的iCloud Drive帐户的特定图像文件。

根据我的理解，对setUbiquitous（）的简单调用应该触发iCloud在设备之间同步文件，以便用户可以在Mac查找器上显示文件。

我的代码如下：

  class func write(image data: Data, to path: String) -> URL? {
        var path = "\(path).\(ext)"

        let fullPath = getDocumentsDirectory().appendingPathComponent(path)

        do {
            try data.write(to: fullPath, options: [.atomic])

            // Make it ubiquitous

                if var ubiquityUrl = FileManager.default.url(forUbiquityContainerIdentifier: nil) {
                    ubiquityUrl = ubiquityUrl.appendingPathComponent("Documents/\(path)")
                    setUbiquitous(localUrl: fullPath, ubiquityUrl: ubiquityUrl)
                    print("Setting ubiquitous at \(ubiquityUrl)")

                }
                else {
                    print("Unable to access iCloud Account")
                    print("Open the Settings app and enter your Apple ID into iCloud settings")
                }

            return fullPath
        }
        catch let error {
            print("write(image:to:): failed with error \(error) – bad permissions, bad filename, missing permissions, or more likely it can't be converted to the encoding")
            return nil
        }
    }

    class func setUbiquitous(localUrl: URL, ubiquityUrl: URL) {

        do {
            try FileManager.default.setUbiquitous(true, itemAt: localUrl, destinationURL: ubiquityUrl)
        } catch let error {
            print("*** error: setUbiquitous failed \(error.localizedDescription)")
        }
    }

不幸的是，到目前为止，我还没有成功实现这一目标。我有这个错误：

Setting ubiquitous at file:///private/var/mobile/Library/Mobile%20Documents/iCloud~com~***~Tree/Documents/3481-4.jpg
*** error: setUbiquitous failed The file “3481-4.jpg” couldn’t be saved in the folder “***Tree” because a file with the same name already exists.

我应该如何更新现有文件？

此外，我在iCloud管理设置应用程序中看不到任何文件，因为我的应用程序未列出（尽管在使用iCloud之前它已在笔中列出）。

旁注：

根据this，我在关键的NSUbiquitousContainers下的plist文件中添加了以下内容，但我不确定它扮演的角色或者它与我对iCloud的使用是否真的相关。

<dict>
    <key>com.***.Tree</key>
    <dict>
        <key>NSUbiquitousContainerIsDocumentScopePublic</key>
        <true/>
        <key>NSUbiquitousContainerSupportedFolderLevels</key>
        <string>Any</string>
        <key>NSUbiquitousContainerName</key>
        <string>AppleTree</string>
    </dict>
</dict>