How can I change the filename in a SwiftUI Document-based app? - swiftui

Question

I've been using the new template for a document-based SwiftUI app. While you get a lot of file-management "for free" in the new template, as it stands in the iOS version users have to back out of the file to the file browser to change the filename. I want to create an opportunity for the user to rename the file while it is open.
Here's a sample project focused on the issue: https://github.com/stevepvc/DocumentRenamer
In the code, I've added to the template code a simple UI with a textfield for the user to enter a new name. When the user hits the "rename" button, the app checks to see if the URL with that name component is available, appending a suffix if necessary to create a target url.
func getTargetURL() -> URL {
let baseURL = self.fileurl.deletingLastPathComponent()
print("filename: \(self.filename)")
print("fileURL: \(self.fileurl)")
print("BaseURL: \(baseURL)")
var target = URL(fileURLWithPath: baseURL.path + "/\(filename).exampletext")
var nameSuffix = 1
while (target as NSURL).checkPromisedItemIsReachableAndReturnError(nil) {
target = URL(fileURLWithPath: baseURL.path + "/\(filename)-\(nameSuffix).sermon")
print("Checking: \(target)")
nameSuffix += 1
}
print("Available Target: \(target)")
return target
}
It then attempts to rename the file, and this is when I am stuck. I have tried several methods, most recently the following:
func changeFilename(){
let target = getTargetURL()
var rv = URLResourceValues()
let newFileName = target.deletingPathExtension().lastPathComponent
rv.name = newFileName
do {
if fileurl.startAccessingSecurityScopedResource(){
try fileurl.setResourceValues(rv)
fileurl.stopAccessingSecurityScopedResource()
}
} catch {
print("Error:\(error)")
}
}
But I keep getting the following error:
Domain=NSCocoaErrorDomain Code=513 "You don’t have permission to save the file “Untitled” in the folder “DocumentRenamer”."
I have also tried this without the startAccessingSecurityScopedResource() check, and alternatively have tried creating a helper class as follows:
class FileMover: NSObject {
func moveFile(originalURL: URL, updatedURL:URL) -> Bool {
let coordinator = NSFileCoordinator(filePresenter: nil)
var writingError: NSError? = nil
var success : Bool = true
print("moving file")
coordinator.coordinate(writingItemAt: originalURL, options: NSFileCoordinator.WritingOptions.forMoving, error: &writingError, byAccessor: { (coordinatedURL) in
do {
try FileManager.default.moveItem(at: coordinatedURL, to: updatedURL)
success = true
print("file moved")
} catch {
print(error)
success = false
}
})
return success
}
}
But using this method locks up the app entirely. It's possible that there is something about iCloud permissions going on there, but I think I've have those set up appropriately.
It appears to work fine in the simulator, but not when run on a device.
What is the correct method for renaming a file in the app's container?