Swift UIDocument saving unreliable

Question

Why is calling .save on an external (iCloud) UIDocument so tricky? :frowning: It either:

1. takes forever and doesn't save, or
2. save operation fails, despite of calling startAccessingSecurityScopedResource() prior to the save call.
3. saves sometimes, randomly!

So unsure about what am I missing here. Here's my code for the saving bit (I am only dealing with plain text files):

private func saveDocument() {
        if (document == nil) { return }

        saveLabel.text = "Saving.."
        saveLabel.isHidden = false
        saveIndicator.isHidden = false
        saveIndicator.startAnimating()
        if (!(document?.fileURL.startAccessingSecurityScopedResource() ?? false)) {
            self.saveLabel.text = "File is busy!"
            self.saveIndicator.stopAnimating()
            self.saveIndicator.isHidden = true
            Common.alert(view: self, message: "File is busy! Please try again in a bit.")
            self.showRetrySaveButton()
            return
        }

        document?.save(to: fileURL!,
                           for: .forOverwriting,
               completionHandler: {(success: Bool) -> Void in

                self.saveIndicator.stopAnimating()
                self.saveIndicator.isHidden = true
            if success {
                self.document?.fileURL.stopAccessingSecurityScopedResource()
                self.saveLabel.text = "Saved!"
                self.hideSaved()
                self.hideDoneButton()
                
            } else {
                self.saveIndicator.isHidden = true
                self.saveLabel.text = "Save failed!"
                Common.alert(view: self, message: "File save failed! Please try again.")
                self.showRetrySaveButton()
            }
        })
    }

The text box that I use for saving keeps the text loaded even after the save operation, which is why I don't really close the UIDocument (do I really need to close the document before say, opening the same document again or opening another one?). I only save the changes when the editing is finished or done button is pressed.

Help is much appreciated!