问保存UIDocument失败，权限错误-“`NSCocoaErrorDomain`‘代码`513’

EN

class DocumentBrowserViewController: UIDocumentBrowserViewController, UIDocumentBrowserViewControllerDelegate {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        delegate = self
        
        allowsDocumentCreation = false
        allowsPickingMultipleItems = false
    }
    
    func documentBrowser(_ controller: UIDocumentBrowserViewController, didPickDocumentsAt documentURLs: [URL]) {
        guard let sourceURL = documentURLs.first else { return }
        
        if sourceURL.pathExtension == "csv" {
            
            // Create a CSV document so we can read the CSV data
            let csvDocument = CSVDocument(fileURL: sourceURL)
            csvDocument.open { _ in
                
                guard let csv = csvDocument.csvData else {
                    fatalError("CSV is nil upon open")
                }
                
                // Create the file at the same location as the csv, with the same name just a different extension
                var pivotURL = sourceURL.deletingLastPathComponent()
                let pivotFilename = sourceURL.lastPathComponent .replacingOccurrences(of: "csv", with: "pivot")
                pivotURL.appendPathComponent(pivotFilename, isDirectory: false)
                
                let model = PivotModel()
                model.csv = csv
                let document = PivotDocument(fileURL: pivotURL)
                document.model = model
                
                document.save(to: pivotURL, for: .forCreating, completionHandler: { success in
                    
                    // `success` is false here
                    
                    DispatchQueue.main.async {
                        self.performSegue(withIdentifier: "presentPivot", sender: self)
                    }
                })
            }
        }
    }
    
}

import SwiftCSV // This is pulled in using SPM and works as I expect, so is unlikely causing this problem 

class CSVDocument: UIDocument {
    
    var csvData: CSV?
    
    override func contents(forType typeName: String) throws -> Any {
        return Data()
    }
    
    override func load(fromContents contents: Any, ofType typeName: String?) throws {
        guard let data = contents as? Data else {
            fatalError("No file data")
        }
        
        guard let string = String(data: data, encoding: .utf8) else {
            fatalError("Cannot load data into string")
        }
        
        csvData = try CSV(string: string)
    }
}

class PivotDocument: UIDocument {
    
    var model: PivotModel!
    var url: URL!
    
    override func contents(forType typeName: String) throws -> Any {
        let encoder = JSONEncoder()
        return try encoder.encode(model)
    }
    
    override func load(fromContents contents: Any, ofType typeName: String?) throws {        
        guard let data = contents as? Data else {
            fatalError("File contents are not Data")
        }
        
        let decoder = JSONDecoder()
        model = try decoder.decode(PivotModel.self, from: data)
    }
    
    override func handleError(_ error: Error, userInteractionPermitted: Bool) {
        let theError = error as NSError
        
        print("\(theError.code)") // 513
        print("\(theError.domain)") // NSCocoaErrorDomain
        print("\(theError.localizedDescription)") // “example.pivot” couldn’t be moved because you don’t have permission to access “CSVs”.
        
        super.handleError(error, userInteractionPermitted: userInteractionPermitted)
    }
}