Importing a GPX file results in an error that the text encoding of its contents can’t be determined-CodePudding

I'm letting users import a GPX file through the following method:

let documentPickerController = UIDocumentPickerViewController(documentTypes: ["public.item"], in: .import)
documentPickerController.allowsMultipleSelection = false
documentPickerController.delegate = self
self.present(documentPickerController, animated: true, completion: nil)

And parsing the selected file as following:

func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL]) {
    let firstFileURL = urls[0]
    var outputFileURL: URL? = nil

    let coordinator = NSFileCoordinator()
    var error: NSError? = nil
    coordinator.coordinate(readingItemAt: firstFileURL, options: [], error: &error) { (externalFileURL) -> Void in
        var tempURL = URL(fileURLWithPath: NSTemporaryDirectory())
        tempURL.appendPathComponent(externalFileURL.lastPathComponent)
        
        do {
            if FileManager.default.fileExists(atPath: tempURL.path) {
                try FileManager.default.removeItem(atPath: tempURL.path)
            }
            
            try FileManager.default.copyItem(atPath: externalFileURL.path, toPath: tempURL.path)
            outputFileURL = tempURL
        } catch {
            print("File operation error: "   error.localizedDescription)
        }
    }
    
    navigationController?.dismiss(animated: true, completion: nil)

    guard let path = outputFileURL?.path else { return }
    
    do {
        let content = try String(contentsOfFile: path) // error here
        let data = content.data(using: .utf8)
        let parser = XMLParser.init(data: data!)
    } catch {
        print(error)
    }
}

But, I'm getting the following error message:

couldn’t be opened because the text encoding of its contents can’t be determined.

I thought maybe it was the way I was importing the files so I tried changing public.item to following:

let types = UTType.types(tag: "gpx", tagClass: UTTagClass.filenameExtension, conformingTo: nil)
let documentPickerController = UIDocumentPickerViewController(documentTypes: types, in: .import)
documentPickerController.allowsMultipleSelection = false
documentPickerController.delegate = self
self.present(documentPickerController, animated: true, completion: nil)

and modifying the info.plist as explained in this article.

But then, none of the GPX files become selectable and turn grey from within the document picker.

CodePudding user response：

You're absolutely right. This expression is just wrong:

String(contentsOfFile: path)

You could specify the encoding by adding an encoding: parameter.

https://developer.apple.com/documentation/swift/string/init(contentsoffile:encoding:)

But don't. Don't use String(contentsOfFile:) at all. Don't use file paths at all. Use file URLs. Given a file URL, read from it with String(contentsOf:encoding:).

https://developer.apple.com/documentation/swift/string/init(contentsof:encoding:)