How to Read Data from Text File iOS 15 [duplicate]

Question

Update: This code works in the simulator, but not on my device. Obviously, I'm needing it to work on both.

I've followed the tutorials, yet I cannot seem to get this feature to work. When the user selects the barButtonItem, DocumentPicker opens allowing the user to select a .txt file. I then take the URL to the selected file and attempt to return a string from it; however, I'm getting the following error: "The file “Test.txt” couldn’t be opened because you don’t have permission to view it." What am I missing? Did I fail to ask for permission somewhere? I've tried cleaning the build folder - didn't work.

@IBAction func importFileBtnTapped(_ sender: Any) {
        selectFiles()
    }
    
    
    func selectFiles() {
        let types = UTType.types(tag: "txt",
                                 tagClass: UTTagClass.filenameExtension,
                                 conformingTo: nil)
        let documentPickerController = UIDocumentPickerViewController(forOpeningContentTypes: types)
        documentPickerController.delegate = self
        self.present(documentPickerController, animated: true, completion: nil)
    }
    
    
    func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL]) {
        guard let myURL = urls.first else {
            let alert = SCLAlertView()
            alert.showError("ERROR", subTitle: "Unable to retrieve document.")
            return
        }
        let text = createStringFromSelectedFile(fileURL: myURL)
        if text == "error" {
            print("ERROR creating a string from the selected file.")
            return
        }
        let separatedStrings = decipherString(text: text)
        if separatedStrings.first == "error" {
            print("ERROR deciphering the string in ClaimInfoViewController")
            return
        }
        for string in separatedStrings {
            print("\(string)")
        }
        print("import result: \(myURL)")
    }
    
    
    func documentPickerWasCancelled(_ controller: UIDocumentPickerViewController) {
        dismiss(animated: true, completion: nil)
    }
    
    
    func createStringFromSelectedFile(fileURL: URL) -> String {
        var text = String()
        do {
            text = try String(contentsOf: fileURL)
        }
        catch {
            print("ERROR in the createStringFromSelectedFile function in ClaimInfoViewController")
            print("The error: \(error.localizedDescription)")
            let alert = SCLAlertView()
            alert.showError("ERROR", subTitle: "Unable to read the file. Please try again.")
            return "error"
        }
        return text
    }
    
    func decipherString(text: String) -> [String]{
        let newText = text
        let startIndexes = ["<Claim#",
                            "<File#",
                            "<DateOfLoss:"
        ]
        var claimNumber = String()
        var fileNumber = String()
        var dateOfLoss = String()
        
        for indexValue in startIndexes {
            guard let index = newText.firstIndex(of: ">") else { return ["error"] }
            let newString = String(newText[..<index])
            
            if indexValue == "<Claim#" {
                claimNumber = newString
            }
            else if indexValue == "<File#" {
                fileNumber = newString
            }
            else if indexValue == "<DateOfLoss:" {
                dateOfLoss = newString
            }
        }
        
        let finalText = [claimNumber, fileNumber, dateOfLoss]
        
        return finalText
    }

@matt, thanks for your speedy reply. Would you be willing to post an answer showing me how I could implement the things mentioned at the link above? I don't mean to be an inconvenience, I'm just new and don't understand. Also, update: I tried my current project on a simulator, instead of my physical device, and it works. I'm not sure why it works for a simulator but not my device. — Christian W
– Christian W, Commented Mar 1, 2022 at 3:40

Christian W · Accepted Answer · 2022-03-01 03:51:56Z

0

Thanks to matt, who commented above, I was able to find out that it's a security issue. Adding this simple code resolved the issue:

let shouldStopAccessing = pickedFolderURL.startAccessingSecurityScopedResource()
        defer {
          if shouldStopAccessing {
            pickedFolderURL.stopAccessingSecurityScopedResource()
          }
       }

I added it right before this line of code that can be seen above:

let text = createStringFromSelectedFile(fileURL: myURL)

I got this code from here: StackOverflow Post

answered Mar 1, 2022 at 3:51

Christian W

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