Trying to update local json file - ios

Question

To start off, I want to say that I am new to using JSON, so if this code needs some cleanup also, let me know. So I am trying to update json file. I have created an empty jsonfile named data.json in my project, inside a folder I named Data. The file looks like this:
{
"fullname": "Testuser2",
"answered": 0,
"correct": 0
}
This is my JSONData.swift:
import Foundation
struct UserData: Codable {
let fullname: String
let answered: Int
let correct: Int
}
struct GlobalVariable{
static var fullname = String()
static var answered = Int()
static var correct = Int()
}
These function to read the json file:
private func readLocalFile(forName name: String) -> Data? {
do {
if let bundlePath = Bundle.main.path(forResource: name,
ofType: "json"),
let jsonData = try String(contentsOfFile: bundlePath).data(using: .utf8) {
return jsonData
}
} catch {
print(error)
}
return nil
}
private func parse(jsonData: Data) {
do {
let decodedData = try JSONDecoder().decode(UserData.self,
from: jsonData)
GlobalVariable.fullname = decodedData.fullname
GlobalVariable.answered = decodedData.answered
GlobalVariable.correct = decodedData.correct
} catch {
print("decode error")
}
}
And this is how I use it:
func getJSON() {
if let localData = self.readLocalFile(forName: "data") {
self.parse(jsonData: localData)
print(GlobalVariable.fullname)
print(GlobalVariable.answered)
print(GlobalVariable.correct)
}
}
So the getJSON successfully shows me the correct values.
Now after the GlobalVariable.answered and GlobalVariable.correct has been incrementet, I want to save it.
This is the code I am trying to use to save it:
func saveJSON {
print("---------")
print(GlobalVariable.fullname)
print(GlobalVariable.answered)
print(GlobalVariable.correct)
print("---------")
let dataToUpdate = [UserData(fullname: GlobalVariable.fullname, answered: GlobalVariable.answered, correct: GlobalVariable.correct)]
do {
let jsonData = try JSONEncoder().encode(dataToUpdate)
let jsonString = String(data: jsonData, encoding: .utf8)!
print(jsonString)
if let documentDirectory = FileManager.default.urls(for: .documentDirectory,
in: .userDomainMask).first {
let pathWithFilename = documentDirectory.appendingPathComponent("data.json")
do {
try jsonString.write(to: pathWithFilename,
atomically: true,
encoding: .utf8)
} catch {
// Handle error
}
}
} catch { print(error) }
}
The three print codes inside saveJSON shows the correct value, but someone nothing gets saved to the json file. The json file stays untouched.. How come?
I've also tried removing the .json from let pathWithFilename = documentDirectory.appendingPathComponent("data.json"), but still not working..

Answer 1

You are starting with your data.json in your bundle.
You read that, change the values, and then write it to Documents folder.
So, when you want to read the file, you need to first see if it exists in the Documents folder. If so, read it from there. If it doesn't exist (e.g. first time the app is run), then read it from the bundle.
Edit
The general idea is:
try to load the json file from the app's Documents folder
if that fails
create a "blank" user data object and show the Name Input view
if we successfully loaded the json file
use that data
after every change (name was entered, user answered a question), update the user data object and save (overwrite) the json file in the Documents folder
No need to have a .json file in your bundle, because you'll create a blank user data object if there is no .json file in the Documents folder.
Here is a complete example you can run and inspect:
struct UserData: Codable {
var fullname: String
var answered: Int
var correct: Int
}
class FileTestVC: UIViewController {
var userData: UserData!
let nameTextField = UITextField()
let nameLabel = UILabel()
let questionLabel = UILabel()
let resultNameLabel = UILabel()
let resultLabel = UILabel()
let userNameView = UIView()
let questionView = UIView()
let restartView = UIView()
let numQuestions: Int = 10
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .systemBackground
setupNameView()
setupQuestionView()
setupRestartView()
[userNameView, questionView, restartView].forEach { v in
v.translatesAutoresizingMaskIntoConstraints = false
v.backgroundColor = UIColor(white: 0.95, alpha: 1.0)
v.layer.cornerRadius = 16
v.layer.borderWidth = 2
v.isHidden = true
view.addSubview(v)
}
userNameView.layer.borderColor = UIColor.systemBlue.cgColor
questionView.layer.borderColor = UIColor.systemRed.cgColor
restartView.layer.borderColor = UIColor.systemGreen.cgColor
let g = view.safeAreaLayoutGuide
NSLayoutConstraint.activate([
userNameView.topAnchor.constraint(equalTo: g.topAnchor, constant: 40.0),
userNameView.centerXAnchor.constraint(equalTo: g.centerXAnchor),
questionView.topAnchor.constraint(equalTo: g.topAnchor, constant: 40.0),
questionView.centerXAnchor.constraint(equalTo: g.centerXAnchor),
restartView.topAnchor.constraint(equalTo: g.topAnchor, constant: 40.0),
restartView.centerXAnchor.constraint(equalTo: g.centerXAnchor),
])
userData = UserData(fullname: "", answered: 0, correct: 0)
if let jData = readLocalFile(forName: "data.json") {
do {
userData = try JSONDecoder().decode(UserData.self, from: jData)
} catch {
print(error)
}
}
if userData.fullname.isEmpty {
userNameView.isHidden = false
} else {
if userData.answered < numQuestions {
questionView.isHidden = false
nameLabel.text = userData.fullname
showNextQuestion()
} else {
showResult()
}
}
}
func setupNameView() {
// add a text field and "Save" button to userNameView
nameTextField.borderStyle = .roundedRect
let saveBtn = UIButton()
saveBtn.setTitle("Save", for: [])
saveBtn.setTitleColor(.white, for: .normal)
saveBtn.setTitleColor(.lightGray, for: .highlighted)
saveBtn.backgroundColor = .systemBlue
saveBtn.layer.cornerRadius = 8
[nameTextField, saveBtn].forEach { v in
v.translatesAutoresizingMaskIntoConstraints = false
userNameView.addSubview(v)
}
let g = userNameView
NSLayoutConstraint.activate([
nameTextField.topAnchor.constraint(equalTo: g.topAnchor, constant: 20.0),
nameTextField.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
nameTextField.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
nameTextField.widthAnchor.constraint(equalToConstant: 280.0),
saveBtn.topAnchor.constraint(equalTo: nameTextField.bottomAnchor, constant: 20.0),
saveBtn.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
saveBtn.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
saveBtn.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -20.0),
])
saveBtn.addTarget(self, action: #selector(saveNameTapped(_:)), for: .touchUpInside)
}
func setupQuestionView() {
// add labels + Right and Wrong buttons to questionView
nameLabel.textAlignment = .center
nameLabel.backgroundColor = .yellow
nameLabel.text = "Name"
questionLabel.textAlignment = .center
questionLabel.backgroundColor = .green
questionLabel.numberOfLines = 0
questionLabel.text = "Question"
let rightBtn = UIButton()
rightBtn.setTitle("Right", for: [])
rightBtn.setTitleColor(.white, for: .normal)
rightBtn.setTitleColor(.lightGray, for: .highlighted)
rightBtn.backgroundColor = .systemGreen
rightBtn.layer.cornerRadius = 8
let wrongBtn = UIButton()
wrongBtn.setTitle("Wrong", for: [])
wrongBtn.setTitleColor(.white, for: .normal)
wrongBtn.setTitleColor(.lightGray, for: .highlighted)
wrongBtn.backgroundColor = .systemRed
wrongBtn.layer.cornerRadius = 8
[nameLabel, questionLabel, rightBtn, wrongBtn].forEach { v in
v.translatesAutoresizingMaskIntoConstraints = false
questionView.addSubview(v)
}
let g = questionView
NSLayoutConstraint.activate([
nameLabel.topAnchor.constraint(equalTo: g.topAnchor, constant: 20.0),
nameLabel.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
nameLabel.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
questionLabel.topAnchor.constraint(equalTo: nameLabel.bottomAnchor, constant: 20.0),
questionLabel.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
questionLabel.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
questionLabel.widthAnchor.constraint(equalToConstant: 280.0),
rightBtn.topAnchor.constraint(equalTo: questionLabel.bottomAnchor, constant: 20.0),
rightBtn.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
wrongBtn.topAnchor.constraint(equalTo: questionLabel.bottomAnchor, constant: 20.0),
wrongBtn.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
wrongBtn.leadingAnchor.constraint(equalTo: rightBtn.trailingAnchor, constant: 20.0),
wrongBtn.widthAnchor.constraint(equalTo: rightBtn.widthAnchor),
wrongBtn.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -20.0),
])
rightBtn.addTarget(self, action: #selector(rightAnswerTapped(_:)), for: .touchUpInside)
wrongBtn.addTarget(self, action: #selector(wrongAnswerTapped(_:)), for: .touchUpInside)
}
func setupRestartView() {
// add labels + button to restartView
resultNameLabel.textAlignment = .center
resultNameLabel.backgroundColor = .yellow
resultNameLabel.text = "name"
resultLabel.textAlignment = .center
resultLabel.backgroundColor = .green
resultLabel.numberOfLines = 0
resultLabel.text = "You answered"
let restartBtn = UIButton()
restartBtn.setTitle("Restart", for: [])
restartBtn.setTitleColor(.white, for: .normal)
restartBtn.setTitleColor(.lightGray, for: .highlighted)
restartBtn.backgroundColor = .systemBlue
restartBtn.layer.cornerRadius = 8
[resultNameLabel, resultLabel, restartBtn].forEach { v in
v.translatesAutoresizingMaskIntoConstraints = false
restartView.addSubview(v)
}
let g = restartView
NSLayoutConstraint.activate([
resultNameLabel.topAnchor.constraint(equalTo: g.topAnchor, constant: 20.0),
resultNameLabel.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
resultNameLabel.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
resultLabel.topAnchor.constraint(equalTo: resultNameLabel.bottomAnchor, constant: 20.0),
resultLabel.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
resultLabel.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
resultLabel.widthAnchor.constraint(equalToConstant: 280.0),
restartBtn.topAnchor.constraint(equalTo: resultLabel.bottomAnchor, constant: 20.0),
restartBtn.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
restartBtn.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
restartBtn.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -20.0),
])
restartBtn.addTarget(self, action: #selector(restartTapped(_:)), for: .touchUpInside)
}
#objc func saveNameTapped(_ sender: Any?) {
guard let s = nameTextField.text,
!s.isEmpty
else { return }
view.endEditing(true)
userNameView.isHidden = true
questionView.isHidden = false
userData.fullname = s
nameLabel.text = userData.fullname
saveJSON(userData)
questionLabel.text = "Question \(userData.answered + 1) of \(numQuestions)\nAnswer Right or Wrong"
}
#objc func restartTapped(_ sender: Any?) {
// "empty" user data object
userData = UserData(fullname: "", answered: 0, correct: 0)
// save (overwrite) existing data
saveJSON(userData)
restartView.isHidden = true
nameTextField.text = ""
userNameView.isHidden = false
}
#objc func rightAnswerTapped(_ sender: Any?) {
userData.correct += 1
showNextQuestion()
}
#objc func wrongAnswerTapped(_ sender: Any?) {
showNextQuestion()
}
func showNextQuestion() {
userData.answered += 1
saveJSON(userData)
if userData.answered < numQuestions {
questionLabel.text = "Question \(userData.answered + 1) of \(numQuestions)\nAnswer Right or Wrong"
} else {
questionView.isHidden = true
showResult()
}
}
func showResult() {
restartView.isHidden = false
resultNameLabel.text = userData.fullname
resultLabel.text = "You answered \(userData.correct) Right!"
}
private func readLocalFile(forName name: String) -> Data? {
if let documentDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first {
let pathWithFilename = documentDirectory.appendingPathComponent(name)
do {
let jd = try String(contentsOf: pathWithFilename)
return jd.data(using: .utf8)
} catch {
print(error)
}
return nil
}
return nil
}
func saveJSON(_ d: UserData) {
do {
let jsonData = try JSONEncoder().encode(d)
let jsonString = String(data: jsonData, encoding: .utf8)!
if let documentDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first {
let pathWithFilename = documentDirectory.appendingPathComponent("data.json")
do {
try jsonString.write(to: pathWithFilename,
atomically: true,
encoding: .utf8)
} catch {
print(error)
}
}
} catch {
print(error)
}
}
}