I have learned Swift and Xcode for about 3 weeks and I am doing an Todo App just for practice. But when I was trying to add new item to my todo list the error occurred saying that "Unexpectedly found nil while unwrapping an Optional value".
I have the main screen which is created by Main.storyboard and an add button on the main screen. When click that button it goes to a new ViewController which I created via the Eureka framework, user can enter some information like title, description, category in that form and pass them back to the main screen. I used the delegate protocol for passing data, when I click the Save Item button the app crashed and it said that
"Fatal error: Unexpectedly found nil while unwrapping an Optional value".
The code is below:
import Foundation
import Eureka
protocol CanReceive {
func dataReceived(data: ToDo)
}
class AddItemViewController : FormViewController {
var delegate : CanReceive?
var todoItem : ToDo?
static let dateFormatter: DateFormatter = {
let formatter = DateFormatter()
formatter.dateFormat = "MMM d yyyy, h:mm a"
return formatter
}()
override func viewDidLoad() {
super.viewDidLoad()
form +++ Section()
<<< TextRow(){
$0.title = "Title"
$0.placeholder = "Enter text here"
$0.onChange { [unowned self] row in
self.todoItem?.title = row.value
}
}
<<< TextRow(){
$0.title = "Description"
$0.placeholder = "Give some description"
$0.onChange { [unowned self] row in
self.todoItem?.description = row.value
}
}
<<< AlertRow<String>() {
$0.title = "Category"
$0.selectorTitle = "Select the category"
$0.options = ["Personal 😄", "Home 🏠", "Work 💼", "Play 🎮", "Health 🏋🏻♀️" , "Other"]
$0.onChange { [unowned self] row in
self.todoItem?.category = row.value
}
}
+++ Section(){ section in
section.header = {
var header = HeaderFooterView<UIView>(.callback({
let button = UIButton(frame: CGRect(x: 100, y: 100, width: 50, height: 50))
button.backgroundColor = .darkGray
button.setTitle("Save Item", for: .normal)
button.addTarget(self, action: #selector(self.buttonAction), for: .touchUpInside)
return button
}))
header.height = { 50 }
return header
}()
}
}
@objc func buttonAction(sender: UIButton!) {
delegate?.dataReceived(data: todoItem!)
self.dismiss(animated: true, completion: nil)
print("Button tapped")
}
}
The Todo type is defined as:
struct ToDo {
var title: String?
var description: String?
var category : String?
}
And here is the ViewController that controls the main.storyboard :
import UIKit
let storyBoard : UIStoryboard = UIStoryboard(name: "Main", bundle:nil)
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, CanReceive {
var todoList = [ToDo]()
let cellId = "CellId"
let test = ["Row1", "Row2", "Row3"]
let imageName = ["anchor", "arrow-down", "aperture"]
@IBOutlet weak var ImageTop: UIImageView!
@IBOutlet weak var tableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
self.tableView.register(UINib(nibName: "CustomTableViewCell", bundle: nil), forCellReuseIdentifier: cellId)
configureTableView()
ImageTop.image = UIImage(named: "todo-background")
}
//data source method
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return todoList.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as! CustomTableViewCell
cell.categoryLabel?.text = todoList[indexPath.row].category
cell.descriptionLabel.text = todoList[indexPath.row].description
var imageCategory = ""
switch todoList[indexPath.row].category {
case "Personal 😄":
imageCategory = "Personal"
case "Home 🏠":
imageCategory = "Home"
case "Work 💼":
imageCategory = "Work"
case "Play 🎮":
imageCategory = "Play"
case "Health 🏋🏻♀️":
imageCategory = "Health"
case "Other":
imageCategory = "Other"
default:
break
}
cell.imageCategory?.image = UIImage(named: imageCategory)
return cell
}
func configureTableView() {
self.tableView.rowHeight = 80
self.tableView.separatorStyle = .none
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
print("Did select row at index \(indexPath.row)")
print("Row height is: \(tableView.rowHeight)")
}
@IBAction func addButtonPressed(_ sender: RoundButton) {
let addItemViewController = AddItemViewController()
addItemViewController.delegate = self
self.present(addItemViewController, animated:true, completion:nil)
}
//Delegate
func dataReceived(data: ToDo) {
todoList.append(data)
return
}
}
Thank you for your time and sorry if my question is so silly.
The error occurs because in AddItemViewController the property todoItem is declared but not initialized.
I recommend to use temporary variables for the three properties and create a ToDo instance when the button is pressed
class AddItemViewController : FormViewController {
var delegate : CanReceive?
var title, description, category : String?
static let dateFormatter: DateFormatter = {
let formatter = DateFormatter()
formatter.dateFormat = "MMM d yyyy, h:mm a"
return formatter
}()
override func viewDidLoad() {
super.viewDidLoad()
form +++ Section()
<<< TextRow(){
$0.title = "Title"
$0.placeholder = "Enter text here"
$0.onChange { [unowned self] row in
self.title = row.value
}
}
<<< TextRow(){
$0.title = "Description"
$0.placeholder = "Give some description"
$0.onChange { [unowned self] row in
self.description = row.value
}
}
<<< AlertRow<String>() {
$0.title = "Category"
$0.selectorTitle = "Select the category"
$0.options = ["Personal 😄", "Home 🏠", "Work 💼", "Play 🎮", "Health 🏋🏻♀️" , "Other"]
$0.onChange { [unowned self] row in
self.category = row.value
}
}
+++ Section(){ section in
section.header = {
var header = HeaderFooterView<UIView>(.callback({
let button = UIButton(frame: CGRect(x: 100, y: 100, width: 50, height: 50))
button.backgroundColor = .darkGray
button.setTitle("Save Item", for: .normal)
button.addTarget(self, action: #selector(self.buttonAction), for: .touchUpInside)
return button
}))
header.height = { 50 }
return header
}()
}
}
@objc func buttonAction(sender: UIButton) { // no implicit unwrapped optional
let todoItem = ToDo(title: title, description: description, category : category)
delegate?.dataReceived(data: todoItem)
self.dismiss(animated: true, completion: nil)
print("Button tapped")
}
}