Use of undeclared type 'TrailViewController' - trying to handle item details from list in iOS app - ios

Question

Another issue with learning.
I found this in Apple Dev documentation: THIS
My target is to handle one tap on my list of items. When I click I need to open edit window and handle which row I selected. I trying to put that solution into my code but I have no idea what is TrailViewController (I getting Chinese links at first Google search page). So I decided to put my code there. I getting error:
Use of undeclared type 'TrailViewController'.
They appear after I adding this into my code:
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let selectedTrail = elements[indexPath.row]
if let viewController = storyboard?.instantiateViewController(identifier: "TrailViewController") as? TrailViewController {
viewController.trail = selectedTrail
navigationController?.pushViewController(viewController, animated: true)
}
}
Full code from file below:
import UIKit
import Firebase
import FirebaseFirestore
class MainViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet weak var listOfItemsTableView: UITableView!
var elements: [Element] = []
override func viewDidLoad() {
super.viewDidLoad()
let db = Firestore.firestore()
db.collection("recipes").whereField("uid", isEqualTo: Auth.auth().currentUser!.uid).addSnapshotListener({ (snapshot, error) in
if let snapshot = snapshot {
var elementsTemp = [Element]()
for doc in snapshot.documents {
if let itemName = doc.get("name") as? String {
elementsTemp.append(Element(name: itemName))
}
}
self.elements = elementsTemp
self.listOfItemsTableView.reloadData()
} else {
if let error = error {
print(error)
}
}
})
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.listOfItemsTableView.reloadData()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return elements.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "elementCell", for: indexPath) as! ElementCell
cell.elementNameLabel.text = elements[indexPath.row].name
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let selectedTrail = elements[indexPath.row]
if let viewController = storyboard?.instantiateViewController(identifier: "TrailViewController") as? TrailViewController {
viewController.trail = selectedTrail
navigationController?.pushViewController(viewController, animated: true)
}
}
#IBAction func addItemButtonClicked(_ sender: Any) {
self.performSegue(withIdentifier: "toAddItemView", sender: self)
}
}
class Element {
var name = ""
convenience init(name: String) {
self.init()
self.name = name
}
}
Update 1
Ok, I made some progress, but at this moment I can't navigate to EditItemViewController. This is how my code looks now:
import UIKit
import Firebase
import FirebaseFirestore
class MainViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet weak var listOfItemsTableView: UITableView!
var elements: [Element] = []
var element: Element?
override func viewDidLoad() {
super.viewDidLoad()
let db = Firestore.firestore()
db.collection("recipes").whereField("uid", isEqualTo: Auth.auth().currentUser!.uid).addSnapshotListener({ (snapshot, error) in
if let snapshot = snapshot {
var elementsTemp = [Element]()
for doc in snapshot.documents {
if let itemName = doc.get("name") as? String {
elementsTemp.append(Element(name: itemName))
}
}
self.elements = elementsTemp
self.listOfItemsTableView.reloadData()
} else {
if let error = error {
print(error)
}
}
})
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.listOfItemsTableView.reloadData()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return elements.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "elementCell", for: indexPath) as! ElementCell
cell.elementNameLabel.text = elements[indexPath.row].name
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let selectedElement = elements[indexPath.row]
if let viewController = storyboard?.instantiateViewController(identifier: "EditItemViewControllerID") as? MainViewController {
viewController.element = selectedElement
self.navigationController?.pushViewController(viewController, animated: true)
}
}
#IBAction func addItemButtonClicked(_ sender: Any) {
self.performSegue(withIdentifier: "toAddItemView", sender: self)
}
}
class Element {
var name = ""
convenience init(name: String) {
self.init()
self.name = name
}
}
And how my storyboard looks at this moment:
Maybe I missed something?

Answer 1

Make a UIViewController named TrailViewController and add it as the class for a new UIViewController in your storyboard and you'll no longer get this error:
class TrailViewController: UIViewController {
var trail: Element?
// ...
}
Note: Also, don't forget to add the identifier for the new TrailViewController added in the storyboard as "TrailViewController" to get the UIViewController when calling instantiateViewController(identifier: in didSelectRow and perform navigation successfully.