How to use protocol and delegate in my class? - ios

Question

I am using two view Controllers i.e. StateListVC and PlayVC. In StateListVC, I am using container view with 3 VCs. After tapping on 3rd View Controller, I am going to PlayVC with delegate method. I don't know how to do that. Please help me to resolve this issue.
StateListVC
class StateListVC: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewWillAppear(_ animated: Bool) {
if isMoveToAnotherVC
{
let vc = self.storyboard?.instantiateViewController(withIdentifier: "PlaceVC") as! PlaceVC
vc.delegate = self
}
}
}
extension StateListVC: MoveToAnotherVC {
func moving(string: String) {
print(string)
}
}
ThirdVC
protocol MoveToAnotherVC {
func moving(string: String)
}
class PlaceVC: UIViewController {
#IBOutlet weak var tableViewPlace: UITableView!
var delegate: MoveToAnotherVC? = nil
var arrPlace = ["Place1", "Place2"]
override func viewDidLoad() {
super.viewDidLoad()
}
extension PlaceVC: UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return arrPlace.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
cell.textLabel?.text = arrPlace[indexPath.row]
return cell
}
}
extension PlaceVC: UITableViewDelegate {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath)
{
isMoveToAnotherVC = true
print(delegate)
guard let delegate = self.delegate else{
print("Delegate not set")
return
}
delegate.moving(string: "test")
}
}

Answer 1

This is hooked up fine:
protocol MoveToAnotherVC: AnyObject {
func moving(string: String)
}
class StateListVC: UIViewController, MoveToAnotherVC {
override func viewDidLoad() {
super.viewDidLoad()
let vc = self.storyboard?.instantiateViewController(withIdentifier: "PlaceVC") as! PlaceVC
vc.delegate = self
}
func moving(string: String) {
print(string)
}
}
class PlaceVC: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var tableViewPlace: UITableView!
weak var delegate: MoveToAnotherVC?
var arrPlace = ["Place1", "Place2"]
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return arrPlace.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
cell.textLabel?.text = arrPlace[indexPath.row]
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
delegate?.moving(string: "test")
}
}
I made the protocol a class protocol, moved the view controller instantiation into viewDidLoad, removed some (what I consider) extraneous unwrapping, and stripped your protocol/delegate pattern down to the basics. This works. I would plug this into your project and add what you need piece by piece until it breaks because your problem is outside of this. I suspect it may have to do with something you didn't include in your question but this answers your question about how to set up a protocol/delegate pattern.