Pass String Variable Data from one Class/ViewController to Class/ViewController - ios

Question

I have two viewControllers:
1. CheckoutVC
2. DeliveryTimeVC
In DeliveryTimeVC I have the following variable:
class DeliveryTimeVC: UIViewController {
var tableViewDay:String = ""
}
I use the following push to go from CheckoutVC to DeliveryTimeVC:
let storyboard = UIStoryboard(name: Storyboard.DeliveryTimeStoryboard, bundle: nil)
let controller = storyboard.instantiateViewController(withIdentifier: StoryboardId.DeliveryTimeVC)
navigationController?.pushViewController(controller, animated: true)
In DeliveryTimeVC I have a tableView where on didSelect I go back to CheckoutVC and in didSelect func I have the following code to append my variable before leaving the controller:
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableViewDay.removeAll()
tableViewDay.append(cell.weekDayLbl.text!)
navigationController?.popViewController(animated: true)
}
How can I transfer the String variable data from DeliveryTimeVC to another variable in CheckoutVC? Lets say I create a variable in CheckoutVC as:
class CheckoutVC: UIViewController, CartProductCellDelegate {
var tableViewDayTransferedData:String = ""
}
How can I transfer the data from tableViewDay:String to tableViewDayTransferedData:String

Answer 1

well you can use this lines
let storyboard = UIStoryboard(name: "NAMEOFYOURSTORYBOARD", bundle: nil)
let vc = storyboard.instantiateViewController(withIdentifier: "IDOFYOURVIEW") as! CheckoutVC
vc.tableViewDayTransferedData = self. tableViewDay
self.navigationController!.pushViewController(vc, animated: true)

Answer 2

Based on #Hassan Shahbazi comment above I was able to change his code slightly and get the final answer that works for me:
protocol DeliveryTimeDelegate: class {
func didGetData(tableViewDayTransferedData: String)
}
class DeliveryTimeVC: UIViewController {
weak var delegate: DeliveryTimeDelegate?
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableViewDay.removeAll()
tableViewDay.append(cell.weekDayLbl.text!)
delegate?.didGetData(tableViewDayTransferedData: tableViewDay)
navigationController?.popViewController(animated: true)
}
}
class CheckoutVC: UIViewController, DeliveryTimeDelegate {
func ...() {
let storyboard = UIStoryboard(name: Storyboard.DeliveryTimeStoryboard, bundle: nil)
let controller = storyboard.instantiateViewController(withIdentifier: StoryboardId.DeliveryTimeVC) as! DeliveryTimeVC
controller.delegate = self
navigationController?.pushViewController(controller, animated: true)
}
func didGetData(tableViewDayTransferedData: String) {
tableViewDayTransferedData = tableViewDayTransferedData
}
}
in the last func you see two same variables; they just have the same name: tableViewDayTransferedData = tableViewDayTransferedData first one is from CheckoutVC. the second one is from the protocol.

Answer 3

There are generally 2 main patterns for data/variable passing in iOS.
Delegate Pattern
The popular pattern for Objective-c days, but still useful and easy to do. You'll need to define a delegate protocol and use it for passing variables.
protocol DeliveryTimeDelegate: class {
func didGetData(tableViewDay: String)
}
class DeliveryTimeVC: UIViewController {
weak var delegate: DeliveryTimeDelegate?
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableViewDay.removeAll()
tableViewDay.append(cell.weekDayLbl.text!)
delegate?.didGetData(tableViewDay: "YOUR_VALUE")
navigationController?.popViewController(animated: true)
}
}
class CheckoutVC: UIViewController, CartProductCellDelegate {
func ...() {
let storyboard = UIStoryboard(name: Storyboard.DeliveryTimeStoryboard, bundle: nil)
let controller = storyboard.instantiateViewController(withIdentifier: StoryboardId.DeliveryTimeVC)
controller.delegate = self
navigationController?.pushViewController(controller, animated: true)
}
}
extension CheckoutVC: DeliveryTimeDelegate {
func didGetData(tableViewDay: String) {
tableViewDayTransferedData = tableViewDay
}
}
Closure Pattern
The pattern could be seen as the swift friendly implementation of delegate. It's important to pay enough attention to memory management and retain cycle issues when you're using closure.
class DeliveryTimeVC: UIViewController {
var onDataTransfered: ((String) -> Void)?
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableViewDay.removeAll()
tableViewDay.append(cell.weekDayLbl.text!)
self.onDataTransfered?("YOUR_VALUE")
navigationController?.popViewController(animated: true)
}
}
class CheckoutVC: UIViewController, DeliveryTimeDelegate {
func ...() {
let storyboard = UIStoryboard(name: Storyboard.DeliveryTimeStoryboard, bundle: nil)
let controller = storyboard.instantiateViewController(withIdentifier: StoryboardId.DeliveryTimeVC)
controller.onDataTransfered = { [weak self] tableViewDayTransferedData in
self?.tableViewDay = tableViewDayTransferedData
}
navigationController?.pushViewController(controller, animated: true)
}
}