Pass data between childViewControllers Swift - ios

Question

I put a container inside my MainViewController. Then added FirstViewController inside that container
let containerView = UIView()
view.addSubview(containerView)
let controller = FirstViewController()
addChildViewController(controller)
containerView.addSubview(controller.view)
controller.didMove(toParentViewController: self)
There are a UITextField and a UIButton inside FirstViewController. There is a label inside SecondViewController and var passedText = "" to update the UILabel text. I just want to set the UILabel text according to the UITextField text from FirstViewController when I press UIButton and it should leads to SecondViewController as well. This is the UIButton action method from FirstViewController. I'm not using Storyboard
#IBAction func btnPressed(_ sender: Any) {
let secondVC = SecondViewController()
addChildViewController(secondVC)
view.addSubview(secondVC.view)
secondVC.view.frame = view.bounds
secondVC.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
secondVC.didMove(toParentViewController: self)
secondVC.passedText = inputTextField.text!
}
This is FirstViewController
class FirstViewController: UIViewController {
#IBOutlet weak var inputTextField: UITextField!
let secondVC = SecondViewController()
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func btnPressed(_ sender: Any) {
addChildViewController(secondVC)
view.addSubview(secondVC.view)
secondVC.view.frame = view.bounds
secondVC.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
secondVC.didMove(toParentViewController: self)
secondVC.passedText = inputTextField.text!
}
}
This is SecondViewController
class SecondViewController: UIViewController {
var passedText = ""
#IBOutlet weak var label: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
label.text = passedText
}
}

Answer 1

Closure
class ParentViewController: UIViewController {
var embeddedViewController: UIViewController?
override func viewDidLoad() {
super.viewDidLoad()
let firstViewController = FirstViewController()
embedViewController(firstViewController)
firstViewController.passDataClosure = { [weak self] text in
let secondViewController = SecondViewController()
self?.embedViewController(secondViewController)
secondViewController.passedText = text
}
}
func embedViewController(_ viewController: UIViewController) {
removeEmbedded()
viewController.view.autoresizingMask = [.flexibleHeight, .flexibleWidth]
addChildViewController(viewController)
view.addSubview(viewController.view)
viewController.didMove(toParentViewController: self)
embeddedViewController = viewController
}
func removeEmbedded() {
embeddedViewController?.view.removeFromSuperview()
embeddedViewController?.didMove(toParentViewController: nil)
embeddedViewController?.removeFromParentViewController()
}
}
-
class FirstViewController: UIViewController {
var passDataClosure: ((String?) -> Void)?
#IBOutlet weak var inputTextField: UITextField!
#IBAction func btnPressed(_ sender: Any) {
passDataClosure?(inputTextField.text)
}
}
-
class SecondViewController: UIViewController {
var passedText: String? {
didSet {
label.text = passedText
}
}
#IBOutlet weak var label: UILabel!
}
Delegate
class ParentViewController: UIViewController, FirstViewControllerDelegate {
var embeddedViewController: UIViewController?
override func viewDidLoad() {
super.viewDidLoad()
let firstViewController = FirstViewController()
embedViewController(firstViewController)
firstViewController.delegate = self
}
func embedViewController(_ viewController: UIViewController) {
removeEmbedded()
viewController.view.autoresizingMask = [.flexibleHeight, .flexibleWidth]
addChildViewController(viewController)
view.addSubview(viewController.view)
viewController.didMove(toParentViewController: self)
embeddedViewController = viewController
}
func removeEmbedded() {
embeddedViewController?.view.removeFromSuperview()
embeddedViewController?.didMove(toParentViewController: nil)
embeddedViewController?.removeFromParentViewController()
}
// MARK: FirstViewControllerDelegate
func firstViewController(_ firstViewController: FirstViewController, pass text: String?) {
let secondViewController = SecondViewController()
embedViewController(secondViewController)
secondViewController.passedText = text
}
}
-
class SecondViewController: UIViewController {
var passedText: String? {
didSet {
label.text = passedText
}
}
#IBOutlet weak var label: UILabel!
}
-
protocol FirstViewControllerDelegate: class {
func firstViewController(_ firstViewController: FirstViewController, pass text: String?)
}
class FirstViewController: UIViewController {
weak var delegate: FirstViewControllerDelegate?
#IBOutlet weak var inputTextField: UITextField!
#IBAction func btnPressed(_ sender: Any) {
delegate?.firstViewController(self, pass: inputTextField.text)
}
}

Answer 2

As far as I can see, this should work:
secondVC.label.text = inputTextField.text
You currently have secondVC.label = inputTextField.text which shouldn't even compile.

Answer 3

you can create a singleton class for your scenario. so that you can access all of your important data from anywhere either from your firstViewController or SecondViewController.
class YourDataClass : NSObject{
var textFieldData = String()
var lblSeconddata = String()
struct Static
{
public static var instance: YourDataClass?
}
class var singleton: YourDataClass
{
if Static.instance == nil
{
Static.instance = YourDataClass()
}
return Static.instance!
}
}
now somewhere in your controller
YourDataClass.Singleton.textFieldData = txtFld.Text
YourDataClass.Singleton. lblSeconddata = lblText.Text
in smame way you can get it anywhere