Passing back data to first viewController

Question

I have a basic understanding of how to handle swift protocols to pass data between two viewcontrollers. My situation is this: I wanted to pass data back to my first viewcontroller.

For example:

First ViewController

class ViewControllerA: UIViewController, ViewControllerCResult {

    func set(data: String) {

    }

}

Second ViewController

class ViewControllerB: UIViewController {

}

Third ViewController

protocol ViewControllerCResult {
   set(data: String)
}

class ViewControllerC: UIViewController {
    var delegate: ViewControllerCResult?
}

ViewControllerA -> ViewControllerB -> ViewControllerC

I would like to pass data from ViewControllerC to ViewControllerA. Can anyone help me with this?

Are they linked? For instance, is B a child of A,and C a child of B? — Hack Saw, Jul 09 '18 at 03:17
Just add `var delegate: ViewControllerCResult?` to `ViewControllerB ` too, then `ViewControllerB ` add the same one to `ViewControllerC ` — Tj3n, Jul 09 '18 at 03:21
Could you write why you need to pass data to first controller? A & C should never communicate. It's violating law of demeter. — Aaina Jain, Jul 09 '18 at 03:26
Exactly @HackSaw , when I finish the task in C I perform a popViewController back to A, and wanted to return the result to A. — Thomas Marques, Jul 09 '18 at 03:32
Might be better if C and B were children of A, even if that means B asking A to show C. This reflects the idea that A is the master controller, and B and C are subcontrollers of it. Then it's simply passing data to the parent. — Hack Saw, Jul 09 '18 at 03:40
Possible duplicate of [Passing Data between View Controllers](https://stackoverflow.com/questions/5210535/passing-data-between-view-controllers) — Andreas Oetjen, Jul 09 '18 at 06:38
I understood how to do it @HackSaw . It worked. I created a function that receives the values and passed directly, since B and C are children of A. — Thomas Marques, Jul 09 '18 at 13:39
I also managed to do protocols according to the answer @ShauketSheikh — Thomas Marques, Jul 09 '18 at 13:39

Muhammad Shauket · Accepted Answer · 2018-07-10T02:45:15.473

You can pass Delegates from Controller A -> B -> C , and when popViewcontroller will be called you can check the self.delegate in ViewController C, if it exist just call function like this self.delegate?.set("data from c"). Check

popControllerPressed Function in ViewController3

First View controller

class ViewController: UIViewController, ViewControllerCResult {

var delegate: ViewControllerCResult?

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

@IBAction func pushControllerPressed(_ sender: Any) {
    if let viewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "ViewController2") as? ViewController2 {
        if let navigator = navigationController {
            viewController.delegate = self
            navigator.pushViewController(viewController, animated: true)
        }
    }
}

func set(data: String) {

}

}

Second ViewController

class ViewController2: UIViewController, ViewControllerCResult {

var delegate: ViewControllerCResult?

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

@IBAction func pushControllerPressed(_ sender: Any) {
    if let viewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "ViewController3") as? ViewController3 {
        if let navigator = navigationController {
            viewController.delegate = self.delegate
            navigator.pushViewController(viewController, animated: true)
        }
    }
}

func set(data: String) {
    print(data)
}

}

Third ViewController

protocol ViewControllerCResult {
   func set(data: String)
}

class ViewController3: UIViewController, ViewControllerCResult {

var delegate: ViewControllerCResult?

func set(data: String) {
    print(data)
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

@IBAction func popControllerPressed(_ sender: Any) {
    for controller in self.navigationController!.viewControllers as Array {
        if controller.isKind(of: ViewController.self) {
            delegate?.set(data: "data from C")
            self.navigationController!.popToViewController(controller, animated: true)
            break
        }
    }

}

}

Here is Code Link: Pass data forth and back

Passing back data to first viewController

1 Answers1