update value of text when click back on navigation controller

Question

I have 2 controllers

and have got 1 global variable, the problem is if I go to controller 2 and click on button northAmericaClick, it will navigate back to control 1, but the value of global variable won't change!

this is my code

controller 1

class OurViewController: UIViewController {

    @IBOutlet weak var menuButton: UIBarButtonItem!

    @IBOutlet weak var selectedServer: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        selectedServer.setTitle(selected server, forState: UIControlState.Normal) // selected server this is global variable

}

controller 2

class selectServerController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

    }


    @IBAction func northAmericaClick(sender: AnyObject) {
        selectedserver = "North America"

                self.navigationController?.popViewControllerAnimated(true)
    }

If you want to set data in your parent view controller then probably you have to use unwind segue and not self.navigationController?.popViewControllerAnimated(true) — PK20
– PK20, Commented Nov 27, 2015 at 8:58
i know how to use segue , but this is help me because there's more than 1 input and if he go to other controller with segue the inputs will get empty — Mohammed Awad
– Mohammed Awad, Commented Nov 27, 2015 at 9:12

Community · Accepted Answer · 2017-05-23 12:16:09Z

2

From

You need to use a delegate. Here is an example how do use a delegate in Swift.

On your first ViewController, set your delegate when you load the second VC:

For example, if you are using the Storyboard Editor:

var secondViewController = (segue.destinationViewController.visibleViewController as  MySecondViewControllerClass)
secondViewController.delegate = self

Write a Protocol and define a func to write you values back

For example, create a file called "Protocol.swift" and write something like that:

protocol writeValueBackDelegate {
    func writeValueBack(value: String)
}

Add the function to your FirstViewController

func writeValueBack(value: String) {
   // this is my value from my second View Controller
}

And to your ViewControllerClass

class ViewController: UIViewController, writeValueBackDelegate

Go to the Second View Controller, and add the delegate here:

class SecondViewController: ViewController {

    // delegate for FirstViewController
    var delegate: writeValueBackDelegate?

On your Second View Controller, you can now use this to call the func in the first View Controller an pass data.

delegate?.writeValueBack("That is a value")

You also need to indicate that your first view controller implements the protocol: class ViewController: UIViewController, writeValueBackDelegate {

edited May 23, 2017 at 12:16

CommunityBot

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answered Nov 27, 2015 at 9:11

Viraj Padsala

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3 Comments

Mohammed Awad Over a year ago

this is in my second controller link ,, and this is my first controller link, when i click on select server it would go the second and show the images you it's like buttons each one got function if i click on it , it have to change the value of global variable , i don't think i need protocol to do that , but thanks :)

Oleh Kudinov Over a year ago

Personally I would do it with delegate. But you also have another option. Create a Model/Data class (singleton) for you view controllers and define the variable in it. Then access to this singleton from these view controllers. stackoverflow.com/questions/26742138/singleton-in-swift

Viraj Padsala Over a year ago

Use NSUserDefault as last option.

Oleh Kudinov · Accepted Answer · 2015-11-27 13:46:48Z

0

A part of doing it with delegate you also can create singleton class ViewControllersDataModel class and share the variable using it:

import Foundation

class ViewControllersDataModel {
    static let sharedInstance = ViewControllersDataModel()

    var selectedserver: String = ""

    private init() {
    }
}

And call it like this:

ViewControllersDataModel.sharedInstance.selectedserver = "Selected Option";

edited Nov 27, 2015 at 13:46

answered Nov 27, 2015 at 10:57

Oleh Kudinov

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1 Comment

Mohammed Awad Over a year ago

Property 'self.selectedserver' not initialized at implicitly generated super.init call

Kristian Sthefan Cortes Prieto · Accepted Answer · 2015-11-27 18:33:04Z

0

Ok, I can do this with this code, only check when viewWillDisapear and call the parent of this view controller in the navicationController:

override func viewWillDisappear(animated: Bool) {
    if ((self.navigationController!.viewControllers.last?.isKindOfClass(ActivityMyViewController)) == true){
        let backView:MyViewController = self.navigationController!.viewControllers.last as! MyDetailViewController
        backView // do whatever you want
    }

}

I hope this code can help you, good luck

answered Nov 27, 2015 at 18:33

Kristian Sthefan Cortes Prieto

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Comments

Mohammed Awad · Accepted Answer · 2015-11-28 08:48:57Z

0

thanks guys for helping ;)

it was very simple

i just use then when it comeback ^^"

override func viewWillAppear(animated: Bool) {
    selectedServer.setTitle(selectedserv, forState: UIControlState.Normal)
}

answered Nov 28, 2015 at 8:48

Mohammed Awad

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