Passing Data Between Views in One Viewcontroller in Swift

Passing data between views in ONE ViewController in Swift

EDIT: Sorry, when I created this answer I was having ViewControllers in mind. A much easier way would be to create a method in SomeView and talk directly to it.

Example:

class MainViewController: UIViewController {

    var view1: SomeView!
    var view2: SomeView!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Create the views here
        view1 = SomeView()
        view2 = SomeView()

        view.addSubview(view1)
        view.addSubview(view2)
    }

    @IBAction func someAction(sender: UIButton) {
        view1.changeString("blabla")
    }
}

class SomeView: UIView {

    var someString: String?

    func changeString(someText: String) {
        someString = someText
    }
}

Delegate:

First you create a protocol:

protocol NameOfDelegate: class {     // ": class" isn't mandatory, but it is when you want to set the delegate property to weak
    func someFunction()              // this function has to be implemented in your MainViewController so it can access the properties and other methods in there
}

In your Views you have to add:

class SomeView: UIView, NameOfDelegate {

    // your code

    func someFunction() {

        // change your slider settings
    }
}

And the last step, you'll have to add a property of the delegate, so you can "talk" to it. Personally I imagine this property to be a gate of some sort, between the two classes so they can talk to each other.

class MainViewController: UIViewController {

    weak var delegate: NameOfDelegate?

    @IBAction func button(sender: UIButton) {
        if delegate != nil {
            let someString = delegate.someFunction()
        }
    }
}

I used a button here just to show how you could use the delegate. Just replace it with your slider to change the properties of your Views

EDIT: One thing I forgot to mention is, you'll somehow need to assign SomeView as the delegate. But like I said, I don't know how you're creating the views etc so I can't help you with that.

Passing data between two views (in the same ViewController)

Let's say you have two views view1 and view2.
For example some data changed in view2 and you need to pass this data to view1. I'd do this with delegation pattern. So here's the setup:

protocol View2Delegate {
    func didChangeSomeData(data: String) 
}

Now in view2

class View2: UIView {

   var delegate: View2Delegate?

   var text: String = String() {
        didSet {
           self.delegate.didChangeSomeData(data: text)
        }
   }
}

and in view1

class View1: UIView, View2Delegate { 

     var textToChange: String = String()

     func didChangeSomeData(data: String) {
          // Do whatever you want with that changed data from view2
          textToChange = data
     }
}

and in your viewController

class MyViewController: UIViewController {
     var: view1 = View1()
     var: view2 = View2()

  func viewDidLoad() {
      super.viewDidLoad()
      view2.delegate = view1
  }

Now, if you don't really want to couple view1and view2, you could listen via the same pattern changes of view2 in ViewController and then pass it directly to the view1 via property accessor.

class MyViewController: UIViewController, View2Delegate {
     var: view1 = View1()
     var: view2 = View2()

  func viewDidLoad() {
      super.viewDidLoad()
      view2.delegate = self
  }

  func didChangeSomeData(data: String) {
        view1.textToChange = data
  }

More on protocols in the Apple's Documentation

Update

You could also go with Key Value Observing pattern. You could setup it like this:

class MyViewController: UIViewController {
     var view1 = View1()
     var view2 = View2()

     override func viewDidLoad() {
         super.viewDidLoad()

         let observation = view2.observe(\.text) { (observed, change) in
           if let newValue = change.newValue {
                view1.textToChange = newValue
           }
         }

     }

 }

Passing data between a ViewController to another ViewController with navigation controller Swift 5

If you are using segue, then add "segue_identifier" in storyboard and the in secondviewcontroller add:

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
             if segue.identifier == "segue_ identifier" {
                let mainTab = segue.destination as! tabBarController
                let nav = mainTab.viewControllers[0] as! UINavigationController
                let vc = nav.viewControllers.first as! HomeViewController
                vc.cid = cityId
            }
        }

Because your segue destination is UINavigationController, you need to send data to view controller like this

Passing Data Between View Controllers in Swift 4

Your problem is that your prepare methods never run because you never call them.

Look, when you call performSegue, then prepare(for segue: sender:) is called too, so you can override this method in your ViewController and because you're passing identifier as parameter of performSegue method you can determine what should happen if segue has this or this identifier

So, delete prepare for segue methods from IBActions

@IBAction func backButton(_ sender: Any) {
    if installer == "verified"{
        performSegue(withIdentifier: "main/login", sender: self)
    }
}

@IBAction func button1(_ sender: Any) {
    if installer == "verified"{
        performSegue(withIdentifier: "Button1", sender: self)
    }
}

instead override prepare(for segue: sender:) method of ViewController and inside specify what should happen if segue has "main/login" indentifier or "Button1":

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "main/login" {
        let mainController = segue.destination as! ViewController
        mainController.myvar = installer
    } else if segue.identifier == "Button1"
        let IPController = segue.destination as! IP_ModuleQuickStartViewController
        IPController.verified = installer
    }
}

Swift 3 - Passing data between a View Controller and after that to another 2

Before calling presentViewController add :

nextViewController.name = yourTextField.text

You could also delete the segue call. That is redundant.

Here is an example that I've used in the past :

    @IBAction func doSegue(_ sender: UIButton) {
        buttonTag = sender.tag

        let storyboard = UIStoryboard (name: "Main", bundle: nil)
        let resultVC = storyboard.instantiateViewController(withIdentifier: "ResultViewController")as! ResultViewController

        // Communicate with new VC - These values are stored in the destination
        // you can set any value stored in the destination VC here
        resultVC.firstValue = buttonTag
        resultVC.secondValue = randomOpponentValue()
        self.navigationController?.pushViewController(resultVC, animated: true)
    }

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