Pass data between ViewController without Segues - ios

Question

I am pretty new to swift development and have some problems understanding how to pass data between ViewController.
I want to build a simple music player app which has three views (Player, Playlists, Tracks).
At start the Player is shown to the user. From there the user can press a button and the Playlists view come up. Now he can select a playlist and the next view Tracks is displayed.
If he press on a track he gets back to the Player view and the track is playing. So I need to pass my track to my PlayerViewController.
Currently I'm using Segues to display each ViewController.
Player -> Playlists -> Tracks -> Player
But this will initialise the Player again which means that values/variables get reset. How can I avoid this?

Answer 1

If you are getting from view controller B to view controller C by saying present, then view controller C can speak to view controller B as its presentingViewController.

Answer 2

Try using Unwind segues to pass data i guess they can help you out.
An unwind segue (sometimes called exit segue) can be used to navigate
back through push, modal or popover segues (as if you popped the navigation
item from the navigation bar, closed the popover or dismissed the modally
presented view controller). On top of that you can actually unwind through
not only one but a series of push/modal/popover segues, e.g. "go back"multiple steps in your navigation hierarchy with a single unwind action.When you perform an unwind segue, you need to specify an action, which is an action method of the view controller you want to unwind to.
//ViewControllerA:
import UIKit
class ViewControllerA: UIViewController {
var dataRecieved: String? {
willSet {
labelOutlet.text = newValue
}
}
#IBOutlet weak var labelOutlet:UILabel!
#IBOutlet weak var nextButtonOutlet: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
#IBAction func nextButtonAction(_ sender:UIButton) {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let controller = storyboard.instantiateViewController(withIdentifier: "ViewControllerB") as! ViewControllerB
controller.dataPassed = labelOutlet.text
self.present(controller, animated: true, completion: nil)
}
// segue ViewControllerB -> ViewControllerA
#IBAction func unwindToThisView(sender: UIStoryboardSegue) {
if let sourceViewController = sender.source as? ViewControllerB {
dataRecieved = sourceViewController.dataPassed
}
}
}
//ViewControllerB
import UIKit
class ViewControllerB: UIViewController , UITextFieldDelegate{
#IBOutlet weak var textFieldOutlet: UITextField!
var dataPassed : String?
override func viewDidLoad() {
super.viewDidLoad()
textFieldOutlet.text = dataPassed
textFieldOutlet.delegate = self
}
// UITextFieldDelegate
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
// User finished typing (hit return): hide the keyboard.
textField.resignFirstResponder()
return true
}
func textFieldDidEndEditing(_ textField: UITextField) {
dataPassed = textField.text
}
}
//From the Return Button click control and drag to exit of the viewcontrollerB as show in the image.

Answer 3

To pass data between View Controllers, have this block in your code:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let feed = segue.destination as! SecondViewControllerName
feed.variableinsecondviewcontroller = variableincurrentviewcontroller
}
If that didn't help, you might need to elaborate on what exactly you want with your code...

Answer 4

Use struct class and access your object any where using the stuct object
Like this
struct SomeStruct { var name: String init(name: String) { self.name = name } } var aStruct = SomeStruct(name: "Bob") var bStruct = aStruct // aStruct and bStruct are two structs with the same value! bStruct.name = "Sue" println(aStruct.name) // "Bob" println(bStruct.name) // "Sue"