Can't pass a variable to second viewcontroller

Question

I'm trying to assign a value to a variable when a button is pressed and then send it to my second viewcontroller.

I'm having trouble passing a variable (int) from my first viewcontroller(FirstViewController.swift) to my secondcontroller(ViewController.swift).

My entry point is FirstViewController.swift

This is my FirstViewController.swift code:

import UIKit

var language:Int = 0

class FirstViewController: UIViewController {

@IBAction func dutch(sender: AnyObject) {
    language = 1
    println(language)//check in console
}

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
}

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

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    var soundsVC = segue.destinationViewController as! ViewController

    soundsVC.languageSelected = language
}

The @IBAction func dutch gets activated when a button is pressed, after that has happened it should change the value of language to 1.

import UIKit
import AVFoundation

class ViewController: UIViewController {

var languageSelected:Int = 0

@IBAction func controleFunc(sender: AnyObject) {
    println(languageSelected)
    println(language)
}

override func viewDidLoad() {
    super.viewDidLoad()
    self.view.backgroundColor = UIColor(patternImage: UIImage(named: "background.jpg")!)
    // Do any additional setup after loading the view, typically from a nib.
    println(languageSelected)
}

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



}

My output is:

0 //languageSelected
1 //language
0 //languageSelected if the controle function is activated (controleFunc)
1 //language if the controle function is activated (controleFunc)

I just started learning Swift, so I don't really know why languageSelected won't take the value of language. Is it because I declare languageSelected:Int = 0 at the top of ViewController.swift? I have tried to change that to languageSelected:Int = language, but unfortunately I had the same results.

Thanks! Sezer

Answer 1

viewDidLoad() is happening before the prepareForSegue(), if you want to use the state that's passed in, either override the setter (as below) and do something with it, or do it in viewWillAppear()

var languageSelected:Int = 0 {
    didSet {
        print("The language is: \(languageSelected)")
    }
}

Answer 2

I’m not 100% sure exactly how you’ve got everything set up, but I think you have the same button both starting the segue and calling the function dutch() when it’s pressed. I don’t think you’re guaranteed that dutch() will get called first before prepareForSegue(), but your code depends on them getting called in that order.

I’d remove dutch() (make sure you disconnect it on the storyboard too) and just pass the value directly from prepareForSegue(). If you have more that one button starting a segue, you can find out which one started it by casting the sender parameter as UIButton and checking its currentTitle property. Or, you can just check the segue identifier, whatever you prefer.

Hope this helps!