Pass one variable from one viewcontroller to another viewcontroller

Question

I new to swift language and know this question is duplicated.I`ve found several similar question and answer, but i could not able to figure out the problem.

I want to pass the value of detectionString variable to ResultViewController from ScanViewController.

ScanViewcontroller as below:

import UIkit

class ScanViewController: UIViewController  {

    var detectionString : String!

    override func viewDidLoad() {
        super.viewDidLoad()

        detectionString = “SomeDetectedString”
    }

    override func prepareForSegue(segue: UIStoryboardSegue,sender: AnyObject!) {
        if (segue.identifier == "MySegue") {
            var svc = segue.destinationViewController as ResultViewController;
            svc.detectedString = detectionString
        }
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

The ResultViewController as below:

import UIkit

class ResultViewController: UIViewController {

    var detectedString: String!

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor=UIColor.whiteColor()
        println(detectedString)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

The println(detectedString) gives me no result. question is that how can get the variable from ScanViewController?

possible duplicate of Pass variables from one ViewController to another in Swift — jtbandes
– jtbandes, Commented Feb 8, 2015 at 6:00

Syed Tariq · Accepted Answer · 2015-02-08 08:15:28Z

This may sound bizarre but there is nothing wrong with your code BUT it does not work as is. I used your code identically and it ignored the segue. Then I embedded ScanViewController in a navigation controller in the storyboard. I also put a call to self.performSegueWithIdentifier("MySegue", sender: self) in the ScanViewController viewDidLoad to initiate the segue. Then everything works like a charm. Your prepareForSegue is fine. Yuvrajsinh's suggestion is fine but not necessary (I tried it after changing DetailVC to ResultViewController). Without the navigation controller nothing works. segue.identifier is a string and it will work in a straight Swift string comparison.

Here is the code for ScanViewController:

import UIkit

class ScanViewController: UIViewController  {

    var detectionString : String!

    override func viewDidLoad() {
        super.viewDidLoad()


        detectionString = "SomeDetectedString"
        println(detectionString)
        self.performSegueWithIdentifier("MySegue", sender: self)
    }

    override func prepareForSegue(segue: UIStoryboardSegue,sender: AnyObject!) {

        if (segue.identifier == "MySegue" || segue.identifier == "SegueFromButton") {
            println("prepareForSegue")
            var svc = segue.destinationViewController as ResultViewController;
            svc.detectedString = detectionString
            println("svc.detectedString: \(svc.detectedString)")
        }
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }


}

and for ResultViewController:

import UIkit

class ResultViewController: UIViewController {

    var detectedString: String!

    override func viewDidLoad() {
        println("Result Load View")
        super.viewDidLoad()
        self.view.backgroundColor=UIColor.whiteColor()
        println("detectedString in Result: \(detectedString)")
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

,Thank you for answer, really appreciate your help , it works as you described. beside this , i also tried to get access value of the variable by using appdelegate. Thank you again.

Yuvrajsinh · Accepted Answer · 2015-02-08 05:52:48Z

1

your segue.identifier == "MySegue" is some how not comparing in the way it should.

replace your code with following function and you are done.

override func prepareForSegue(segue: UIStoryboardSegue,sender: AnyObject!) {
    let segueName: String = segue.identifier!;
    if (segueName == "MySegue") {
        var svc = segue.destinationViewController as DetailVC;
        svc.detectedString = detectionString
    }
}

answered Feb 8, 2015 at 5:52

Yuvrajsinh

4,5841 gold badge20 silver badges32 bronze badges

1 Comment

Rustam Over a year ago

Thank you for your answer,if i trigger segue by @BIAction , i can get the value from first value. @IBAction func showsecond(sender: AnyObject) { self.performSegueWithIdentifier("MySegue", sender: nil) } It crashed whenever i tried to triger segue programatically.

duan · Accepted Answer · 2015-02-08 06:45:17Z

1

There are three options for you:

use prepareForSeguemethod to get the target ViewController and set up the property
set up delegate relationship between the two ViewControllers to communicate
set up Observer with NSNotificationCenter

answered Feb 8, 2015 at 6:45

duan

8,9453 gold badges53 silver badges73 bronze badges

1 Comment

Rustam Over a year ago

thank you, I tried delegate and it works for me too.

Collectives™ on Stack Overflow

Pass one variable from one viewcontroller to another viewcontroller

3 Answers 3

1 Comment

1 Comment

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related