Swift: Setting UI elements by preparing for segues inside if statements within a method

Question

Good evening. I'm creating my first own app (without following tutorials) that has clickable stuff in AR. I use touchesEnded to get the position of the touch and then I direct a segue if the touch is on an object. But depending on what is touched I want to set the target view controllers' labels, image views etc differently.

Question: Where do I call the prepare for segue method in order to do that or is there a simpler way? When I run the example code (below) I get a crash as a result of an error upon entering the segue saying that testLabel is nil (if I remove the prepare segue bit the segue works fine)

Explanations: 1. 'CaseViewController' is the name of the target view controller and the identifier of my segue 2. In CaseViewController I have connected a UILabel by ctrl + dragging it to the class and it is connected.

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

    let destinationVC = segue.destination as! CaseViewController
    destinationVC.testLabel.text = "setting of label test"
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {

    guard let touchLocation = touches.first?.location(in: sceneView),
        let hitNode = sceneView?.hitTest(touchLocation, options: nil).first?.node,
        let nodeName = hitNode.name
        else { return }

    if nodeName == imageNameArray[0] {

        performSegue(withIdentifier: "CaseViewController", sender: self)
        //Example: I would ideally want a prepare for segue method here to set the label for this statement only
    } else {
        print("Found no node connected to \(nodeName)")
        return
    }

    if nodeName == imageNameArray[1] {

        performSegue(withIdentifier: "CaseViewController", sender: self)
        //And another label setting for this statement etc.
    } else {
        print("Found no node connected to \(nodeName)")
        return
    }
    print(nodeName)



}

Thanks for reading my question. Kind regards.

Answer 1

The label is nil till teh VC loads

destinationVC.testLabel.text = "setting of label test"

so convert it to

destinationVC.lblText = "setting of label test"

//

class CaseViewController:UIViewController {
  var lblText = ""
}

then assign the value to the text inside viewDidLoad , although touch method is called continuously

Edit:

Use sender to send any value of any type from any if statement

performSegue(withIdentifier: "CaseViewController", sender:"lbl")

then in prepare cast it to it's type

destinationVC.lblText = sender as! String //