PreparetoSegue Button Command to Another ViewController Swift

Question

How do I preparetoSegue a button command to another ViewController? It seem my calculateButton is giving me an error code.

MainViewController

if (segue.identifier == "toCalculate") {

            let destViewController : CalcualteViewController = segue.destinationViewController as CalcualteViewController

            destViewController.calculateButton(sender: UIButton) {

                let dataone = data1.text.toInt() ?? 0

                let datatwo = data2.text.toInt() ?? 0

                let answercalculation = dataone * datatwo

                answer.text = "\(answercalculation)" + " psi"

            }

CalculateViewController

class CalcualteViewController: UIViewController {

    @IBOutlet weak var textlabel: UILabel!

    @IBOutlet var answer: UITextField!

    @IBOutlet var data1: UITextField!

    @IBOutlet var data2: UITextField!

    @IBAction func calculateButton(sender: AnyObject) {

    }

Answer 1

destViewController.calculateButton is a method of CalculateViewController. You have a closure hanging off the end of it when it doesn't accept any arguments accept sender: AnyObject. Move your logic into the CalculateViewController.

@IBAction func calculateButton(sender: AnyObject) {
       let dataone = data1.text.toInt() ?? 0
       let datatwo = data2.text.toInt() ?? 0
       let answercalculation = dataone * datatwo
       answer.text = "\(answercalculation)" + " psi"
}

If you want to share the code across multiple controllers you could create an instance variable called var calculateButtonAction: ((UIButton) -> ())? and then set it in prepareForSegue:

destinationViewController.calculateButtonAction = { (sender) in
   let dataone = destinationViewController.data1.text.toInt() ?? 0
   let datatwo = destinationViewController.data2.text.toInt() ?? 0
   let answercalculation = dataone * datatwo
   destinationViewController.answer.text = "\(answercalculation)" + " psi"
}

And then call it from CalculatorViewController:

@IBAction func calculateButton(sender: AnyObject) {
     if let action = calculateButtonAction {
        action(sender)
     }
}

Better yet, create a BaseCalculatorViewController and subclass it for your controllers so you can have your subclasses inherit calculateButton.