UIButton inside UISegmentedControl action - ios

Question

I am continuing my calculation program to improve my skills in Swift code. Right now I have a problem: I want that an UISegmentedControl select the operator of my operations (+, - ecc..) and when one is selected a UIButton func calculate the values based on the decision of the UISegmentedControl.
Here is the code but is not working.
Thanks,
Matteo
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var firstNumber: UITextField!
#IBOutlet weak var secondNumber: UITextField!
#IBOutlet weak var resultButton: UIButton!
#IBOutlet weak var resultNumber: UILabel!
#IBOutlet weak var operatorSelector: UISegmentedControl!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func operatorSelectorChanged(_ sender: UISegmentedControl) {
switch operatorSelector.selectedSegmentIndex {
case 0:
#IBAction func resultFunction(_ sender: AnyObject) {
if let firstNumberConv :Int = Int(firstNumber.text!), let secondNumberConv :Int = Int(secondNumber.text!) {
let result = firstNumberConv + secondNumberConv
resultNumber.text = "\(result)"
} else { resultNumber.text = "Inserire solo valori numerici"}
}
case 1:
#IBAction func resultFunction(_ sender: AnyObject) {
if let firstNumberConv :Int = Int(firstNumber.text!), let secondNumberConv :Int = Int(secondNumber.text!) {
let result = firstNumberConv - secondNumberConv
resultNumber.text = "\(result)"
} else { resultNumber.text = "Inserire solo valori numerici"}
}
default:
break;
}
}
}

Answer 1

Try removing the lines with #IBAction func ... inside your switch cases.
I think your #IBAction func operatorSelectorChanged should look something like this:
#IBAction func operatorSelectorChanged(_ sender: UISegmentedControl) {
switch operatorSelector.selectedSegmentIndex {
case 0:
if let firstNumberConv = Int(firstNumber.text!), let secondNumberConv = Int(secondNumber.text!) {
let result = firstNumberConv + secondNumberConv
resultNumber.text = "\(result)"
} else { resultNumber.text = "Inserire solo valori numerici"}
case 1:
if let firstNumberConv = Int(firstNumber.text!), let secondNumberConv = Int(secondNumber.text!) {
let result = firstNumberConv - secondNumberConv
resultNumber.text = "\(result)"
} else { resultNumber.text = "Inserire solo valori numerici"}
default:
break;
}
}

Answer 2

A possible solution for your problem is to define an IBAction that calculates the result of adding/subtracting two numbers
#IBAction func calculate(_ sender: AnyObject) {
if let a = Int(firstNumber.text!), let b = IntsecondNumber.text!) {
switch operatorSelector.selectedSegmentIndex {
case 0:
resultNumber.text = "\(a+b)"
case 1:
resultNumber.text = "\(a-b)"
default:
print("❗️unknown operator selected")
}
}
}
You could then bind this action to the sent events from your user interface: for example the Editing Changed event of your text fields (firstNumber and secondNumber) and the Value Changed of your segmented control (operatorSelector)
I created an example project that illustrates this: https://github.com/dev1an/calculator
How to bind multiple events to one IBAction
Write down the IBAction in code (like the calculate action I wrote above). Go to your storyboard and open the assistent editor (AltCmdEnter). Select a UI element (like a text field) in the interface builder. Open the Connections Inspector (AltCmd6) and drag from the circle next to a sent event (for example Editing Changed) to your IBAction code.