Styjun

I'm attempting to initialize this ViewController class. I am not using the MVC design strategy so ignore the bad conventions used (if any).

How do I initialize this class properly?

Error: 'required' initializer 'init(coder:)' must be provided by subclass of 'UIViewController'

Context: This is a calculator app that when any of the buttons are pressed. It will go find the senders title and simply put if one of the three vars are nil, it will store it in that optional.

import UIKit

class ViewController: UIViewController 

 override func viewDidLoad() 
 super.viewDidLoad()
 // Do any additional setup after loading the view.
 

 @IBOutlet weak var answerLabel: UILabel!
 //global vars for all funcs
 var selection1: Int? 
 didSet answerLabel.text = String(selection1!) 
 
 var selection2: String? 
 didSet answerLabel.text = selection2! 
 
 var selection3: Int? 
 didSet answerLabel.text = String(selection3!) 
 

 var answer: Int 
 didSet answerLabel.text = String(answer) 
 


 init() 


 



 @IBAction func touchButton(_ sender: UIButton) 
 if selection1 == nil 
 selection1 = Int(sender.currentTitle!)
 print("Selection set in first pos.")
 else if selection2 == nil 
 selection2 = sender.currentTitle
 else if selection3 == nil 
 selection3 = Int(sender.currentTitle!)
 else 
 calculate(firstNum: selection1!, operation: selection2!, secondNum: selection3!)
 
 

 func calculate(firstNum: Int, operation: String, secondNum: Int) 
 switch operation 
 case "+":
 answer = firstNum + secondNum
 case "-":
 answer = firstNum - secondNum
 case "x":
 answer = firstNum * secondNum
 case "/":
 answer = firstNum / secondNum
 default:
 answerLabel.text = "Something went wrong!"
 
 

Initialization depends on a couple of condition.

1. If you are using storyboard, you can just remove the init and your VC will have default initializer. Make sure either all of your properties have default value or they are optional.


2. If you are using xib or just creating view programmatically you can have custom convenience initializer where you pass some extra data this way.

class MyViewController: ViewController 
 var answer: Int
 convenience init(answer: Int) 
 self.init()

 self.answer = answer
 // Do other setup
 

Your controller is being instantiated from the storyboard. A safe place to configure initial views is during the controller's call to viewDidLoad, ie:

override func viewDidLoad() 
 super.viewDidLoad()
 // configure your views and subviews here