import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var calcScreen: UITextField!

    var first = 0
    var second = 0
    var operation = ""
    var answer = 0

    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 pressedOne(sender: UIButton) {
        calcScreen.text = "1"
        if first == 0 { first = 1} else {second = 1}

    }


    @IBAction func pressedTwo(sender: UIButton) {
        calcScreen.text = "2"
        if first == 0 { first = 2} else {second = 2}
    }


    @IBAction func pressedThree(sender: UIButton) {
        calcScreen.text = "3"
        if first == 0 { first = 3} else {second = 3}
    }


    @IBAction func clearScreen(sender: UIButton) {
        calcScreen.text = ""
        first = 0
        second = 0
    }


    @IBAction func add(sender: UIButton) {
        operation = "add"
    }



    @IBAction func minus(sender: UIButton) {
        operation = "minus"

    }


    @IBAction func equals(sender: UIButton) {
        if operation == "minus"{
            answer = first - second
            calcScreen.text = "\(answer)"
        }
        if operation == "add" {
            answer = first + second
            calcScreen.text = "\(answer)"
        }
    }




}