Adding a Decimal Point button to the calculator app - swift

Question

Can someone please add the code to this so I'm able to add a decimal point button?
This is what I have so far, can someone please fill in the code required for the decimal point button. so I can learn from it. please view over the code and let me know what you think.
import UIKit
class ViewController: UIViewController {
var numberOnScreen:Double = 0;
var previousNumber:Double = 0;
var preformingMath = false
var operation = 0;
#IBOutlet weak var label: UILabel!
#IBAction func numbers(_ sender: UIButton)
{
if preformingMath == true
{
label.text = String(sender.tag-1)
numberOnScreen = Double(label.text!)!
preformingMath = false
}
else
{
label.text = label.text! + String(sender.tag-1)
numberOnScreen = Double(label.text!)!
}
}
#IBAction func buttons(_ sender: UIButton)
{
if label.text != "" && sender.tag != 11 && sender.tag != 16
{
previousNumber = Double(label.text!)!
if sender.tag == 12 //Divide
{
label.text = "/";
}
else if sender.tag == 13//Multiply
{
label.text = "x";
}
else if sender.tag == 14 //Minus
{
label.text = "-";
}
else if sender.tag == 15 //Plus
{
label.text = "+";
}
operation = sender.tag;
preformingMath = true;
}
else if sender.tag == 16
{
if operation == 12
{
label.text = String(previousNumber / numberOnScreen)
}
else if operation == 13
{
label.text = String(previousNumber * numberOnScreen)
}
else if operation == 14
{
label.text = String(previousNumber - numberOnScreen)
}
else if operation == 15
{
label.text = String(previousNumber + numberOnScreen)
}
}
else if sender.tag == 11
{
label.text = ""
previousNumber = 0;
numberOnScreen = 0;
operation = 0;
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
}

Answer 1

Add this #IBAction to your code and hook it to your . button.
If the user presses . before any numbers, the display will be set to 0..
If there are numbers in the display, then . will be appended to the display if there isn't already a decimal point in the number.
Finally, the numberOnScreen will be updated.
#IBAction func decimal(_ sender: UIButton) {
if preformingMath || label.text!.isEmpty
{
label.text = "0."
preformingMath = false
}
else
{
if !label.text!.contains(".") {
label.text = label.text! + "."
}
}
numberOnScreen = Double(label.text!)!
}