Pop-ups

Hello, I made a calculator application and I need a popup window to appear when the number 54 appears. Can you tell me how to implement this?

Thanks in advance

import UIKit

var x: Double = 0
var y: Double = 0

var enterFlag = 1
var yFlag = 1

var decimalPoint = 0

var power = 1

var operationActive = 0



class ViewController: UIViewController {

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

    @IBAction func digitals(_ sender: UIButton) {
        print("Цифра \(sender.tag)")
        
        if enterFlag == 1 {
            x = 0
            enterFlag = 0
        }
        
        if decimalPoint == 0 {
            x = x * 10 + Double(sender.tag)
            
            switch String(x) {
            case let z where z.hasSuffix(".0"):
                self.result.text = " " + String(Int(x))
            default:
                self.result.text = " " + String(x)
            }
        }else{
            x = x + Double(sender.tag)/pow(10, Double(power))
            power += 1
            
            switch String(x) {
            case let z where z.hasSuffix(".0"):
                self.result.text = " " + String(Int(x))
            default:
                self.result.text = " " + String(x)
            }
        }
    }
    
    @IBAction func operation(_ sender: UIButton) {
        if enterFlag != 1 && yFlag == 1 {
            switch operationActive {
            case 1001:
                x = y + x
            case 1002:
                x = y - x
            case 1003:
                x = y * x
            case 1004:
                x = y / x
            default:
                self.result.text = " " + String(x)
            }
        }
        
        operationActive = sender.tag
        y = x
        yFlag = 1
        enterFlag = 1
        switch String(x) {
        case let z where z.hasSuffix(".0"):
            self.result.text = " " + String(Int(x))
        default:
            self.result.text = " " + String(x)
        }
        
        decimalPoint = 0
        power = 1
        
    }
    
    @IBAction func decimal(_ sender: Any) {
        if decimalPoint == 0 {
            decimalPoint = 1
        }
    }
    
    @IBAction func claer(_ sender: Any) {
        decimalPoint = 0
            x = 0
            y = 0
            
            switch String(x) {
            case let z where z.hasSuffix(".0"):
                self.result.text = " " + String(Int(x))
            default:
                self.result.text = " " + String(x)
            }
            enterFlag = 1
            yFlag = 1
            
            power = 1
    }
    
    @IBOutlet weak var result: UILabel!
    
    
    @IBAction func inverse(_ sender: Any) {
        x = -x
        switch String(x) {
        case let z where z.hasSuffix(".0"):
            self.result.text = " " + String(Int(x))
        default:
            self.result.text = " " + String(x)
    }
    }
    
    
    @IBOutlet weak var image: UIImageView!
}