Time delay for a loop in Swift XCode

Question

I'm a fairly new coder which is trying to push my limits, I'm trying to make an adventure capalist clone. If you're not too familiar it's practically just a tycoon game in the form of a UI. Anyways I've gotten stuck on how to get the money to multiple every few seconds.

import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var cash: UILabel!
    @IBOutlet weak var applePrice: UILabel!
    @IBOutlet weak var tomatoPrice: UILabel!
    @IBOutlet weak var berryPrice: UILabel!
    
    var cashTotal = 100
    var appletotal = 5
    var berrytotal = 10
    var tomatoTotal = 15
    var applemultiplier = 1
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    @IBAction func buyapple(_ sender: Any) {
        if cashTotal >= appletotal {
            cashTotal = cashTotal - tomatoTotal
            applemultiplier = applemultiplier + 1
            appletotal = appletotal * applemultiplier
            cash.text = "Cash: \(cashTotal)"
            applePrice.text = "Price: \(appletotal)"
        }

        while 0 == 0 {
            sleep(20)
            cashTotal = 5 * applemultiplier
            cash.text = "\(cashTotal)"
        
        }
    }

    @IBAction func buyberry(_ sender: Any) {
    }

    @IBAction func buytomato(_ sender: Any) {     
    }  
}

Answer 1

You should edit your question to explain what you mean by "...how to get the money to multiple every few seconds".

It looks like you want to increase the value in your cashTotal variable every 20 seconds.

You currently use sleep(). Don't ever use sleep() on the main thread of an interactive app. It causes your entire UI to freeze, and will likely cause the system to think your app has crashed and kill it.

You want to create a repeating Timer. Take a look at the Timer class reference, and in particular the method scheduledTimer(withTimeInterval:repeats:block:). That will let you create a repeating timer that fires every X seconds, and invokes the code in a closure that you provide.

Your current code, in addition to being used in a never-ending while loop (bad) with a sleep command (bad), also sets cashTotal = 5 * applemultiplier

If applemultiplier never changes, then that code will set cashTotal to the same value every time it fires.

Don't you really want to add some amount to cashTotal every time the timer fires? If you multiply it by an amount greater than one, you'll get exponential growth, which you probably don't want. (Say you have 10 dollars. Every 20 seconds you multiply that by 2. After 2 minutes (6 doublings) you'll have 10x2⁶, or 640 dollars. After 10 minutes (30 doublings) you'll have 10*2³⁰, or almost 11 billion dollars.)

Answer 2

This is a great project to learn from, and you're asking a good question. As others have said, you'll want to use a timer to update your game state periodically. Add a property to your view controller (or whatever class manages the game):

var gameTimer : Timer

and set it up when your game starts:

let updateInterval = 20.0
gameTimer = Timer.scheduledTimer(withTimeInterval: updateInterval, repeats: true) { timer in
    updateGameState()
}

Finally, add a function to actually do the updating:

func updateGameState() {
    // your update code here
}

(You could do the updating right in the closure that the timer runs, but it's good style to break it out into its own function.)

Now the timer will run updateGameState() every updateInterval seconds.