On Xcode, How do I increase the variable 'counter' by 1 every second as long as the screen is held?

Question

I've recently started learning and playing around with Xcode but I've been having some issues.

I need a variable speed to increase by 1 every second I hold the screen. I read the docs but I barely understood anything and a lot of the info looks irrelevant for what I'm doing. Here's the code I have right now:

class ViewController: UIViewController {\
    @IBOutlet weak var counterLabel: UILabel!
    var counter = 0
    // The number of seconds after which to update
    var speed = 1

    override func viewDidLoad() {
        super.viewDidLoad()
        counterLabel.text = "\(counter)"
    }

    @IBAction func screenHeld(_ sender: Any) {
        // Need to add code here
    }
}

Answer 1

• Create a global Timer variable. When the user touches the screen, the timer is started.
• The Timer will increment your global variable. Also check if your condition is met in the timer callback.
• When the user releases the finger from the screen, the timer is invalidated and the global variable is reset to zero.

Here is come untested code to get you started:

var timer: Timer?
var myCounter = 0

// Connect to the corresponding control or the tap recognizer.
@IBAction func screenBeginTouch(_ sender: Any)
{
    self.timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true)
    {
        timer in
        self.myCounter += 1
        // Check condition here
    }
}

// Connect to the corresponding control or the tap recognizer.
@IBAction func screenEndTouch(_ sender: Any)
{        
    self.timer?.invalidate()
    self.timer = nil
    self.myCounter = 0
}

Timer Apple Documentation