Counting up/down numbers animation

Question

I have an UIPageViewController with a number in the center of each VC in it.

I want that when I swipe from view to view, the number will begin

Answer 1

Do not overcomplicate with timers and invalidations, etc.

extension UILabel {    
    func countAnimation(upto: Double) {
        let from: Double = text?.replace(string: ",", replacement: ".").components(separatedBy: CharacterSet.init(charactersIn: "-0123456789.").inverted).first.flatMap { Double($0) } ?? 0.0
        let steps: Int = 20
        let duration = 0.350
        let delay = duration / Double(steps)
        let diff = upto - from
        for i in 0...steps {
            DispatchQueue.main.asyncAfter(deadline: .now() + delay * Double(i)) {
                self.text = "\(from + diff * (Double(i) / Double(delay)))"
            }
        }
    }
}