Custom Timer View in Swift

ClockView.swift

//: Playground - noun: a place where people can play

import UIKit
import XCPlayground

class ClockView: UIView {
    
    private var shapeLayer = CAShapeLayer()
    private var countDownTimer = NSTimer()
    private var timerValue = 900
    private var label = UILabel()
    
    override init (frame : CGRect) {
        super.init(frame : frame)
        
        self.createLabel()
    }
    
    required init(coder aDecoder: NSCoder) {
        fatalError("This class does not support NSCoding")
    }
    
    private func addCircle() {
        let circlePath = UIBezierPath(arcCenter: CGPoint(x: 160,y: 240), radius: CGFloat(100), startAngle: CGFloat(-M_PI_2), endAngle:CGFloat(2*M_PI-M_PI_2), clockwise: true)
        
        self.shapeLayer.path = circlePath.CGPath
        self.shapeLayer.fillColor = UIColor.clearColor().CGColor
        self.shapeLayer.strokeColor = UIColor.redColor().CGColor
        self.shapeLayer.lineWidth = 1.0
        
        self.layer.addSublayer(self.shapeLayer)
    }
    
    private func createLabel() {
        self.label = UILabel(frame: CGRect(x: 72, y: 220, width: 200, height: 40))
        
        self.label.font = UIFont(name: self.label.font.fontName, size: 40)
        self.label.textColor = UIColor.redColor()
        
        self.addSubview(self.label)
    }
    
    private func startAnimation() {
        let animation = CABasicAnimation(keyPath: "strokeEnd")
        animation.fromValue = 0
        animation.toValue = 1
        animation.duration = Double(self.timerValue)
        animation.fillMode = kCAFillModeForwards
        animation.removedOnCompletion = false
        
        self.shapeLayer.addAnimation(animation, forKey: "ani")
    }
    
    private func updateLabel(value: Int) {
        self.setLabelText(self.timeFormatted(value))
        self.addCircle()
    }
    
    private func setLabelText(value: String) {
        self.label.text = value
    }
    
    private func timeFormatted(totalSeconds: Int) -> String {
        let seconds: Int = totalSeconds % 60
        let minutes: Int = (totalSeconds / 60) % 60
        let hours: Int = totalSeconds / 3600
        return String(format: "%02d:%02d:%02d", hours, minutes, seconds)
    }
    
    // Needs @objc to be able to call private function in NSTimer.
    @objc private func countdown(dt: NSTimer) {
        self.timerValue--
        if self.timerValue < 0 {
            self.countDownTimer.invalidate()
        }
        else {
            self.setLabelText(self.timeFormatted(self.timerValue))
        }
    }
    
    func setTimer(value: Int) {
        self.timerValue = value
        self.updateLabel(value)
    }
    
    func startClockTimer() {
        //self.countDownTimer.invalidate()
        self.countDownTimer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("countdown:"), userInfo: nil, repeats: true)
        self.startAnimation()
        
    }
    
}

let view = ClockView()
view.backgroundColor = UIColor.whiteColor()
view.frame = CGRect(x: 0, y: 0, width: 320, height: 480)

view.setTimer(10)
view.startClockTimer()

XCPlaygroundPage.currentPage.liveView = view

Set Timer in swift latest version 3.0 or later. Click here for more information about swift code.