Recall drawRect after view is recalled - ios

Question

I have a view that is using drawRect to draw a round timer.
In its superview there's a button that pushes another VC to the screen.
The problem is when the user clicks the back button, the timer (which is drawn using drawRect) is automatically starting with the toValue value instad of the fromValue. I want it to be redrawed exactly as it is drawn when I first launch the view.
Does anybody know how can I achieve that?
Thank you!
Code:
class CountDownTimer: UIView {
public var backgroundStrokeColor: CGColor = UIColor.white.cgColor
public var backgroundFillColor: CGColor = UIColor.clear.cgColor
public var backgroundLineWidth: CGFloat = 15
public var timeLeftSrtokeColor: CGColor = UIColor.red.cgColor
public var timeLeftFillColor: CGColor = UIColor.clear.cgColor
public var timeLeftLineWidth: CGFloat = 10
public var textColor: UIColor = UIColor.white
public var textFont: UIFont = UIFont.balooRegular(10.0)
fileprivate var timeLeft: TimeInterval = 0
fileprivate var endDate: Date?
fileprivate var timeLeftShapeLayer: CAShapeLayer?
fileprivate var bgShapeLayer: CAShapeLayer?
fileprivate var timeLabel: UILabel?
fileprivate var timer = Timer()
fileprivate let strokeIt = CABasicAnimation(keyPath: "strokeEnd")
//MARK: - UIView
override func draw(_ rect: CGRect) {
drawBgShape()
drawTimeLeftShape()
addTimeLabel()
strokeIt.toValue = 1 //"fromValue" is set in "startTimer(duration, timerProgress)
strokeIt.duration = self.timeLeft
// add the animation to your timeLeftShapeLayer
timeLeftShapeLayer?.add(strokeIt, forKey: nil)
// define the future end time by adding the timeLeft to now Date()
}
//MARK: - Public
public func startTimer(duration: TimeInterval, timerProgress: Double) {
self.timeLeft = duration
endDate = Date().addingTimeInterval(timeLeft)
timer = Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(updateTime), userInfo: nil, repeats: true)
strokeIt.fromValue = timerProgress
}
//MARK: - Private
fileprivate func drawBgShape() {
//we initialize and add the layer only if there is not initialized
if(bgShapeLayer == nil){
bgShapeLayer = CAShapeLayer()
self.layer.addSublayer(bgShapeLayer!)
}
bgShapeLayer?.path = UIBezierPath(arcCenter: CGPoint(x: self.frame.midX , y: self.frame.midY), radius:
min((frame.width - self.timeLeftLineWidth)/2, (frame.height - self.timeLeftLineWidth)/2), startAngle: -90.degreesToRadians, endAngle: 270.degreesToRadians, clockwise: true).cgPath
bgShapeLayer?.strokeColor = self.backgroundStrokeColor
bgShapeLayer?.fillColor = self.backgroundFillColor
bgShapeLayer?.lineWidth = self.backgroundLineWidth
}
fileprivate func drawTimeLeftShape() {
//we initialize and add the layer only if there is not initialized
if(timeLeftShapeLayer == nil){
timeLeftShapeLayer = CAShapeLayer()
self.layer.addSublayer(timeLeftShapeLayer!)
}
timeLeftShapeLayer?.path = UIBezierPath(arcCenter: CGPoint(x: self.frame.midX , y: self.frame.midY), radius:
min((frame.width - self.timeLeftLineWidth)/2, (frame.height - self.timeLeftLineWidth)/2), startAngle: -90.degreesToRadians, endAngle: 270.degreesToRadians, clockwise: true).cgPath
timeLeftShapeLayer?.strokeColor = self.timeLeftSrtokeColor
timeLeftShapeLayer?.fillColor = self.timeLeftFillColor
timeLeftShapeLayer?.lineWidth = self.timeLeftLineWidth
}
fileprivate func addTimeLabel() {
//we initialize and add the UILabel only if there is not initialized
if(timeLabel == nil){
timeLabel = UILabel()
self.addSubview(timeLabel!)
}
timeLabel?.frame = CGRect(x: self.frame.midX-50 ,y: self.frame.midY-25, width: 100, height: 50)
timeLabel?.adjustsFontSizeToFitWidth = true
timeLabel?.textAlignment = .center
timeLabel?.text = self.timeLeft.stringTime
timeLabel?.textColor = self.textColor
timeLabel?.font = self.textFont
}
//MARK: - Actions
#objc fileprivate func updateTime() {
if timeLeft > 0 {
timeLeft = endDate?.timeIntervalSinceNow ?? 0
timeLabel?.text = self.timeLeft.stringTime
} else {
timeLabel?.text = self.timeLeft.stringTime
timer.invalidate()
}
}
}