     
     func stopContinuous(_ sender: UIButton) {
         // When dragged outside, stop the timer.
-        continuousTimer?.invalidate()
+        continuousTimer = nil
     }
     
     func increaseValue() {

    
    internal func decrease(_ sender: UIButton) {
        sender.backgroundColor = UIColor(white: 1.0, alpha: 0.0)
        continuousTimer?.invalidate()
        continuousTimer = nil
        decreaseValue()
    }
    
    internal func increase(_ sender: UIButton) {
        sender.backgroundColor = UIColor(white: 1.0, alpha: 0.0)
        continuousTimer?.invalidate()
        continuousTimer = nil
        increaseValue()
    }

            increaseButton.isEnabled = false
            decreaseButton.isEnabled = true
            increaseLayer.strokeColor = UIColor.gray.cgColor
            continuousTimer = nil
        } else if value <= minimumValue {
            decreaseButton.isEnabled = false
            increaseButton.isEnabled = true
            decreaseLayer.strokeColor = UIColor.gray.cgColor
            continuousTimer = nil
        } else {
            increaseButton.isEnabled = true
            decreaseButton.isEnabled = true
