(Swift) interaction between the button and the pie chart : I am new to Swift and I hope to make interaction between the button and the pie chart. Let's say when I press button1(red line) for 10 times, button2(blue line) for 5 times, the pie chart's edge will show 2/3 of red and 1/3 of blue. the proportion of the two color will keep changing whenever the buttons are pressed. 

One more question, now one of the edge will show yellow color

(circleShape.strokeColor = UIColor.yellowColor().CGColor)
but the remaining part will be transparent. How can I automatically fill the remaining part of the edge with certain color?

Below is my code, thanks all! 



    override func viewDidLoad() {
        super.viewDidLoad()
        // round view
        let roundView = UIView(frame: CGRectMake(85, 100, 150, 150))
        roundView.backgroundColor = UIColor.whiteColor()
        roundView.layer.cornerRadius = roundView.frame.size.width / 2
        
        // bezier path
        let circlePath = UIBezierPath(arcCenter: CGPoint (x: roundView.frame.size.width / 2, y: roundView.frame.size.height / 2),
                                      radius: roundView.frame.size.width / 2,
                                      startAngle: CGFloat(-0.5 * M_PI),
                                      endAngle: CGFloat(1.5 * M_PI),
                                      clockwise: true)
        // circle shape
        let circleShape = CAShapeLayer()
        circleShape.path = circlePath.CGPath
        circleShape.strokeColor = UIColor.yellowColor().CGColor
        circleShape.fillColor = UIColor.clearColor().CGColor
        circleShape.lineWidth = 5
        // set start and end values
        circleShape.strokeStart = 0.0
        circleShape.strokeEnd = 0.5
        
        // add sublayer
        roundView.layer.addSublayer(circleShape)
        // add subview
        self.view.addSubview(roundView)
    }

    var num = 0

    @IBOutlet weak var Button1: UILabel!
    @IBOutlet weak var Button2: UILabel!
    
    @IBAction func B1(sender: UIButton) {
        num = Int(Button1.text!)!
        self.Button1.text = String(num + 1 )
    }
    
    @IBAction func B2(sender: UIButton) {
        num = Int(Button2.text!)!
        self.Button2.text = String(num + 1 )
    }
    
