How to use drawRect in a particular area?

Question

I used this topic's animation in my project. The problem is I want to use a particular area for circle(grey area). To do it, I added a view(grey area) and the code is shown below. But it is locating different positions on x axis every time.(y is fixed). The second problem is I want to use the circle around the text. To do it, I placed the text and view to centre of the screen both vertically and horizontally. How can I fix these two problems?

Problem screenshots

These are the code that I used.

override init(frame: CGRect) {
        super.init(frame: frame)
        self.backgroundColor = UIColor.clearColor()

        // Use UIBezierPath as an easy way to create the CGPath for the layer.
        // The path should be the entire circle.
        let circlePath = UIBezierPath(arcCenter: CGPoint(x: frame.size.width / 2.0, y: frame.size.height / 2.0), radius: (frame.size.width - 10)/2, startAngle: 0.0, endAngle: CGFloat(M_PI * 2.0), clockwise: true)

        // Setup the CAShapeLayer with the path, colors, and line width

        circleLayer.path = circlePath.CGPath
        circleLayer.fillColor = UIColor.clearColor().CGColor
        circleLayer.strokeColor = randomColor().CGColor
        circleLayer.lineWidth = 40;

        // Don't draw the circle initially
        circleLayer.strokeEnd = 0.0

        // Add the circleLayer to the view's layer's sublayers
        layer.addSublayer(circleLayer)
    }


func animateCircle(duration: NSTimeInterval) {
        // We want to animate the strokeEnd property of the circleLayer
        let animation = CABasicAnimation(keyPath: "strokeEnd")

        // Set the animation duration appropriately
        animation.duration = duration

        // Animate from 0 (no circle) to 1 (full circle)
        animation.fromValue = 0
        animation.toValue = 1

        // Do a linear animation (i.e. the speed of the animation stays the same)
        animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)

        // Set the circleLayer's strokeEnd property to 1.0 now so that it's the
        // right value when the animation ends.
        circleLayer.strokeEnd = 1.0

        // Do the actual animation
        circleLayer.addAnimation(animation, forKey: "animateCircle")
    }

func addCircleView() {
        let diceRoll = CGFloat(Int(arc4random_uniform(7))*50)

        // Create a new CircleView
        var circleView = CircleView(frame: CGRect(x: view.frame.origin.x/2, y: view.frame.origin.y/2, width: 200, height: 200))

       extraView.addSubview(circleView)
        println(view.frame.width)
        println(view.frame.height)

        // Animate the drawing of the circle over the course of 1 second
        circleView.animateCircle(1.0)
    }

Can you add more your code? I don't know what your problem. – Long Pham Aug 22 '15 at 16:22 — Long Pham, Aug 22 '15 at 16:22

score 1 · Accepted Answer · answered Aug 22 '15 at 23:42

Problem is Auto layout. You forgot set layout for circleView <=> extraView. See the code below.

func addCircleView() {
        let diceRoll = CGFloat(Int(arc4random_uniform(7))*50)

        // Create a new CircleView
        var circleView = CircleView(frame: CGRect(x: view.frame.origin.x/2, y: view.frame.origin.y/2, width: 200, height: 200))

        extraView.addSubview(circleView)
        println(view.frame.width)
        println(view.frame.height)

        let constCenterX = NSLayoutConstraint(item: circleView, attribute: .CenterX, relatedBy: .Equal, toItem: extraView, attribute: .CenterX, multiplier: 1, constant: 0)

        let constCenterY = NSLayoutConstraint(item: circleView, attribute: .CenterY, relatedBy: .Equal, toItem: extraView, attribute: .CenterY, multiplier: 1, constant: 0)

        self.view.addConstraints([constCenterX, constCenterY])

        // Animate the drawing of the circle over the course of 1 second
        circleView.animateCircle(1.0)

        //circleView.textLabel?.text = "Hello World!"
}

BTW: For the second question you should create a UILabel (centerX & centerY) in CircleView. Hope that helps!

How to use drawRect in a particular area?

1 Answers1