animating circular UIBezierPath without rounding the stroke - ios

Question

I'm trying to add an animation to my UIBezierPath, but I want to keep the hard edges my current fillPath is creating, here's a screenshot of what the result should look like:
I did manage to get one animation working correctly using a slightly modified version of this code:
// create an object that represents how the curve
// should be presented on the screen
let progressLine = CAShapeLayer()
progressLine.path = ovalPath.CGPath
progressLine.strokeColor = UIColor.blueColor().CGColor
progressLine.fillColor = UIColor.clearColor().CGColor
progressLine.lineWidth = 10.0
progressLine.lineCap = kCALineCapRound
// add the curve to the screen
self.view.layer.addSublayer(progressLine)
// create a basic animation that animates the value 'strokeEnd'
// from 0.0 to 1.0 over 3.0 seconds
let animateStrokeEnd = CABasicAnimation(keyPath: "strokeEnd")
animateStrokeEnd.duration = 3.0
animateStrokeEnd.fromValue = 0.0
animateStrokeEnd.toValue = 1.0
// add the animation
progressLine.addAnimation(animateStrokeEnd, forKey: "animate stroke end animation")
The above code is from: http://mathewsanders.com/animations-in-swift-part-two/
It did work, but the stroke it created was rounded.
The only examples/tutorials and other questions I could find on this matter, was using CAShapes. I'm currently not using CAShapes or layers. (I don't know if that's needed to make an animation work with this, but I figure I'd ask)
Here's my current code (without any animation). To draw my little circle chart.
class CircleChart: UIView {
var percentFill: Float = 99.00 {
didSet {
// Double check that it's less or equal to 100 %
if percentFill <= maxPercent {
//the view needs to be refreshed
setNeedsDisplay()
}
}
}
var fillColor: UIColor = UIColor.formulaBlueColor()
var chartColor: UIColor = UIColor.formulaLightGrayColor()
override func drawRect(rect: CGRect) {
// Define the center.
let center = CGPoint(x:bounds.width/2, y: bounds.height/2)
// Define the radius
let radius: CGFloat = max(bounds.width, bounds.height)
// Define the width of the circle
let arcWidth: CGFloat = 10
// Define starting and ending angles (currently unused)
let startAngle: CGFloat = degreesToRadians(-90)
let endAngle: CGFloat = degreesToRadians(270)
// 5
var path = UIBezierPath(arcCenter: center,
radius: bounds.width/2 - arcWidth/2,
startAngle: startAngle,
endAngle: endAngle,
clockwise: true)
// 6
path.lineWidth = arcWidth
chartColor.setStroke()
path.stroke()
//Draw the fill-part
//calculate the arc for each per percent
let arcLengthPerPercent = degreesToRadians(360/100)
//then multiply out by the actual percent
let fillEndAngle = arcLengthPerPercent * CGFloat(percentFill) + startAngle
//2 - draw the outer arc
var fillPath = UIBezierPath(arcCenter: center,
radius: bounds.width/2 - arcWidth/2,
startAngle: startAngle,
endAngle: fillEndAngle,
clockwise: true)
//3 - draw the inner arc
fillPath.addArcWithCenter(center,
radius: bounds.width/2 - arcWidth/2,
startAngle: fillEndAngle,
endAngle: startAngle,
clockwise: false)
//4 - close the path
fillPath.closePath()
fillColor.setStroke()
fillPath.lineWidth = arcWidth
fillPath.stroke()
}
}
What would be the best way to animate the fillPath? Or do I need to redo everything in CAShapes and layers, to make it work?
Any help would be greatly appreciated.

Answer 1

If you want it square, why are you using progressLine.lineCap = kCALineCapRound? Just delete that line, and you'll get the default butt end (kCALineCapButt).