Display an array of CAShapeLayers - ios

Question

I have created an array of CAShapeLayers in order to draw different portions of an arc in different colors on different layers, this is my code :
import UIKit
class ViewController: UIViewController {
var level = 0.0
var old_level = 0.75
var progressLayer: [CAShapeLayer] = []
var circle = UIView()
override func viewDidLoad() {
circle = UIView(frame: CGRect(x: 0, y: 0, width: view.frame.size.width, height: view.frame.size.height))
view.addSubview(circle)
update_curve(value: 10)
update_curve(value: 20)
update_curve(value: 10)
}
func update_curve(value: Double){
level = value*(1.5/100)+0.75
progressLayer.append(CAShapeLayer())
var progressPath = UIBezierPath(arcCenter: CGPoint(x: progressLayer[layerindex].frame.size.width/2, y: progressLayer[layerindex].frame.size.height/2), radius: CGFloat(100), startAngle: CGFloat(M_PI*old_level), endAngle:CGFloat(level*M_PI), clockwise: true)
circle.layer.addSublayer(progressLayer[layerindex])
progressLayer[layerindex].frame = view.bounds
progressLayer[layerindex].path = progressPath.cgPath
progressLayer[layerindex].fillColor = UIColor.clear.cgColor
progressLayer[layerindex].strokeColor = generateRandomColor()
progressLayer[layerindex].lineWidth = 20.0
let animation2 = CABasicAnimation(keyPath: "strokeEnd")
animation2.fromValue = 0.0
animation2.toValue = 1.0
animation2.duration = 1
animation2.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
progressLayer[layerindex].add(animation2, forKey: "drawLineAnimation")
layerindex += 1
old_level = level
}
func generateRandomColor() -> UIColor {
let hue : CGFloat = CGFloat(arc4random() % 256) / 256 // use 256 to get full range from 0.0 to 1.0
let saturation : CGFloat = CGFloat(arc4random() % 128) / 256 + 0.5 // from 0.5 to 1.0 to stay away from white
let brightness : CGFloat = CGFloat(arc4random() % 128) / 256 + 0.5 // from 0.5 to 1.0 to stay away from black
return UIColor(hue: hue, saturation: saturation, brightness: brightness, alpha: 1)
}
}
But when I run this code, nothing appears on the screen of the iphone, but I don't get an error. What am I doing wrong?

Answer 1

I have just realised that the frame of the progressLayer was being defined after the defining the progressPath. The code for the update_curve function should be :
func update_curve(value: Double){
level = value*(1.5/100)+0.75
progressLayer.append(CAShapeLayer())
progressLayer[layerindex].frame = view.bounds
var progressPath = UIBezierPath(arcCenter: CGPoint(x: progressLayer[layerindex].frame.size.width/2, y: progressLayer[layerindex].frame.size.height/2), radius: CGFloat(100), startAngle: CGFloat(M_PI*old_level), endAngle:CGFloat(level*M_PI), clockwise: true)
circle.layer.addSublayer(progressLayer[layerindex])
progressLayer[layerindex].path = progressPath.cgPath
progressLayer[layerindex].fillColor = UIColor.clear.cgColor
progressLayer[layerindex].strokeColor = generateRandomColor()
progressLayer[layerindex].lineWidth = 20.0
let animation2 = CABasicAnimation(keyPath: "strokeEnd")
animation2.fromValue = 0.0
animation2.toValue = 1.0
animation2.duration = 1
animation2.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
progressLayer[layerindex].add(animation2, forKey: "drawLineAnimation")
layerindex += 1
old_level = level
}