loadingCircleView

loadingCircleView.swift

final class LoadingCircleView: UIView {
    
    private var shapeLayer: CAShapeLayer!

    override func draw(_ rect: CGRect) {
        let center = CGPoint(x: bounds.width / 2, y: bounds.height / 2)
        let trackLayer = createTrackLayer(center: center, radius: 100, lineWidth: 10, strokeColor: .darkGray)
        layer.addSublayer(trackLayer)
        shapeLayer = createTrackLayer(center: center, radius: 100, lineWidth: 10, strokeColor: .orange)
        shapeLayer.strokeEnd = 0
        layer.addSublayer(shapeLayer)
    }
    
    private func createTrackLayer(center: CGPoint,
                                  radius: CGFloat,
                                  lineWidth: CGFloat,
                                  strokeColor: UIColor) -> CAShapeLayer {
        let circlePath = UIBezierPath(arcCenter: center,
                                      radius: radius,
                                      startAngle: -.pi / 2,
                                      endAngle: .pi * 3 / 2,
                                      clockwise: true)
        let layer = CAShapeLayer()
        layer.path = circlePath.cgPath
        layer.fillColor = UIColor.clear.cgColor
        layer.strokeColor = strokeColor.cgColor
        layer.lineWidth = lineWidth
        layer.lineCap = .round
        return layer
    }
    
    func updateValue(_ value: CGFloat) {
        let anim = CABasicAnimation(keyPath: "strokeEnd")
        guard let fromValue = shapeLayer.presentation()?.value(forKey: "strokeEnd") as? CGFloat else {
            return
        }
        anim.fromValue = fromValue
        anim.toValue = value
        anim.duration = 1
        anim.isRemovedOnCompletion = false
        anim.fillMode = .forwards
        shapeLayer.add(anim, forKey: "key")
    }
}