Demo showing animating concentric arcs on a timer without pulsing with the timer duration

ConcentricArcsDemo.swift

//
//  ConcentricArcsDemo.swift
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
//  of the Software, and to permit persons to whom the Software is furnished to do so,
//  subject to the following conditions:

//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
//  INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
//  PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
//  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
//  AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
//  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//  Created by Adam Fordyce on 23/01/2020.
//  Copyright © 2020 Adam Fordyce. All rights reserved.
//

import SwiftUI
import PureSwiftUI

let radiusStep: CGFloat = 100

struct ConcentricArcsDemo: View {
    
    func radius(_ index: Int) -> CGFloat {
        (radiusStep * 0.9 * index).asCGFloat
    }
    
    var body: some View {
        ZStack {
            ForEach(0..<11) { index in
                ArcView(lineWidth: radiusStep / 2)
                    .frame(self.radius(index))
            }
        }
    }
}

private struct ArcView: View {

    let lineWidth: CGFloat
    
    @State private var startAngle = randomStart()
    @State private var arcLength = randomArcLength()
    
    static func randomStart() -> Angle {
        360.random().degrees
    }
    
    static func randomArcLength() -> Angle {
        ((45...360).randomElement() ?? 0).degrees
    }
    
    var body: some View {
        ZStack {
            AnimatableArc(startAngle: self.startAngle, endAngle: self.startAngle + self.arcLength, clockwise: true)
                .strokeColor(.gray, lineWidth: self.lineWidth)
                .blur(15)
                .blendMode(.multiply)
            AnimatableArc(startAngle: self.startAngle, endAngle: self.startAngle + self.arcLength, clockwise: true)
                .strokeColor(.green, lineWidth: self.lineWidth)
                .hueRotation(360.random().degrees)
        }
        .onAppear {
            every(2) { timer in
                withAnimation(Animation.easeInOut(duration: 4).delay(1.0.random())) {
                    self.randomize()
                }
            }
        }
    }
    
    func randomize() {
        self.startAngle = Self.randomStart()
        self.arcLength = Self.randomArcLength()
    }
}

private struct AnimatableArc: InsettableShape {
    
    var startAngle: Angle
    var endAngle: Angle
    var clockwise: Bool
    var insetAmount: CGFloat = 0
    
    public var animatableData: AnimatablePair<Double, Double> {
        get {
            return AnimatablePair(startAngle.degrees, endAngle.degrees)
        }
        set {
            self.startAngle = newValue.first.degrees
            self.endAngle = newValue.second.degrees
        }
    }
    
    public func path(in rect: CGRect) -> Path {
            var path = Path()
        path.arc(center: CGPoint(rect.midX, rect.midY), radius: rect.width / 2 - insetAmount, startAngle: startAngle, endAngle: endAngle, clockwise: clockwise)
        return path
    }
    
    public func inset(by amount: CGFloat) -> some InsettableShape {
        AnimatableArc(startAngle: startAngle, endAngle: endAngle, clockwise: clockwise, insetAmount: insetAmount + amount)
    }
}

struct ConcentricArcsDemo_Previews: PreviewProvider {
    struct ConcentricArcsDemo_Harness: View {

        var body: some View {
            ConcentricArcsDemo()
        }
    }

    static var previews: some View {
        ConcentricArcsDemo_Harness()
    }
}

Nice animation technique!

Nice animation technique!

Thank you