a SwiftUI recreation of an interesting animation by @beesandbombs

RotatorView.swift

//
//  RotatorView.swift
//
//  Created by Pavel Zak on 16/11/2020.
//  original idea by: https://twitter.com/beesandbombs/status/1326312738033983489?s=20
//

import SwiftUI

func pow(_ x: Int, _ y: Int) -> Int {
  var result = 1
  for _ in 0..<y {
    result *= x
  }
  return result
}

struct RotatorShape: Shape {
    static let maxDivision: Int = 6
    var division: Int
        
    func path(in rect: CGRect) -> Path {
        return Path { path in
            let width = rect.width
            let height = rect.height
            
            let segments = 3*pow(2, division-1)
            let wx = width*0.5/CGFloat(Self.maxDivision)
            let wy = height*0.5/CGFloat(Self.maxDivision)
            
            for index in 0..<segments {
                
                
                let angle = 2*CGFloat.pi/CGFloat(segments)*CGFloat(index)
                
                path.move(to: CGPoint(x: width/2 + cos(angle)*wx*CGFloat(division), y: height/2 + sin(angle)*wy*CGFloat(division)))
                path.addLine(to: CGPoint(x: width/2 + cos(angle)*wx*CGFloat(division+1), y: height/2 + sin(angle)*wy*CGFloat(division+1)))
            }
        }
    }
}

struct CompassView: View {
    @State var angleStep: Double = 0
    
    func delayForDivision(_ division: Int) -> Double{
        return Double(division)*0.1
    }
    
    func angleForDivision(_ division: Int) -> Double{
        let segments = 3*pow(2, division-1)
        let baseAngle = 2*Double.pi/Double(segments)
        return baseAngle*angleStep
    }
    
    func animate (){
        withAnimation() {
            self.angleStep += 1.0
        }
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 2.0) {
            self.animate()
        }
    }
    
    var body: some View {
        let animation = Animation.easeInOut(duration: 1.0)
        return ZStack {
            ForEach (1 ..< RotatorShape.maxDivision+1) { division in
                RotatorShape(division: division)
                    .stroke(Color.red, lineWidth: 2.0)
                    .blendMode(.plusLighter)
                    .rotationEffect(Angle(radians: angleForDivision(division)))
                    .animation(animation.delay(delayForDivision(division)))
                RotatorShape(division: division)
                    .stroke(Color.green, lineWidth: 2.0)
                    .blendMode(.plusLighter)
                    .rotationEffect(Angle(radians: angleForDivision(division)))
                    .animation(animation.delay(delayForDivision(division)+Double(division)*0.015))
                RotatorShape(division: division)
                    .stroke(Color.blue, lineWidth: 2.0)
                    .blendMode(.plusLighter)
                    .rotationEffect(Angle(radians: angleForDivision(division)))
                    .animation(animation.delay(delayForDivision(division)+Double(division)*0.03))
            }
        }
        .onAppear() {
            withAnimation() {
                self.animate()
            }
        }
    }
}

struct RotatorView: View {
    var body: some View {
        CompassView()
            .frame(width: 300, height: 300)
    }
}