CustomLoadingAnimation.swift

import SwiftUI

struct ContentView: View {
    @State var theta: Double = 0
    let radius: Double = 60
    let colors: [Color] = [.purple, .red, .yellow, .blue, .green]

    var body: some View {
        ZStack {
            ForEach(Array(colors.enumerated()), id: \.offset) { offset, style in
                let offset = Double(offset) * (2 * .pi) / Double(colors.count)
                ForEach([false, true], id: \.self) { reverse in
                    Dot(radius: radius, theta: theta, offset: offset, style: style, reverse: reverse)
                }
            }
        }
        .task {
            withAnimation(.linear(duration: 2).repeatForever(autoreverses: false)) {
                theta = 2 * .pi
            }
        }
    }
}

struct Dot: View, Animatable {
    var radius, theta, offset: Double
    var style: Color
    var reverse = false
    var animatableData: Double { get { theta } set { theta = newValue } }
    var body: some View {
        let theta = reverse ? -(theta + .pi) : theta
        let scale = 0.5 + (abs((theta - .pi).remainder(dividingBy: 2 * .pi)))/(2 * .pi)
        Circle()
            .frame(width: 30)
            .scaleEffect(x: scale, y: scale)
            .offset(
                x: radius * (cos(theta + offset) + cos(offset)),
                y: radius * (sin(theta + offset) + sin(offset))
            )
            .foregroundStyle(style)
            .rotationEffect(reverse ? .radians(.pi) : .zero)
            .shadow(color: style.opacity(0.3), radius: 10, y: 30 * scale)
    }
}

#Preview {
    ContentView()
}