A simple progress indicator Written in swiftUI

Spinner.swift

//
//  Spinner.swift
//  IHS-aafh
//
//  Created by Gustaf Nilklint on 2020-05-28.
//  Copyright © 2020 Gustaf Nilklint. All rights reserved.
//

import SwiftUI

struct Spinner: View {
    
    var color : Color
    
    @State private var fillPoint = 0.0
    @State private var colorIdx = 0
    @State private var rotation = 0.0
    
    private let duration = 1.2
    
    private var pathAnimation : Animation {
        Animation.easeOut(duration: duration).repeatForever(autoreverses: false)
    }
    
    private var rotationAnimation: Animation {
        Animation.linear(duration: 4.0)
            .repeatForever(autoreverses: false)
    }
    
    var body: some View {
        GeometryReader{ geo in
            Ring(fillPortion: self.fillPoint)
                .stroke(self.color.opacity(0.7), style: StrokeStyle(lineWidth: geo.size.width/12, lineCap: .round))
                .rotationEffect(.degrees(self.rotation))
                .onAppear() {
                    withAnimation(self.pathAnimation) {
                        self.fillPoint = 1.0
                    }
                    withAnimation(self.rotationAnimation, {
                        self.rotation = 360
                    })
            }
        }
    }
}

struct Ring : Shape {
    var fillPortion : Double
    var delayedPoint : Double = 0.55
    
    var animatableData: Double {
        get { return fillPortion }
        set{ fillPortion = newValue }
    }
    
    func path(in rect: CGRect) -> Path {
        var start : Double
        let end = (360 * fillPortion)
        
        if fillPortion > delayedPoint {
            start = (2 * fillPortion * 360)
        }else{
            start = 0
        }
        
        var path = Path()
        
        path.addArc(center: CGPoint(x: rect.midX, y: rect.midY),
                    radius: rect.width/2,
                    startAngle: .degrees(start),
                    endAngle: .degrees(end),
                    clockwise: false)
        return path
    }
}

struct SpinnerSampleView : View {
    @State var loading = false
    
    var body: some View {
        VStack {
            Button("Load", action: {
                withAnimation{
                    loading.toggle()
                }
            })
            HStack {
                Text("Loading")
                Spinner(color: .gray).frame(width: 50, height: 50)
            }.opacity(loading ? 1 : 0 )
            Spinner(color: .green).frame(width: 50, height: 50).opacity(loading ? 1 : 0 )
            if loading {
                Spinner(color: .blue).frame(width: 50, height: 50)
            }
            Spinner(color: .red).frame(width: 50, height: 50).opacity(loading ? 1 : 0 )
        }
    }
}


struct Spinner_Previews: PreviewProvider {
    static var previews: some View {
        SpinnerSampleView()
    }
}