ActivityIndicator.swift

//
//  Spinner.swift
//  spinner
//
//  Created by Soroush Khanlou on 5/29/20.
//  Copyright © 2020 Soroush Khanlou. All rights reserved.
//

import SwiftUI

struct ActivityIndicator: View {

    @State var isAnimating = false

    var animationDuration: Double = 1.2

    private var pillCount = 12

    var body: some View {
        GeometryReader { geometry in
            ZStack {
                ForEach(0..<self.pillCount) { i in
                    Capsule()
                        .rotation(Angle(degrees: Double(30 * i)), anchor: UnitPoint(x: 0.5, y: 2))
                        .frame(width: geometry.size.width/18, height: geometry.size.width/5, alignment: .top)
                        .foregroundColor(Color(white: 0.5))
                        .opacity(self.isAnimating ? 0.1 : 1)
                        .offset(y: -geometry.size.height/3)
                        .animation(
                            Animation
                                .easeOut(duration: self.animationDuration)
                                .repeatForever(autoreverses: false)
                                .delay(Double(i) * self.animationDuration / Double(self.pillCount) - self.animationDuration)
                    )
                }
            }
        }
        .onAppear {
            self.isAnimating = true
        }
    }
}

struct ActivityIndicator_Previews: PreviewProvider {
    static var previews: some View {
        ActivityIndicator()
            .frame(width: 100, height: 100)
            .border(Color.blue)
    }
}