Custom Toggle SwiftUI View with Haptic Touch-like gesture

HapticTouchToggle.swift

//
//  HapticTouchToggle.swift
//  Created by @shengchalover  on 15.12.2019.
//  License: MIT
//  Gesture mechanics inspired by DraggableCover from MovieSwift by Thomas Ricouard _ 19/06/2019 Apache License 2.0

import SwiftUI

///pass c as root view to UIHostingController in SceneDelegate
let c = HapticTouchToggle()

struct HapticTouchToggle: View {
    enum LongPressState { case inactive, pressing, haptic }
    private let hapticFeedback = UIImpactFeedbackGenerator(style: .heavy)
    init() { self.hapticFeedback.prepare() }

    @State private var flashLightOn = false
    @GestureState private var longPressState: LongPressState = .inactive
    var body: some View {
        // MARK: - gesture
        let hapticTouch = LongPressGesture(minimumDuration: 0.15).sequenced(before: DragGesture(minimumDistance: .leastNormalMagnitude))
            .updating($longPressState) { value, state, _ in
                switch value {
                    //long press recognized
                    case .first(true): state = .pressing
                    //longpress ended, drag has not begun. If disabled, behavior resembles springboard haptic ptress
                    case .second(true, nil): state = .pressing
                    //longpress ended, drag has begun.
                    case .second(true, /*let dragValue*/ _):
                        //fires only once in a gesture session;
                        if state != .haptic {
                            //async prevents runtime error; seems like safe workaround (https://swiftui-lab.com/state-changes/)
                            DispatchQueue.main.async {
                                self.flashLightOn.toggle()
                                self.hapticFeedback.impactOccurred(intensity: 1.0)
                            }
                            state = .haptic
                    }
                    default: state = .inactive
                }
        }
        .onEnded { _ in self.hapticFeedback.impactOccurred(intensity: 0.8) }
        // MARK: - view
        return FlashlightToggle.gesture(hapticTouch)
    }
    // MARK: -  main view
    private var FlashlightToggle: some View {
        ZStack(alignment: .center) {
            Circle()
                .foregroundColor(.init(.secondarySystemBackground))
                .opacity(0.9)
            FlashLightImage
        }
        .scaleEffect(hapticScale)
        .frame(width: 85, height: 85)
        .animation(.interpolatingSpring(mass: 1, stiffness: 150, damping: 15, initialVelocity: 5))
    }
    // MARK: - supporting view
    private var FlashLightImage: some View {
        flashLightOn ?
            Image(systemName: "flashlight.on.fill")
                .font(.system(size: 100))
                .scaleEffect(0.35)
            :
            Image(systemName: "flashlight.off.fill")
                .font(.system(size: 100))
                .scaleEffect(0.35)
    }
    // MARK: -   dynamic view parameters
    private var hapticScale: CGFloat { isBeingPressed ? (hasHapticTouchOccured ? 1.5 : 1.2) : 1.0 }
    private var isBeingPressed: Bool { hapticTouchState.0 ? true : false }
    private var hasHapticTouchOccured: Bool { hapticTouchState.1 ? true : false }
    private var hapticTouchState: (pressing: Bool, hapticTouch: Bool) {
        let pressing            = (pressing: true, hapticTouch: false)
        let pressingWithHaptic  = (pressing: true, hapticTouch: true)
        let notPressing         = (pressing: false, hapticTouch: false)
        switch self.longPressState {
            case .pressing: return pressing
            case .haptic: return pressingWithHaptic
            case .inactive:  return notPressing
        }
    }
    // MARK: -
}

struct HapticTouchButton_Previews: PreviewProvider {
    static var previews: some View {
        HapticTouchToggle()
    }
}

probably quite fragile and outdated