SwiftUI - Simple example of a radial menu. Just helping someone on Reddit. Not production code.

20200616-RadialMenuDemo_AR.playground

import SwiftUI
import PlaygroundSupport

struct ContentView: View {
  @GestureState private var showOverlay: Bool = false
  @GestureState private var longDrag: CGPoint = .zero
  @State private var currentButtonColorIndex: Array<Color>.Index = 0
  @State private var newButtonColorIndex: Array<Color>.Index? = nil
  
  private var currentButtonColor: Color {
    colors[currentButtonColorIndex]
  }
  private let colors: [Color] = [Color.blue, Color.red, Color.green, Color.yellow]
  private static let menuButtonSize: CGSize = .init(width: 100, height: 100)
  private let radialMenuSize: CGSize = .init(width: 125, height: 125)
    
  var body: some View {
    VStack {
      Spacer()
      Text("Current Location:")
      Text(longDrag == .zero ? " " : String(format: "%.2f", longDrag.x) + ", " + String(format: "%.2f", longDrag.y))
        .fixedSize()
        .padding(.bottom, 50)
      Circle()
        .fill(colors[newButtonColorIndex ?? currentButtonColorIndex])
        .colorMultiply(showOverlay || longDrag != .zero ? colors[newButtonColorIndex ?? currentButtonColorIndex]: .white)
        .frame(width: Self.menuButtonSize.width, height: Self.menuButtonSize.height)
        .overlay(
          Text("Menu")
            .bold()
            .animation(nil)
            .foregroundColor(.white)
        )
        .shadow(color: Color(UIColor.black.withAlphaComponent(showOverlay || longDrag != .zero ? 0.8 : 0.3)), radius: showOverlay || longDrag != .zero ? 2 : 4)
        .scaleEffect(showOverlay || longDrag != .zero ? 0.95 : 1)
        .animation(Animation.spring().speed(4))
        .gesture(
          LongPressGesture(minimumDuration: 0.1, maximumDistance: .infinity)
            .sequenced(before: LongPressGesture(minimumDuration: .infinity))
            .updating($showOverlay, body: { (value, state, _) in
              
              switch value {
              case .second(true, nil):
                state = true
              default:
                break
              }
            })
        )
        .simultaneousGesture(
          DragGesture(minimumDistance: 0.1, coordinateSpace: .local)
            .updating($longDrag, body: { (value, state, _) in
              state = value.location
            })
            .onChanged({
              let dist = $0.location.distance(to: CGPoint(x: Self.menuButtonSize.width / 2, y: Self.menuButtonSize.height / 2))
              guard dist >= (Self.menuButtonSize.width / 2) * 0.95 else {
                self.newButtonColorIndex = self.currentButtonColorIndex
                return
              }
              self.checkIfTouchEndedOnButton(location: $0.location, finalTouch: false)
            })
            .onEnded({ (val) in
              self.newButtonColorIndex = nil
              let dist = val.location.distance(to: CGPoint(x: Self.menuButtonSize.width / 2, y: Self.menuButtonSize.height / 2))
              guard dist >= (Self.menuButtonSize.width / 2) * 0.95 else {
                
                return
              }
              self.checkIfTouchEndedOnButton(location: val.location, finalTouch: true)
            })
        )
        .overlay(
          RadialMenuView(isShowing: Binding<Bool>(get: {
            self.showOverlay || self.longDrag != .zero
          }, set: {_ in }), radialMenuSize: radialMenuSize, colors: colors)
            .opacity(showOverlay || longDrag != .zero ? 1 : 0)
            .transition(.scale)
            .animation(.easeOut(duration: 0.3))
        )
      Spacer()
    }
  }
  
  func checkIfTouchEndedOnButton(location: CGPoint, finalTouch: Bool) {
    func changeColor(index idx: Int) {
      if finalTouch {
        if currentButtonColorIndex != idx {
          print("FINAL - menu item \(idx) selected with color \(colors[idx]) at location \(location)")
          currentButtonColorIndex = idx
        }
      }else {
        if newButtonColorIndex != idx {
          print("\(colors[idx]) menu item highlighted at location \(location)")
          newButtonColorIndex = idx
        }
      }
    }
    
    let mid = CGPoint(x: Self.menuButtonSize.width / 2, y: Self.menuButtonSize.height / 2)
    
    //Note: this will ONLY work with 4 colors / menu items. Just a demo.
    
    switch location.x {
    case mid.x...:
      if location.y > mid.y {
        changeColor(index: 0)
      }else if location.y < mid.y {
        changeColor(index: 3)
      }
    case ..<mid.x:
      if location.y > mid.y {
        changeColor(index: 1)
      }else if location.y < mid.y {
        changeColor(index: 2)
      }
    default:
      break
    }
  }
}

struct RadialMenuView: View {
  @Binding var isShowing: Bool
  let radialMenuSize: CGSize
  let colors: [Color]
    
  var body: some View {
    ZStack {
      ForEach(colors.indices, id: \.self) { idx in
        self.labelForButton(at: idx)
          .hueRotation(.degrees(self.isShowing ? 0 : -45))
          .rotationEffect(.degrees(self.isShowing ? 0 : 90))
      }
    }
  }
  
  func labelForButton(at idx: Int) -> some View {
    Circle()
      .trim(
        from: isShowing ? (CGFloat(idx + 1) * 0.25) - 0.25 : (CGFloat(idx + 1) * 0.25),
        to: CGFloat(idx + 1) * 0.25
      )
      .stroke(colors[idx], lineWidth: 30)
      .frame(width: radialMenuSize.width, height: radialMenuSize.height)
  }
}

fileprivate
extension CGPoint {
  func distanceSquared(to: CGPoint) -> CGFloat {
    CGFloat((self.x - to.x).magnitudeSquared) + CGFloat(((self.y - to.y).magnitudeSquared))
  }

  func distance(to: CGPoint) -> CGFloat {
    sqrt(distanceSquared(to: to))
  }
}

PlaygroundPage.current.setLiveView(ContentView())

GIF