Touch.swift

import PlaygroundSupport
import SwiftUI

extension View {
  public func offset(by offset: CGPoint) -> Self.Modified<_OffsetEffect> {
    self.offset(x: offset.x, y: offset.y)
  }
}

struct LiveView : View {
  
  @State var position: CGPoint = .zero
  
  var body: some View {
    ZStack {
      Circle()
        .foregroundColor(Color.black.opacity(0.1))
        .frame(width: 320, height: 320)
      
      Image(systemName:"asterisk.circle.fill")
        .scaleEffect(CGSize(width: 3, height: 3))
        .foregroundColor(Color.blue.opacity(0.5))
        .offset(by: self.position)
        .animation(.spring())
        .gesture(DragGesture()
          .onChanged {
            self.position = $0.location
          }
          .onEnded { _ in
            if sqrt(self.position.x * self.position.x + self.position.y * self.position.y) > 160 {
              self.position = CGPoint.zero
            }
          }
      )
    }
  }
}

PlaygroundPage.current.liveView = UIHostingController(rootView: LiveView())