title: How to STOP Animation().repeatForever in SwiftUI
body: <p>In SwiftUI I am trying to start and STOP an animation with a button.  I can't find a method within SwiftUI that lets me stop an automation.  In Swift 4 I used to say "startButton.layer.removeAllAnimations()".  Is there an equivalent in SwiftUI?</p>
  
  <p>For the code below, how would I used the value of start to enable/disable the animation.  I tried .animation(start ? Animation(...) : .none) without any luck [creates some odd animation within the button].</p>
  
  <pre><code>import SwiftUI
  
  struct Repeating_WithDelay: View {
      @State private var start = false
  
      var body: some View {
          VStack(spacing: 20) {
              TitleText("Repeating")
              SubtitleText("Repeat With Delay")
              BannerText("You can add a delay between each repeat of the animation. You want to add the delay modifier BEFORE the repeat modifier.", backColor: .green)
  
              Spacer()
  
              Button("Start", action: { self.start.toggle() })
                  .font(.largeTitle)
                  .padding()
                  .foregroundColor(.white)
                  .background(RoundedRectangle(cornerRadius: 10).fill(Color.green))
                  .overlay(
                      RoundedRectangle(cornerRadius: 10)
                          .stroke(Color.green, lineWidth: 4)
                          .scaleEffect(start ? 2 : 0.9)
                          .opacity(start ? 0 : 1))
                  .animation(Animation.easeOut(duration: 0.6)
                      .delay(1) // Add 1 second between animations
                      .repeatForever(autoreverses: false))
  
              Spacer()
  
          }
          .font(.title)
      }
  }
  
  struct Repeating_WithDelay_Previews: PreviewProvider {
      static var previews: some View {
          Repeating_WithDelay()
      }
  }
  </code></pre>