title: Disable drag to dismiss in SwiftUI Modal
body: <p>I've presented a modal view but I would like the user to go through some steps before it can be dismissed.
  Currently the view can be dragged to dismiss. </p>
  
  <p>Is there a way to stop this from being possible?</p>
  
  <p>I've watched the WWDC Session videos and they mention it but I can't seem to put my finger on the exact code I'd need.</p>
  
  <pre class="lang-swift prettyprint-override"><code>struct OnboardingView2 : View {
  
      @Binding
      var dismissFlag: Bool
  
      var body: some View {
  
          VStack {
              Text("Onboarding here! ")
              Button(action: {
                  self.dismissFlag.toggle()
              }) {
                  Text("Dismiss")
              }
          }
      }
  }
  </code></pre>
  
  <p>I currently have some text and a button I'm going to use at a later date to dismiss the view.</p>