title: SwiftUI View Property willSet & didSet property observers not working
body: <p>I have a SwiftUI (Beta 5) view with an attached ViewModel. I want to navigate to it via a navigationLink and pass in a simple parameter (called FSAC in this case)</p>
  <p>I navigate using</p>
  <pre><code>NavigationLink(&quot;Next&quot;, destination: MyTestView(FSAC: &quot;testFsac&quot;))
  </code></pre>
  <p>The view has an FSAC Property with willSet and didSet property observer</p>
  <pre><code>struct MyTestView: View {
      @ObservedObject var vm = MyTestViewModel()
  
      var FSAC: String {
          willSet {
              print(&quot;will set fsac&quot;)
          }
          didSet {
              print(&quot;did set fsac&quot;)
              vm.FSAC = FSAC
          }
      }
          
      var body: some View {
          VStack {
              Text(&quot;FSAC: \(FSAC)&quot;)
              Text(&quot;VM FSAC: \(vm.FSAC)&quot;)
          }
      }
  }
  </code></pre>
  <p>The print statements are never called. The first text box displays the parameter correctly; the second is blank.</p>
  <p>How can I get the Property Observers to fire?</p>
  <p>More generally, is there a &quot;correct&quot; way to use a navigationLink to pass parameters to a View that has a ViewModel?</p>