title: Setting a @State var from another view in SwiftUI
body: <p>I am trying to set the value of a <code>@State</code> var in var <code>a</code> of struct <code>A</code> from a var <code>b</code> of struct <code>B</code>, but it doesn't work.  I need to use a <code>@State</code> var because I am passing it as a binding.  Ex:</p>
  
  <pre><code>struct A : View {
    @State var myBindableVar = ""
    var body : some View {
       TextField(self.$myBindableVar) ...
    }
  }
  
  struct B : View {
    @State var a : A
    var body : some View {
       Button(action: { self.a.myBindableVar = "???" }) { ... }
    }
  }
  </code></pre>
  
  <p><code>myBindableVar</code> isn't set to <code>"???"</code> when the button is tapped.  Why?</p>