title: Cannot convert value of type 'Binding<Double>' to expected argument type 'Binding<Double?>'
body: <p>Sometimes I want to pass a value into @Binding property, and sometimes I do not want.</p>
  
  <pre><code>struct ParentView: View {
      @State var prop = 0.0
  
      var body: some View {
          ChildView(prop: $prop) // Error: Cannot convert value of type 'Binding&lt;Double&gt;' to expected argument type 'Binding&lt;Double?&gt;'
          ChildView() // sometimes I do not want pass anything
      }
  }
  
  struct ChildView: View {
      @Binding var prop: Double?
  
      init(prop: Binding&lt;Double?&gt; = .constant(nil)) {
          _prop = prop
      }
  
      var body: some View {
          Text("Child View")
      }
  }
  </code></pre>
  
  <p>The solution may be following code.  </p>
  
  <pre><code>@State var prop: Double? = 0.0
  </code></pre>
  
  <p>But, if possible, I don't want to define @State property as an Optional type.<br>
  Is there any other way?</p>