title: SwiftUI: ForEach in Picker doesn't update
body: <p>I have an array of elements, from which I want to chose one using <code>Picker</code>, and I have a <code>Button</code>  which simply adds a new element to the array. The thing is, when I add an element, the <code>Picker</code> choices are not updated. It doesn't work with <code>DefaultPickerStyle</code>, but works with <code>SegmentedPickerStyle</code>.</p>
  
  <p>The code:</p>
  
  <pre class="lang-swift prettyprint-override"><code>import SwiftUI
  
  struct ExampleView: View {
      @State
      var array : Array&lt;Int&gt; = [Int]()
      @State
      var selection : Int = 0
  
      var body: some View {
          VStack {
              Picker("", selection: self.$selection) {
                  ForEach(self.array, id : \.self) { i in
                      Text(String(i))
                  }
              }
              // uncomment, and picker will refresh upon pushing the button
              //.pickerStyle(SegmentedPickerStyle())
  
              Button(action: {
                  self.array.append(self.array.count)
              }){
                  Text("Add me: " + String(self.array.count))
              }
          }
      }
  }
  
  struct ExampleView_Previews: PreviewProvider {
      static var previews: some View {
          ExampleView()
      }
  }
  </code></pre>
  
  <p>Is there any way to fix this? I really need to update the Picker (in its default styling). Xcode Version 11.2.1 (11B500).</p>