title: React Navigation modal height
body: <p>How do I set the height a <a href="https://reactnavigation.org" rel="noreferrer">React Navigation</a> modal view so once it has appeared it will only cover about half of the screen from the bottom up, and the view below remains visible? </p>
  
  <p><strong>Update:</strong> I'm trying to create a ux flow similar to the App Store purchase modal, where some kind of StackNavigator is nested in a modal that fills the bottom half of the screen.</p>
  
  <p><a href="https://i.stack.imgur.com/BAhTZl.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/BAhTZl.jpg" alt="App Store modal"></a></p>