title: How to show loading progress or spinner in the middle of the screen with React Native?
body: <p>I am developing React Native app.</p>
  
  <p>I was able to solve all problems by myself but this is exception.
  I am going to load another screen with bottom tab navigator.</p>
  
  <p>For example, after user login to the app, it should show main home screen which has many pictures and many style sheet effects, icons. Because of that, after login confirm ( I mean after alert of the login confirm), the main home screen appears after a few seconds.</p>
  
  <p>So I want to show some spinner in the login screen while loading main home screen in the background and when it is ready to show, erase spinner and show main home screen.
  How can I do this?</p>
  
  <p>My bottom tab navigator was simply created with <code>createBottomTabNavigator()</code> method.</p>