title: how to navigate to another screen in react native when fetch is done
body: <p>I'm new in React Native and trying create my first app. So I have a question:</p>
  
  <p>I got 2 screens (using react-navigation). At first screen there is a render of app logo with spinner(from native-base) and fetch to the server at the same time. And I need to navigate to another screen only when fetch is over and responce is handled. All I found at react-navigation docs is a solution with button, but it's not my case. Also I don't want to use ActivityIndicatorIOS (app should be correct for Android). </p>
  
  <p>Please help me understand what should I do? </p>
  
  <p>Thanks a lot!</p>