title: React Native StackNavigator: Refresh data after goBack() Action
body: <p>I'm trying to re-render the first screen of the StackNavigator after saving the data for a new listItem. After a successful save, I call <code>this.props.navigation.dispatch(NavigationActions.back())</code>
  and I want to re-render the page with a a <code>this._updateData</code> function. I tried a solution mentioned here: <a href="https://github.com/react-navigation/react-navigation/issues/922" rel="nofollow noreferrer">https://github.com/react-navigation/react-navigation/issues/922</a> by beausmith where the <code>this._updateData</code> function gets passed to this.props.navigation.navigate like so:</p>
  
  <pre><code>this.props.navigation.navigate('ScreenB', {
    onNavigateBack: this._updateData
  })
  </code></pre>
  
  <p>And then  on ScreenB you would do this:</p>
  
  <pre><code>this.props.navigation.state.params.onNavigateBack()
  </code></pre>
  
  <p>And</p>
  
  <pre><code>this.props.navigation.dispatch(NavigationActions.back())
  </code></pre>
  
  <p>With a StackNavigator, you don't need to call this.props.navigation.navigate, as it is already built into the header. I tried adding <code>this._updateData</code> to <code>this.props.navigation.state.params</code> in the ComponentDidMount hook of screenA and then calling it as I had above in ScreenB but that didn't seem to do anything (No error message, but no refresh). Any idea where I'm going wrong?</p>