Adapt the demo app to run in Expo (instead of requiring native Android/iOS setup)

[zhibek]

No description provided.

[zhibek]

Following the changes in this PR, the application loads successfully in Expo and most features are working correctly.

Areas currently not functioning correctly are:

• Icons
• Fonts

[zhibek]

@xotahal Thanks for sharing your work on react-native-material-ui! I'm not sure if you're interested in adopting this PR to allow the demo app to use Expo. For me, it gave me a faster way to try the demo out and is an easy reference for the components that are available in react-native-material-ui.

[cepm-nate]

Regarding the Fonts: I've been able to load them into an expo project with Material Design by doing something like this for my main render() call:

  render() {
    return !this.state.resourcesLoaded 
    ? <AppLoading
        startAsync={this._cacheResourcesAsync}
        onFinish={() => this.setState({ resourcesLoaded: true })}
        onError={console.warn}
      /> 
    : <MainAppContainer />;
  }

And the cache loader is simply

_cacheResourcesAsync() {
  return Font.loadAsync({
    'Roboto': require('./res/fonts/Roboto-Regular.ttf'),
  });
}

(And yes, make sure you initialize the resourcesLoaded sate to false.)

This method could be extended to use multiple promises in the _cacheResourceAsync() to grab multiple fonts or other resources. Just an idea.

[DaniGuardiola]

Thank you so much! This works!! And it made my life so much easier! Seems pretty broken though, with a lot of the images not showing up and animations not working.

[paulolc]

The README should be updated with instructions on how to run in through Expo.