App.js

import React from 'react';
import { StyleSheet, Text, View } from 'react-native';
import {Asset} from 'expo-asset';
import {AppLoading} from 'expo';
import LoginPage from './app/index';
import CardClass from './app/dashboard'
import Example from './app/test'


function cacheImages(images) {
  return images.map(image => {
    if (typeof image === 'string') {
      return Image.prefetch(image);
    } else {
      return Asset.fromModule(image).downloadAsync();
    }
  });
} 
 
export default class App extends React.Component {
  constructor(){
    super();
    this.state = {
      isReady: false
    }
  }

  async _loadAssetsAsync() {
    const imageAssets = cacheImages([
      require('./assets/bg.jpg'),
    ]);

    await Promise.all([...imageAssets]);
  } 

  render() {
    if (!this.state.isReady) {
      return (
        <AppLoading
          startAsync={this._loadAssetsAsync}
          onFinish={() => this.setState({ isReady: true })}
          onError={console.warn}
        />
      );
  
      }
      return <CardClass/>
    }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});