新建src/components/shared/Loading.js文件

import * as React from 'react';
import { StyleSheet, ActivityIndicator } from 'react-native';
import Colors from '../../constants/Colors';

const Loading = () => {
  return (
    <ActivityIndicator
      size="small"
      color={Colors.primary}
      style={styles.ActivityIndicatorStyle}
    />
  );
};

const styles = StyleSheet.create({
  ActivityIndicatorStyle: {
    flex: 1,
    backgroundColor: '#fff',
  },
});

export...