Example ActivityIndicator

import React, { Component } from 'react'
import {
  View,
  ActivityIndicator,
  Button,
} from 'react-native'

export class App extends Component {
  state = { loading: false }

  activate = () => this.setState({ loading: true })

  render() {
    const { loading } = this.state

    return (
      <View>
        <ActivityIndicator
          size='large'
          color='#ff0000'
          animating={loading}
        />
        <Button
          title='Click me'
          onPress={this.activate}
        />
      </View>
    )
  }
}

export default App