React Native - ActivityIndicator

在本章中，我们将向您展示如何在 React Native 中使用活动指示器。

步骤 1：应用

应用组件将用于导入并展示我们的 ActivityIndicator。

App.js

import React from 'react'
import ActivityIndicatorExample from './activity_indicator_example.js'

const Home = () => {
   return (
      <ActivityIndicatorExample />
   )
}
export default Home

步骤 2：ActivityIndicatorExample

Animating 属性是一个用于展示活动指示器的布尔值。后者会在组件挂载后六秒关闭。这是使用 closeActivityIndicator() 函数完成的。

activity_indicator_example.js

import React, { Component } from 'react';
import { ActivityIndicator, View, Text, TouchableOpacity, StyleSheet } from 'react-native';

class ActivityIndicatorExample extends Component {
   state = { animating: true }
   
   closeActivityIndicator = () => setTimeout(() => this.setState({
   animating: false }), 60000)
   
   componentDidMount = () => this.closeActivityIndicator()
   render() {
      const animating = this.state.animating
      return (
         <View style = {styles.container}>
            <ActivityIndicator
               animating = {animating}
               color = '#bc2b78'
               size = "large"
               style = {styles.activityIndicator}/>
         </View>
      )
   }
}
export default ActivityIndicatorExample

const styles = StyleSheet.create ({
   container: {
      flex: 1,
      justifyContent: 'center',
      alignItems: 'center',
      marginTop: 70
   },
   activityIndicator: {
      flex: 1,
      justifyContent: 'center',
      alignItems: 'center',
      height: 80
   }
})

当我们运行该应用时，我们会在屏幕上看到加载器。它会在六秒后消失。