async-await - React Native 等待 AsyncStorage 获取值

Question

这是一个常见问题，React Native 试图在从 AsyncStorage 获取值之前进行渲染。我已经在几个地方看到了解决方案，但由于某种原因，它对我来说根本不起作用。也许是因为我使用的是 React Native 25.1？它只是无限期地卡在“正在加载...”上。如果我在渲染上运行控制台日志以显示 isLoading(没有 if 方法)，它将返回 false然后 true所以理论上它应该可以工作。但是使用 if方法使其永远停留在“加载”上，并且日志仅返回错误。

import React, { Component } from 'react';

import {
  Text,
  View,
  AsyncStorage
} from 'react-native';

  class MainPage extends Component {
   constructor(props: Object): void {
   super();
   this.state = {
     isLoading: false,
   };
 }

  componentWillMount() {
    AsyncStorage.getItem('accessToken').then((token) => {
      this.setState({
        isLoading: false
      });
    });
  }

  render() {
    if (this.state.isLoading) {
      return <View><Text>Loading...</Text></View>;
    }
    // this is the content you want to show after the promise has resolved
    return <View/>;
  }

});

Answer 1

嘿试试这个...

import React, { Component } from 'react';

import {
  Text,
  View,
  AsyncStorage
} from 'react-native';

class MainPage extends Component {

   constructor(props: Object): void {
       super(props);
       this.state = {
         isLoading: false,
       };
   }

  componentWillMount() {
    AsyncStorage.getItem('accessToken').then((token) => {
      this.setState({
        isLoading: false
      });
    });
  }

  render() {
    if (this.state.isLoading) {
      return <View><Text>Loading...</Text></View>;
    }
    // this is the content you want to show after the promise has resolved
    return <View/>;
  }
}

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