Question

每次按一个按钮，进度条都会上升％20，但问题是例如，如果它在％80，我重新加载应用程序，它将显示为％60而不是，我想知道是否有人可以帮助我修复此问题，以便在重新加载或关闭应用程序后，进度条百分比保持不变。

'use strict';

var React = require('react-native');
var ProgressBar = require('react-native-progress-bar');

var {
  AppRegistry,
  AsyncStorage,
  StyleSheet,
  Text,
  View,
  TouchableHighlight
} = React;

var styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#FFF',
  },
  button: {
    alignSelf: 'center',
    marginTop: 50,
    width: 100,
    height: 50,
    backgroundColor: '#0059FF',
    borderRadius: 8,
    borderWidth: 2,
    borderColor: '#0059FF'
  },
  buttonClear: {
    alignSelf: 'center',
    marginTop: 10,
    width: 100,
    height: 50,
    backgroundColor: '#3B3A3A',
    borderRadius: 8,
    borderWidth: 2,
    borderColor: '#3B3A3A'
  },
  buttonText: {
    fontSize: 18,
    textAlign: 'center',
    lineHeight: 33,
    color: '#FFF',
  }
});

var PROGRESS = 0;

class BasicStorageExample extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      progress: PROGRESS
    }
  }

  componentDidMount() {
    AsyncStorage.getItem('progressbar')
      .then((value) => {
        JSON.parse(value);
        this.setState({
          progress: value 
        });
        console.log('Progress on load: ' + value);
      })
      .done();
  }

  onButtonPress() {
    AsyncStorage.setItem('progressbar', JSON.stringify(PROGRESS))
      .then(() => {
        JSON.parse(PROGRESS);
        this.setState({
          progress: PROGRESS += 0.2
        });
        console.log('Progress on Button Press: ' + PROGRESS);
      })
      .done();
  }

  onButtonClearPress() {
    AsyncStorage.setItem('progressbar', JSON.stringify(PROGRESS))
      .then(() => {
        JSON.parse(PROGRESS);
        PROGRESS = 0;
        this.setState({
          progress: 0
        });
      })
      .done();
  }

  render() {
    return (
      <View style={styles.container}>
        <ProgressBar
          fillStyle={{}}
          backgroundStyle={{backgroundColor: '#cccccc', borderRadius: 2}}
          style={{marginTop: 10, width: 300}}
          progress={this.state.progress} />
        <TouchableHighlight
          ref="button"
          style={styles.button}
          underlayColor='#002C7F'
          onPress={this.onButtonPress.bind(this)}>
          <Text style={styles.buttonText}>Done</Text>
        </TouchableHighlight>
        <TouchableHighlight
          style={styles.buttonClear}
          underlayColor='#002C7F'
          onPress={this.onButtonClearPress.bind(this)}>
          <Text style={styles.buttonText}>Clear</Text>
        </TouchableHighlight>
      </View>
    );
  }
};

AppRegistry.registerComponent('BasicStorageExample', () => BasicStorageExample);

Answer 1

问题是您获得了PROGRESS的旧值（在递增0.2之前）并将此值设置为项progressbar。

因此，每次重新加载时，React都会运行componentDidMount函数，并且因为您将progressbar设置为PROGRESS的旧值，它将始终显示它在视图中看到的一个增量后面

尝试将onButtonPress()更改为：

onButtonPress() {
    PROGRESS += 0.2;
    AsyncStorage.setItem('progressbar', JSON.stringify(PROGRESS))
    ... // continues normally

关闭应用后，React Native进度条百分比不保持不变

1 个答案: