React native 在react native中从后台模式返回时更新数据

嗨，我在react native中使用地理位置坐标来显示我周围的用户。我已经实现了一个下拉刷新功能，可以在我改变位置后刷新用户列表。当我从后台模式返回时，如何刷新数据

  displayPosition = () => {
      this.watchId = Geolocation.getCurrentPosition(
        (position) => {
          let obj = {
            latitude: position.coords.latitude,
            longitude: position.coords.longitude,
            error: null
          }
          this.setState(obj);
        },
        (error) => this.setState({ error: error.message }),
        { enableHighAccuracy: true, timeout: 200000, maximumAge: 1000},
      );
      if(this.state.latitude!=null){
        this.getData();
      }else{
        setTimeout(this.displayPosition.bind(this),200)
      }
      //console.log(this.state.latitude);
      //console.log(this.state.longitude);
  }

  handleRefresh = () => {
    this.setState (
      {
        refreshing: true,
      },
      () => {
        this.setState({refreshing: false});
        this.displayPosition();
        //this.getData();
      }
    );
  };


  componentDidMount() {
    this.displayPosition();
    //this.getData();
    this.props.navigation.setParams({ refresh: this._handleRefresh });
  }

  componentWillUnmount() {
    Geolocation.clearWatch(this.watchId);
  }

谢谢

您可以在react native中为相同的应用程序添加侦听器

对于同一个列表，共有4个列表器

willFocus-屏幕将聚焦 didFocus-屏幕聚焦如果有转换，则转换完成 willBlur-屏幕将不聚焦 didBlur-屏幕未聚焦如果有过渡，则过渡完成 请尝试下面的代码

componentWillMount(){
    const didFocusSubscription = this.props.navigation.addListener(
      'didFocus',
      payload => {
        console.warn('didFocus ', payload);
        # just write your code/call a method here which you want to execute when the app comes from background
        this.handleRefresh()
      }
    );
}

完成后别忘了取下它

componentWillUnmount(){
    didFocusSubscription.remove();
}

你能读的更多。谢谢：

您可以在react native中为相同内容添加侦听器

对于同一个列表，共有4个列表器

willFocus-屏幕将聚焦 didFocus-屏幕聚焦如果有转换，则转换完成 willBlur-屏幕将不聚焦 didBlur-屏幕未聚焦如果有过渡，则过渡完成 请尝试下面的代码

componentWillMount(){
    const didFocusSubscription = this.props.navigation.addListener(
      'didFocus',
      payload => {
        console.warn('didFocus ', payload);
        # just write your code/call a method here which you want to execute when the app comes from background
        this.handleRefresh()
      }
    );
}

完成后别忘了取下它

componentWillUnmount(){
    didFocusSubscription.remove();
}

你能读的更多。谢谢: