react-native
RefreshControl con ListView

Osservazioni

Aggiorna controllo

  _refreshControl(){
    return (
      <RefreshControl
        refreshing={this.state.refreshing}
        onRefresh={()=>this._refreshListView()} />
    )
  }

rinfrescante: è lo stato dello spinner (vero, falso).

onRefresh: questa funzione verrà richiamata quando si aggiorna ListView / ScrollView.

Esempio di funzione onRefresh

  _refreshListView(){
    //Start Rendering Spinner
    this.setState({refreshing:true})
    this.state.cars.push(
      {name:'Fusion',color:'Black'},
      {name:'Yaris',color:'Blue'}
    )
    //Updating the dataSource with new data
    this.setState({ dataSource:
        this.state.dataSource.cloneWithRows(this.state.cars) })
    this.setState({refreshing:false}) //Stop Rendering Spinner
  }

qui stiamo aggiornando la matrice e successivamente aggiorneremo il data source. possiamo usare fetch per richiedere qualcosa dal server e usare async / await.

Aggiorna controllo con ListView Esempio completo

RefreshControl viene utilizzato all'interno di ScrollView o ListView per aggiungere funzionalità pull a refresh. in questo esempio lo useremo con ListView

'use strict'
import React, { Component } from 'react';
import { StyleSheet, View, ListView, RefreshControl, Text } from 'react-native'


class RefreshControlExample extends Component {
  constructor () {
    super()
    this.state = {
      refreshing: false,
      dataSource: new ListView.DataSource({
        rowHasChanged: (row1, row2) => row1 !== row2 }),
      cars : [
        {name:'Datsun',color:'White'},
        {name:'Camry',color:'Green'}
      ]
    }
  }

   componentWillMount(){
     this.setState({ dataSource:
       this.state.dataSource.cloneWithRows(this.state.cars) })
   }

  render() {
    return (
      <View style={{flex:1}}>
        <ListView
          refreshControl={this._refreshControl()}
          dataSource={this.state.dataSource}
          renderRow={(car) => this._renderListView(car)}>
        </ListView>
      </View>
    )
  }

  _renderListView(car){
    return(
      <View style={styles.listView}>
        <Text>{car.name}</Text>
        <Text>{car.color}</Text>
      </View>
    )
  }

  _refreshControl(){
    return (
      <RefreshControl
        refreshing={this.state.refreshing}
        onRefresh={()=>this._refreshListView()} />
    )
  }

  _refreshListView(){
    //Start Rendering Spinner
    this.setState({refreshing:true})
    this.state.cars.push(
      {name:'Fusion',color:'Black'},
      {name:'Yaris',color:'Blue'}
    )
    //Updating the dataSource with new data
    this.setState({ dataSource:
        this.state.dataSource.cloneWithRows(this.state.cars) })
    this.setState({refreshing:false}) //Stop Rendering Spinner
  }

}

const styles = StyleSheet.create({

  listView: {
    flex: 1,
    backgroundColor:'#fff',
    marginTop:10,
    marginRight:10,
    marginLeft:10,
    padding:10,
    borderWidth:.5,
    borderColor:'#dddddd',
    height:70
  }

})

module.exports = RefreshControlExample