2019-12-02

import React, { Component } from 'react';
import {
  Text,
  View,
  Button
} from 'react-native';
class B extends Component {
  state = {
    nub: 0
  }
  renderItem = ()=> {
    return {this.state.nub}
  }
  componentDidMount(){
    this.props.forceUpdate()
  }
  render() {
    return (
      
        B
        {
          this.setState({
            nub: this.state.nub+1
          },()=>{
            this.props.forceUpdate()
          })
        }}/>
        {this.props.element(this.renderItem)}
      
    );
  }
}
class App extends Component {
  element = (item) => {
    this.renderElement = ()=> item()
  }
  renderElement = () => {
    return null
  }
  
  render() {
    return (
      
        
          A
          
        
          
          {this.renderElement()}
          {this.renderElement()}
          {this.renderElement()}
        
      
    );
  }
}

export default App;