Q:

Checkbox not rendering according to state value

I have to change the Checkbox UI from Check to Uncheck and vice versa according to the value of the state : checked.
For that I have used 'react-native-elements'.
My state name is checked
I have also taken two Buttons to change the state value, but the checkbox is not rendering according to value of the state.
I have done as below : Please guide. 
Thanks.

import React, {Component} from 'react';
import {Platform, StyleSheet, Text, View,Button,Alert} from 'react-native';
import { CheckBox } from 'react-native-elements'

export default class App extends Component {
  constructor (props) {
    super(props)
    this.state = {
      checked: true,
    }
 }

render() {
    return (
      <View style={styles.container}>

<CheckBox
  title='Click Here'
  checked={this.state.checked}
/>

<CheckBox
  center
  title='Click Here'
  checked={this.state.checked}
/>

  <Button value="Check"
       title="Check"
          onPress={()=>{
            this.state.checked=true;
            Alert.alert("State >>"+this.state.checked);
          }}
       />

       <Button value="Un-Check"
       title="Un-Check"
          onPress={()=>{
            this.state.checked=false;
            Alert.alert("State >"+this.state.checked);
          }}
          />
      </View>
    );
  }
}

EDIT 
I have done as below : 
<Button value="Check"
       title="Check"
          onPress={()=>{

            this.setState((prevState,props)=>({
              isChecked=prevState.isChecked
            }));
            //this.state.isChecked=true;
            Alert.alert("State >>"+this.state.isChecked);
          }}
       />

But, It gives me syntax error : 
Unexpected Token (81:23)

A:

replace 
 this.state.isChecked=true;

with 
 this.setState({
    isChecked : true
   })

You can not assign value directly to the state for that you have to use setState({})  so update you state as mentioned above 
for false use 
 this.setState({
        isChecked : false
       })

For EDIT  section
  this.setState((prevState,props)=>({
          isChecked : prevState.isChecked
        }));

Use : inside stae  do not use =  it will give sintext error..

