title: react native 2 dropdown depend on first one
body: <p>I am trying to connect two dropdown with  in react native,
  same as country and city
  if i select any country it should load cities from that country to second drop-down 
  all data is in a external json file 
  but nothing is loading in both drop down (picker)</p>
  
  <p>json file : </p>
  
  <pre><code>{
    "interest": [
          {
              "RAW_MATERIAL":["abc","cde"]
          },
          {
              "OEM_PARTS":["xyz","qwer"]
          },
          {
             "CONSUMABLES":["poiu","fjgl"]
          },
          {
              "SERVICE":["xvcbv","qweiw"]
          }
      ],
  }
  </code></pre>
  
  <p>react native picker i use: </p>
  
  <pre><code>import React, { Component } from 'react';
  import { Container,Picker,Button } from 'native-base';
  
  const cData = require('../data.json');
  export default class Vendorsupplies extends Component {
  
    constructor(props) {
      super(props);
      this.state = {
        interest:'',
        interest2:''
      };
    }
  
  
   interest(value: string) {
      this.setState({
        interest: value
      });
    }
   interest2(value: string) {
      this.setState({
        interest2: value
      });
    }
  
  &lt;Picker
                note
                mode="dropdown"
                style={{ width: 120 }}
                selectedValue={this.state.interest}
                onValueChange={this.interest.bind(this)}
                name="intre"
              &gt;
              {cData.interest.map((number) =&gt;
    &lt;Picker.Item label={number.interest_in} value={number.interest_in} /&gt;
                        )} 
                &lt;/Picker&gt;
  
  &lt;Picker
                note
                mode="dropdown"
                style={{ width: 120 }}
                selectedValue={this.state.intre2.interest}
                onValueChange={this.intre2.interest.bind(this)}
                name="intre2"
              &gt;
              {cData.interest.map((number) =&gt;
    &lt;Picker.Item label={number.intre2.interest_in} value={number.intre2.interest_in} /&gt;
                        )} 
                &lt;/Picker&gt;
  </code></pre>