I am learning React Native now and recently I received the log message below.
Warning: componentWillMount is deprecated and will be removed in the next major version. Use componentDidMount instead. As a temporary workaround, you can rename to UNSAFE_componentWillMount.
I am doing this tutorial "React Native Tutorial: Building Android Apps with JavaScript" https://www.raywenderlich.com/178012/react-native-tutorial-building-android-apps-javascript
What should I do to remove the message?
I installed react-native-cli and did react-native init projectName. I changed package.json. I changed "react": "^16.3.0-alpha.1" to "^16.2.0" and then I did npm install.
My package.json
{ "name": "PropertyFinder", "version": "0.0.1", "private": true, "scripts": { "start": "node node_modules/react-native/local-cli/cli.js start", "test": "jest" }, "dependencies": { "react": "^16.2.0", "react-native": "0.54.0", "react-navigation": "^1.3.0" }, "devDependencies": { "babel-jest": "22.4.1", "babel-preset-react-native": "4.0.0", "jest": "22.4.2", "react-test-renderer": "^16.2.0" }, "jest": { "preset": "react-native" } }
But still show that warning.
SearchPage.js

'use strict';

import React, { Component } from 'react';
import {
  StyleSheet,
  Text,
  TextInput,
  View,
  Button,
  ActivityIndicator,
  Image
} from 'react-native';
// import { StackNavigator } from 'react-navigation';

export default class SearchPage extends Component<{}> {
  static navigationOptions = {
    title: 'Property Finder',
  };

  constructor(props) {
    super(props);
    this.state = {
      searchString: 'london'
    };
  }

  _onSearchTextChanged = (event) => {
    console.log('_onSearchTextChanged');
    this.setState({
      searchString: event.nativeEvent.text
    });
    console.log('Current: ' + this.state.searchString + ', Next: ' + event.nativeEvent.text);
  }

  render() {
    console.log('SearchPage render');

    return (
      <View style={styles.container}>
        <Text style={styles.description}>
          Search for houses to buy!
        </Text>      
        <Text style={styles.description}>
          Search by place-name or postcode.
        </Text>
        <View style={styles.flowRight}>
          <TextInput
            underlineColorAndroid={'transparent'}
            style={styles.searchInput}
            value={this.state.searchString}
            onChange={this._onSearchTextChanged}
            placeholder='Search via name or postcode' />
          <Button
            onPress={() => {}}
            color='#48bbec'
            title='Go'
          />
        </View>
        <Image source={require('./Resources/house.png')} style={styles.image} />
      </View>    
    );
  }
}

const styles = StyleSheet.create({
  description: {
    fontSize: 18,
    textAlign: 'center',
    color: '#656565',
    marginBottom: 20,
  },
  container: {
    padding: 30,
    marginTop: 65,
    alignItems: 'center',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
  flowRight: {
    flexDirection: 'row',
    alignItems: 'center',
    alignSelf: 'stretch',
  },
  searchInput: {
    height: 36,
    padding: 4,
    marginRight: 5,
    flexGrow: 1,
    fontSize: 18,
    borderWidth: 1,
    borderColor: '#48bbec',
    borderRadius: 8,
    color: '#48bbec',
  },
  image: {
    width: 217,
    height: 138,
  },
});

App.js

'use strict';
/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */

import React, { Component } from 'react';
import {
  Platform,
  StyleSheet,
  Text,
  View
} from 'react-native';
import { StackNavigator } from 'react-navigation';

import SearchPage from './SearchPage';

// type Props = {};

const App = StackNavigator({
  Home: {
    screen: SearchPage,
  },
});
export default App;

My English is not good, Sorry.