React Native Picker

React Native Picker

This post will give you an Understanding of How Picker Works in React Native. React Native Picker is a component for selection between different choices same as a Dropdown. Picker can be used when we have to give an option to pick one. There are multiple types of picker available which we will see one by one in upcoming tutorials. Have a look at the simple picker which has multiple options and the user has to choose one.

To Import Picker in Code

import {Picker} from '@react-native-picker/picker'

Render Using

<Picker>
  <Picker.Item label = "label here" value = "value here" />
</Picker>

To Make a React Native App

Getting started with React Native will help you to know more about the way you can make a React Native project. We are going to use react native command line interface to make our React Native App.

If you have previously installed a global react-native-cli package, please remove it as it may cause unexpected issues:

npm uninstall -g react-native-cli @react-native-community/cli

Run the following commands to create a new React Native project

npx react-native init ProjectName

If you want to start a new project with a specific React Native version, you can use the --version argument:

npx react-native init ProjectName --version X.XX.X

Note If the above command is failing, you may have old version of react-native or react-native-cli installed globally on your pc. Try uninstalling the cli and run the cli using npx.

This will make a project structure with an index file named App.js in your project directory.

Installation of Dependency

To use Picker we need to install @react-native-picker/picker dependency. To install this open the terminal and jump into your project using

cd ProjectName

Run the following command to install

npm install @react-native-picker/picker --save

This command will copy all the dependency into your node_module directory. –save is optional, it is just to update the @react-native-picker/picker dependency in your package.json file.

CocoaPods Installation

We need to install the pods for iOS

npx pod-install

Code

Open App.js in any code editor and replace the code with the following code

App.js

//React Native Picker
//https://aboutreact.com/react-native-picker/

//import React in our code
import React, {useState} from 'react';

//import all the components we are going to use
import {
  View,
  Text,
  SafeAreaView,
  StyleSheet
} from 'react-native';

import {Picker} from '@react-native-picker/picker';

const App = () => {
  const [choosenLabel, setChoosenLabel] = useState('Native');
  const [choosenIndex, setChoosenIndex] = useState('2');

  return (
    <SafeAreaView style={{flex: 1}}>
      <View style={styles.container}>
        {/*Picker with multiple chose to choose*/}
        {/*selectedValue to set the preselected value if any*/}
        {/*onValueChange will help to handle the changes*/}
        <Picker
          selectedValue={choosenLabel}
          onValueChange={(itemValue, itemIndex) => {
            setChoosenLabel(itemValue);
            setChoosenIndex(itemIndex);
          }}>
          <Picker.Item label="Hello" value="Hello" />
          <Picker.Item label="React" value="React" />
          <Picker.Item label="Native" value="Native" />
          <Picker.Item label="How" value="How" />
          <Picker.Item label="are" value="are" />
          <Picker.Item label="you" value="you" />
        </Picker>
        {/*Text to show selected picker value*/}
        <Text style={styles.text}>
          Selected Value: {choosenLabel}
        </Text>
        {/*Text to show selected index */}
        <Text style={styles.text}>
          Selected Index: {choosenIndex}
        </Text>
      </View>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    flexDirection: 'column',
  },
  text: {
    fontSize: 20,
    alignSelf: 'center',
  },
});

export default App;

App.js(Value populated in picker using rest API)

//React Native Picker
//https://aboutreact.com/react-native-picker/

//import React in our code
import React, {useState, useEffect} from 'react';

//import all the components we are going to use
import {
  View,
  Text,
  SafeAreaView,
  StyleSheet
} from 'react-native';

import {Picker} from '@react-native-picker/picker';

const App = () => {
  const [choosenValue, setChoosenValue] = useState(2);
  const [choosenIndex, setChoosenIndex] = useState(1);
  const [data, setData] = useState([]);

  useEffect(()=>{
    //GET request
    fetch('https://jsonplaceholder.typicode.com/posts', {
      method: 'GET',
      //Request Type
    })
      .then((response) => response.json())
      //If response is in json then in success
      .then((responseJson) => {
        //Success
        //alert(JSON.stringify(responseJson));
        // console.log(responseJson);
        setData(responseJson);
      })
      //If response is not in json then in error
      .catch((error) => {
        //Error
        alert(JSON.stringify(error));
        console.error(error);
      });
  });

  return (
    <SafeAreaView style={{flex: 1}}>
      <View style={styles.container}>
        {/*Picker with multiple chose to choose*/}
        {/*selectedValue to set the preselected value if any*/}
        {/*onValueChange will help to handle the changes*/}
        <Picker
          selectedValue={choosenValue}
          onValueChange={(itemValue, itemIndex) => {
            setChoosenValue(itemValue);
            setChoosenIndex(itemIndex);
          }}>
          {
            data.map(item =>{
              return <Picker.Item value={item.id} label={item.title} />    
            })
          }
        </Picker>
        {/*Text to show selected picker value*/}
        <Text style={styles.text}>
          Selected Value: {choosenValue}
        </Text>
        {/*Text to show selected index */}
        <Text style={styles.text}>
          Selected Index: {choosenIndex}
        </Text>
      </View>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    flexDirection: 'column',
  },
  text: {
    fontSize: 20,
    alignSelf: 'center',
  },
});

export default App;

To Run the React Native App

Open the terminal again and jump into your project using.

cd ProjectName

1. Start Metro Bundler

First, you will need to start Metro, the JavaScript bundler that ships with React Native. To start Metro bundler run following command:

npx react-native start

Once you start Metro Bundler it will run forever on your terminal until you close it. Let Metro Bundler run in its own terminal. Open a new terminal and run the application.

2. Start React Native Application

To run the project on an Android Virtual Device or on real debugging device:

npx react-native run-android

or on the iOS Simulator by running (macOS only)

npx react-native run-ios

Output Screenshot

Output in Online Emulator

That was the React Native Picker. If you have any doubts or you want to share something about the topic you can comment below or contact us here. The remaining components will be covered in the next article. Stay tuned!

Hope you liked it. 🙂