Switch and checkbox patterns in React Native - Mini App: Build & Ship

Build: Settings Screen

A simple settings screen with a switch and a checkbox to toggle preferences.

Target UI

Settings Screen

[ ] Enable Notifications

Switch: Dark Mode [ ON ]

Add a checkbox labeled 'Enable Notifications' that toggles on/off

Add a switch labeled 'Dark Mode' that toggles on/off

Display the current state of both controls below them as text

Use React Native components and hooks

Starter Code

React Native

import React, { useState } from 'react';
import { View, Text, Switch, TouchableOpacity } from 'react-native';

export default function SettingsScreen() {
  // TODO: Add state hooks for checkbox and switch

  return (
    <View style={{ flex: 1, padding: 20, justifyContent: 'center' }}>
      {/* TODO: Add checkbox component here */}

      {/* TODO: Add switch component here */}

      {/* TODO: Show current states here */}
    </View>
  );
}

Task 1

Task 2

Task 3

Task 4

Solution

React Native

import React, { useState } from 'react';
import { View, Text, Switch, TouchableOpacity } from 'react-native';

export default function SettingsScreen() {
  const [notificationsEnabled, setNotificationsEnabled] = useState(false);
  const [darkModeEnabled, setDarkModeEnabled] = useState(false);

  const toggleNotifications = () => setNotificationsEnabled(prev => !prev);
  const toggleDarkMode = () => setDarkModeEnabled(prev => !prev);

  return (
    <View style={{ flex: 1, padding: 20, justifyContent: 'center' }}>
      <TouchableOpacity
        onPress={toggleNotifications}
        style={{ flexDirection: 'row', alignItems: 'center', marginBottom: 20 }}
        accessibilityRole="checkbox"
        accessibilityState={{ checked: notificationsEnabled }}
        accessibilityLabel="Enable Notifications"
      >
        <View
          style={{
            height: 24,
            width: 24,
            borderWidth: 2,
            borderColor: '#333',
            backgroundColor: notificationsEnabled ? '#333' : 'transparent',
            marginRight: 10,
            justifyContent: 'center',
            alignItems: 'center'
          }}
        >
          {notificationsEnabled && (
            <Text style={{ color: 'white', fontWeight: 'bold' }}>✓</Text>
          )}
        </View>
        <Text style={{ fontSize: 18 }}>Enable Notifications</Text>
      </TouchableOpacity>

      <View style={{ flexDirection: 'row', alignItems: 'center', marginBottom: 20 }}>
        <Text style={{ fontSize: 18, marginRight: 10 }}>Dark Mode</Text>
        <Switch
          value={darkModeEnabled}
          onValueChange={toggleDarkMode}
          accessibilityLabel="Dark Mode"
        />
      </View>

      <Text style={{ fontSize: 16, marginBottom: 5 }}>
        Notifications are {notificationsEnabled ? 'ON' : 'OFF'}
      </Text>
      <Text style={{ fontSize: 16 }}>
        Dark Mode is {darkModeEnabled ? 'ON' : 'OFF'}
      </Text>
    </View>
  );
}

We use useState to keep track of the checkbox and switch states. The checkbox is built using a TouchableOpacity with a square box that fills with a checkmark when enabled. The switch uses React Native's built-in Switch component. Accessibility roles and labels are added for screen readers. The current states are shown below as simple text to confirm the toggles work.

Final Result

Completed Screen

Settings Screen

[✓] Enable Notifications

Dark Mode: [ ON ]

Notifications are ON
Dark Mode is ON

Tap the checkbox area to toggle notifications on or off

Toggle the switch to turn dark mode on or off

Text below updates to show current states

Stretch Goal

Add a reset button that sets both toggles back to OFF

💡 Hint

Use a Button component and set both states to false on press

Practice

1. What is the main purpose of a Switch component in React Native?

easy

A. To toggle between two states like ON and OFF

B. To select multiple options from a list

C. To input text from the user

D. To display images in a gallery

Solution

1. Step 1: Understand the Switch component

   A Switch is a UI element that lets users toggle between two states, usually ON or OFF.

2. Step 2: Compare with other components

   Checkboxes allow multiple selections, text inputs accept text, and image galleries display images, so these do not match the Switch's purpose.

3. Final Answer:

   To toggle between two states like ON and OFF -> Option A

4. Quick Check:

   Switch toggles states = B [OK]

Hint: Switch means ON/OFF toggle, not multiple selections [OK]

Common Mistakes:

• Confusing Switch with Checkbox
• Thinking Switch accepts text input
• Assuming Switch displays images

2. Which of the following is the correct way to declare a controlled Switch component in React Native?

easy

A. setIsOn(!isOn)} />

B. setIsOn(!isOn)} />

C. setIsOn(!isOn)} />

D. setIsOn(!isOn)} />

Solution

1. Step 1: Recall Switch props in React Native

   The Switch component uses value to set its state and onValueChange as the event handler for toggling.

2. Step 2: Identify correct syntax

   Options using checked or onChange are incorrect because React Native Switch does not use these props.

3. Final Answer:

   <Switch value={isOn} onValueChange={() => setIsOn(!isOn)} /> -> Option D

4. Quick Check:

   Switch uses value and onValueChange = C [OK]

Hint: Switch uses value and onValueChange props [OK]

Common Mistakes:

• Using checked instead of value
• Using onChange instead of onValueChange
• Mixing HTML input props with React Native Switch

3. What will be the output on the screen after running this React Native code snippet?

const [checked, setChecked] = React.useState(false);

return (
  <CheckBox
    value={checked}
    onValueChange={() => setChecked(!checked)}
  />
);

If the user taps the checkbox once, what is the new value of checked?

medium

A. false

B. true

C. undefined

D. null

Solution

1. Step 1: Initial state value

   The state variable checked starts as false.

2. Step 2: Effect of tapping checkbox

   The onValueChange toggles checked to its opposite, so it becomes true after one tap.

3. Final Answer:

   true -> Option B

4. Quick Check:

   Toggle false once = true [OK]

Hint: Tapping toggles boolean state from false to true [OK]

Common Mistakes:

• Assuming state stays false after tap
• Confusing value prop with event
• Thinking onValueChange returns new value

4. Identify the error in this React Native code for a controlled Switch:

const [isEnabled, setIsEnabled] = React.useState(false);

return (
  <Switch
    value={isEnabled}
    onChange={() => setIsEnabled(!isEnabled)}
  />
);

medium

A. Using value instead of checked

B. Missing initial state declaration

C. Using onChange instead of onValueChange

D. Not importing React

Solution

1. Step 1: Check event handler prop

   The Switch component uses onValueChange to handle toggle events, not onChange.

2. Step 2: Verify other parts

   The initial state is declared, value is correct, and React import is assumed correct.

3. Final Answer:

   Using onChange instead of onValueChange -> Option C

4. Quick Check:

   Switch needs onValueChange, not onChange [OK]

Hint: Switch uses onValueChange, not onChange [OK]

Common Mistakes:

• Using onChange event instead of onValueChange
• Confusing value and checked props
• Forgetting to declare state

5. You want to create a list of three checkboxes in React Native where only one can be selected at a time (like radio buttons). Which approach correctly implements this behavior?

hard

A. Use three CheckBox components sharing one state variable that stores the selected option

B. Use one CheckBox component and change its label dynamically

C. Use three CheckBox components each with its own boolean state variable

D. Use three Switch components each with independent state variables

Solution

1. Step 1: Understand single selection requirement

   Only one checkbox can be selected at a time, so all must share one state that tracks which is selected.

2. Step 2: Evaluate options

   Use three CheckBox components sharing one state variable that stores the selected option. This uses one state variable to store the selected option and updates it on selection, ensuring only one is selected. Options A and C use independent states allowing multiple selections. Use one CheckBox component and change its label dynamically uses only one checkbox, which cannot represent three options.

3. Final Answer:

   Use three CheckBox components sharing one state variable that stores the selected option -> Option A

4. Quick Check:

   Single selection needs shared state = D [OK]

Hint: Single selection means one state tracks selected checkbox [OK]

Common Mistakes:

• Giving each checkbox its own state allowing multiple selections
• Using Switch instead of CheckBox for selection list
• Trying to reuse one checkbox for multiple options