Custom tab bars in React Native - Deep Dive

Overview - Custom tab bars

What is it?

Custom tab bars are personalized navigation bars at the bottom or top of a mobile app screen that let users switch between different sections. Instead of using the default tab bar provided by a library, developers create their own design and behavior to match the app's style and needs. This allows more control over how tabs look and respond to user actions.

Why it matters

Custom tab bars exist because default tab bars can be too plain or not fit the app's unique style and user experience goals. Without custom tab bars, apps might look generic or confuse users with unclear navigation. Custom tab bars help apps stand out, improve usability, and provide a smoother way for users to move around the app.

Where it fits

Before learning custom tab bars, you should understand basic React Native components and navigation concepts like stack and tab navigation. After mastering custom tab bars, you can explore advanced navigation patterns, animations, and integrating custom gestures for richer user experiences.

Mental Model

Core Idea

A custom tab bar is a user-made navigation control that replaces the default tabs to provide unique style and behavior tailored to the app's needs.

Think of it like...

It's like replacing the standard buttons on a remote control with your own custom buttons that look nicer and do exactly what you want, making it easier and more enjoyable to switch channels.

┌─────────────────────────────┐
│       App Screen Area        │
│                             │
│                             │
│                             │
├─────────────────────────────┤
│ ◉ Home  ◯ Search  ◯ Profile │  <-- Custom Tab Bar with buttons
└─────────────────────────────┘

Build-Up - 6 Steps

1

Foundation

Understanding basic tab navigation

Concept: Learn what tab navigation is and how default tab bars work in React Native.

Tab navigation lets users switch between different screens by tapping tabs. React Navigation provides a default tab bar that shows icons and labels for each tab automatically.

Result

You see a simple tab bar at the bottom with default styles and can switch screens by tapping tabs.

Knowing how default tab bars work helps you understand what you can customize and why you might want to replace them.

2

Foundation

Creating a simple custom tab bar component

Concept: Build a React component that renders buttons to act as tabs instead of using the default tab bar.

Create a functional component that receives navigation state and renders buttons for each tab. Use TouchableOpacity for taps and Text or Icons for labels.

Result

You have a basic custom tab bar that shows buttons and can detect taps, but it doesn't yet control navigation.

Building the UI first lets you separate appearance from navigation logic, making customization easier.

3

Intermediate

Connecting custom tab bar to navigation state

🤔Before reading on: do you think the custom tab bar can change screens automatically without extra code? Commit to yes or no.

Concept: Link the custom tab bar buttons to React Navigation's navigation methods to switch screens on tap.

Use the navigation prop's navigate function inside button onPress handlers to switch tabs. Also, highlight the active tab based on the current route index.

Result

Tapping a custom tab button changes the screen, and the active tab visually updates.

Understanding how navigation state and actions connect to UI lets you control app flow precisely.

4

Intermediate

Adding icons and animations to tabs

🤔Before reading on: do you think adding animations to tab buttons requires complex libraries or can be done with simple React Native APIs? Commit to your guess.

Concept: Enhance the custom tab bar by adding icons and simple animations like scaling or color changes on active tabs.

Use vector icons libraries for tab icons. Use Animated API or Reanimated to smoothly animate tab button styles when active or pressed.

Result

Tabs show icons and animate smoothly when selected, improving user feedback and polish.

Small visual touches like animations greatly improve user experience and app feel.

5

Advanced

Handling safe areas and responsiveness

🤔Before reading on: do you think custom tab bars automatically handle device safe areas like notches? Commit to yes or no.

Concept: Make sure the custom tab bar respects device safe areas and adapts to different screen sizes and orientations.

Use SafeAreaView or react-native-safe-area-context to avoid overlaps with notches or home indicators. Use Flexbox and percentage widths for responsive layout.

Result

The custom tab bar looks good and is fully usable on all devices without UI clipping or overlap.

Accounting for device differences prevents frustrating UI bugs and ensures a professional app appearance.

6

Expert

Optimizing performance and accessibility

🤔Before reading on: do you think custom tab bars need special accessibility props to be usable by screen readers? Commit to yes or no.

Concept: Improve custom tab bars by optimizing rendering and adding accessibility features for all users.

Use React.memo or PureComponent to avoid unnecessary re-renders. Add accessibilityLabel, accessibilityRole, and keyboard navigation support to tab buttons.

Result

The custom tab bar is fast, smooth, and usable by people relying on assistive technologies.

Performance and accessibility are key to professional apps and often overlooked in custom UI components.

Under the Hood

React Navigation manages navigation state internally and provides props to custom tab bars, including the current route index and navigation methods. The custom tab bar uses these props to render tabs and call navigation.navigate to switch screens. React Native renders the tab bar component as part of the UI tree, updating it when navigation state changes. Animations use native driver or JS thread to smoothly update styles.

Why designed this way?

React Navigation separates navigation logic from UI to allow flexibility. Default tab bars cover common cases, but custom tab bars let developers tailor appearance and behavior without changing navigation internals. This design balances ease of use with customization power.

┌───────────────┐       ┌─────────────────────┐
│ Navigation    │       │ Custom Tab Bar      │
│ State & Logic │──────▶│ Receives state &    │
└───────────────┘       │ navigation methods  │
                        └─────────┬───────────┘
                                  │
                      ┌───────────▼───────────┐
                      │ Renders buttons &     │
                      │ handles taps to       │
                      │ call navigation       │
                      └───────────────────────┘

Myth Busters - 3 Common Misconceptions

Quick: do you think a custom tab bar automatically handles navigation without extra code? Commit to yes or no.

Common Belief: A custom tab bar just replaces the look and automatically switches screens without extra setup.

Reality: Custom tab bars must explicitly call navigation methods to switch screens; they only replace the UI, not the navigation logic.

Why it matters: Without connecting navigation actions, the custom tab bar buttons won't change screens, confusing users and breaking app flow.

Quick: do you think default tab bars always look good on all devices without adjustments? Commit to yes or no.

Common Belief: Default tab bars handle all device safe areas and screen sizes perfectly out of the box.

Reality: Default tab bars handle safe areas, but custom tab bars must manually handle safe areas and responsiveness to avoid UI issues.

Why it matters: Ignoring safe areas causes tab bars to overlap notches or home indicators, making buttons hard to tap or see.

Quick: do you think adding animations to custom tab bars requires complex third-party libraries? Commit to yes or no.

Common Belief: Animations in custom tab bars need heavy libraries and complex code.

Reality: Simple animations like scaling or color changes can be done with React Native's built-in Animated API easily.

Why it matters: Believing animations are hard may stop developers from improving user experience with smooth feedback.

Expert Zone

1

Custom tab bars can intercept gestures and add swipe navigation between tabs, improving UX beyond taps.

2

Using React.memo or useCallback prevents unnecessary re-renders of tab buttons, which is crucial for performance in complex apps.

3

Accessibility props like accessibilityRole='tab' and accessibilityState help screen readers announce tab status correctly, often missed in custom implementations.

When NOT to use

Avoid custom tab bars if your app's navigation needs are simple and the default tab bar fits well, as custom bars add maintenance overhead. For very complex navigation, consider drawer or stack navigators instead.

Production Patterns

In production, custom tab bars often include badges for notifications, dynamic tab visibility based on user roles, and integration with analytics to track tab usage. They also use theme context to adapt colors dynamically.

Connections

State Management

Builds-on

Understanding how navigation state flows and updates helps in syncing custom tab bars with app-wide state for consistent UI.

User Experience Design

Builds-on

Custom tab bars are a direct application of UX principles, showing how design choices affect navigation clarity and user satisfaction.

Human-Computer Interaction (HCI)

Builds-on

Custom tab bars embody HCI concepts like affordance and feedback, teaching how interface elements communicate function and state to users.

Common Pitfalls

#1 Tab buttons do not switch screens when tapped.

Wrong approach:

const CustomTabBar = ({ state }) => {
return (

{state.routes.map((route, index) => (

{route.name}

))}

);
};

Correct approach:

const CustomTabBar = ({ state, navigation }) => {
return (

{state.routes.map((route, index) => (
navigation.navigate(route.name)}
>
{route.name}

))}

);
};

Root cause:

The developer forgot to call navigation.navigate on button press, so taps do nothing.

#2 Custom tab bar overlaps device notch or home indicator.

Wrong approach:

{/* tab buttons */}

Correct approach:

import { SafeAreaView } from 'react-native-safe-area-context';

{/* tab buttons */}

Root cause:

Ignoring safe area insets causes UI to overlap device-specific screen areas.

#3 Tab buttons re-render unnecessarily causing lag.

Wrong approach:

const CustomTabBar = ({ state, navigation }) => {
return (

{state.routes.map(route => (
navigation.navigate(route.name)}>
{route.name}

))}

);
};

Correct approach:

const TabButton = React.memo(({ route, isFocused, onPress }) => {
return (

{route.name}

);
});

const CustomTabBar = ({ state, navigation }) => {
return (

{state.routes.map((route, index) => {
const isFocused = state.index === index;
return (
navigation.navigate(route.name)}
/>
);
})}

);
};

Root cause:

Not memoizing tab buttons causes all buttons to re-render on any state change.

Key Takeaways

Custom tab bars let you replace default navigation tabs with personalized designs and behaviors.

They require connecting UI buttons to navigation actions to switch screens properly.

Handling device safe areas and responsiveness is essential for a polished, usable tab bar.

Adding animations and accessibility features improves user experience and inclusivity.

Optimizing rendering with memoization prevents performance issues in complex apps.