LayoutAnimation in React Native - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is LayoutAnimation in React Native?

LayoutAnimation is a React Native API that allows you to animate layout changes smoothly, like when views change size or position.

beginner

How do you trigger a LayoutAnimation in React Native?

You call LayoutAnimation.configureNext() before the state change that causes the layout update.

beginner

Name one built-in animation preset in LayoutAnimation.

Examples include LayoutAnimation.Presets.easeInEaseOut, spring, and linear.

intermediate

Why do you need to enable LayoutAnimation on Android explicitly?

Because on Android, you must enable it with UIManager.setLayoutAnimationEnabledExperimental(true) for it to work.

beginner

What kind of UI changes can LayoutAnimation animate?

It animates layout changes like view size, position, and adding or removing views.

Which method triggers a layout animation in React Native?

A LayoutAnimation.configureNext()

B Animated.timing()

C setTimeout()

D useEffect()

LayoutAnimation.configureNext() tells React Native to animate the next layout change.

What must you do on Android to use LayoutAnimation?

A Nothing special, it works by default

B Import Animated from react-native

C Use a third-party library

D Call UIManager.setLayoutAnimationEnabledExperimental(true)

On Android, you must enable LayoutAnimation explicitly with UIManager.setLayoutAnimationEnabledExperimental(true).

Which of these is NOT a LayoutAnimation preset?

A linear

B spring

C bounce

D easeInEaseOut

bounce is not a built-in LayoutAnimation preset.

When should you call LayoutAnimation.configureNext()?

A Before the layout change

B After the layout change

C Only on app start

D Only on Android

You call it before the state change that triggers the layout update.

What does LayoutAnimation animate?

A Only color changes

B Layout changes like size and position

C Text changes

D Network requests

LayoutAnimation animates changes in layout such as size and position.

Explain how to use LayoutAnimation to animate a view resizing in React Native.

Think about when and how to call the animation before changing the view size.

Describe why LayoutAnimation is useful for improving user experience in mobile apps.

Consider how animations help users understand changes on screen.

Practice

1. What is the main purpose of LayoutAnimation in React Native?

easy

A. To handle network requests asynchronously

B. To animate layout changes smoothly when views change size or position

C. To manage app navigation between screens

D. To style components with CSS-like rules

Solution

1. Step 1: Understand what LayoutAnimation does

   LayoutAnimation is used to animate changes in layout, like when a view grows or moves.

2. Step 2: Compare with other options

   The other options relate to networking, navigation, and styling, which are unrelated to layout animation.

3. Final Answer:

   To animate layout changes smoothly when views change size or position -> Option B

4. Quick Check:

   LayoutAnimation = Animate layout changes [OK]

Hint: LayoutAnimation = smooth layout changes animation [OK]

Common Mistakes:

• Confusing LayoutAnimation with navigation or styling
• Thinking it handles data fetching
• Assuming it animates only opacity or color

2. Which of the following is the correct way to trigger a layout animation before a state change?

easy

A. LayoutAnimation.configureNext(LayoutAnimation.Presets.easeInEaseOut); setState({expanded: true});

B. LayoutAnimation.start(); setState({expanded: true});

C. LayoutAnimation.animate(); setState({expanded: true});

D. LayoutAnimation.begin(); setState({expanded: true});

Solution

1. Step 1: Recall the correct method to start animation

   The official method is configureNext with a preset before changing state.

2. Step 2: Check method names

   Only LayoutAnimation.configureNext(LayoutAnimation.Presets.easeInEaseOut); setState({expanded: true}); uses configureNext and a valid preset. Others use invalid methods.

3. Final Answer:

   LayoutAnimation.configureNext(LayoutAnimation.Presets.easeInEaseOut); setState({expanded: true}); -> Option A

4. Quick Check:

   Use configureNext before state change [OK]

Hint: Use configureNext with preset before state change [OK]

Common Mistakes:

• Using non-existent methods like start or animate
• Calling animation after state change
• Forgetting to import LayoutAnimation

3. Given this code snippet, what will happen when the button is pressed?

import React from 'react';
import { LayoutAnimation, UIManager, Platform, View, Button } from 'react-native';

if (Platform.OS === 'android') {
  UIManager.setLayoutAnimationEnabledExperimental(true);
}

const MyComponent = () => {
  const [expanded, setExpanded] = React.useState(false);

  const toggle = () => {
    LayoutAnimation.configureNext(LayoutAnimation.Presets.spring);
    setExpanded(!expanded);
  };

  return (
    
      
      
    
  );
};

medium

A. The button does not respond to presses

B. The blue box instantly changes height without animation

C. The app crashes on Android due to missing permissions

D. The blue box smoothly expands or shrinks height with a spring animation

Solution

1. Step 1: Understand the animation setup

   UIManager enables animation on Android. LayoutAnimation.configureNext with spring preset is called before state change.

2. Step 2: Analyze the effect on the blue box

   The height toggles between 100 and 200, so the box smoothly animates height change with spring effect.

3. Final Answer:

   The blue box smoothly expands or shrinks height with a spring animation -> Option D

4. Quick Check:

   configureNext + state change = smooth animation [OK]

Hint: configureNext + state toggle = smooth layout animation [OK]

Common Mistakes:

• Ignoring UIManager setup on Android
• Thinking animation is instant
• Assuming button is unresponsive

4. What is wrong with this code snippet that tries to animate a layout change?

import React from 'react';
import { LayoutAnimation, View, Button } from 'react-native';

const MyComponent = () => {
  const [visible, setVisible] = React.useState(false);

  const toggle = () => {
    setVisible(!visible);
    LayoutAnimation.configureNext(LayoutAnimation.Presets.easeInEaseOut);
  };

  return (
    
      
      {visible && }
    
  );
};

medium

A. LayoutAnimation requires a custom config, presets don't work

B. The red box style is missing width, causing layout error

C. LayoutAnimation.configureNext is called after the state change, so animation won't run

D. Button onPress should be async for animation to work

Solution

1. Step 1: Check order of animation and state change

   Animation must be configured before the state change triggers layout update.

2. Step 2: Identify the mistake

   Here, setVisible is called before configureNext, so animation is not applied to the layout change.

3. Final Answer:

   LayoutAnimation.configureNext is called after the state change, so animation won't run -> Option C

4. Quick Check:

   configureNext must come before state change [OK]

Hint: Call configureNext before state change to animate [OK]

Common Mistakes:

• Calling configureNext after setState
• Forgetting to enable animation on Android
• Assuming presets need custom config

5. You want to create a custom layout animation that fades and scales a view when it appears or disappears. Which approach correctly uses LayoutAnimation to achieve this effect?

hard

A. Use LayoutAnimation.configureNext with a custom config specifying duration, create with property: 'opacity' and update with type: 'scaleXY'

B. Use Animated.timing on opacity and scale values instead of LayoutAnimation

C. Call LayoutAnimation.configureNext(LayoutAnimation.Presets.linear) without custom config

D. Wrap the view in a ScrollView and animate scroll position

Solution

1. Step 1: Understand custom LayoutAnimation config

   Custom configs can specify duration and animation types for create, update, and delete phases.

2. Step 2: Match animation properties to fade and scale

   Fading uses opacity property, scaling uses scaleXY type in update phase.

3. Step 3: Evaluate options

   Use LayoutAnimation.configureNext with a custom config specifying duration, create with property: 'opacity' and update with type: 'scaleXY' correctly uses configureNext with a custom config for opacity and scale. Use Animated.timing on opacity and scale values instead of LayoutAnimation uses Animated API, not LayoutAnimation. Call LayoutAnimation.configureNext(LayoutAnimation.Presets.linear) without custom config uses preset without scale. Wrap the view in a ScrollView and animate scroll position is unrelated.

4. Final Answer:

   Use LayoutAnimation.configureNext with a custom config specifying duration, create with property: 'opacity' and update with type: 'scaleXY' -> Option A

5. Quick Check:

   Custom config with opacity and scaleXY = fade and scale [OK]

Hint: Custom config with opacity and scaleXY for fade+scale [OK]

Common Mistakes:

• Using presets only for scale animations
• Confusing Animated API with LayoutAnimation
• Not specifying create and update properties