Custom useKeyboardAvoiding Hook: Adjusting View Translation Based on Keyboard Height in Expo/React Native

Building mobile apps with Expo and React Native often involves working with user inputs like text fields and forms. One common challenge arises when the keyboard appears, potentially covering the input field. This is where keyboard avoidance comes into play. This article delves into the custom `useKeyboardAvoiding` hook, a powerful tool to dynamically adjust view translations based on keyboard height, ensuring your inputs remain visible and user-friendly.

We'll explore the rationale behind custom hooks, the concepts of keyboard events, and how to implement a robust `useKeyboardAvoiding` hook. By the end, you'll be equipped with the knowledge to seamlessly manage keyboard interactions within your Expo/React Native projects.

Why Custom `useKeyboardAvoiding` Hooks?

React Native's default `KeyboardAvoidingView` component is a helpful starting point for keyboard avoidance. However, it might not always meet the specific requirements of your app's UI design. You might need more granular control over:

Custom Animation: Beyond simple view translations, you might want to implement custom animations or effects for smoother user interactions.
Specific View Targeting: The default `KeyboardAvoidingView` might cover more views than intended. A custom hook allows precise targeting of the view you want to adjust.
Advanced Logic: More complex scenarios might require custom logic based on factors like keyboard height, view dimensions, and screen orientation.

A custom `useKeyboardAvoiding` hook provides this fine-grained control, allowing you to tailor keyboard avoidance to your specific app's needs.

Understanding Keyboard Events and View Translation

At the core of keyboard avoidance is the ability to react to keyboard events. React Native provides the following events:

`KeyboardDidShow`: Fired when the keyboard is displayed.
`KeyboardDidHide`: Fired when the keyboard is dismissed.
`KeyboardWillShow`: (Deprecated in newer React Native versions) Fired when the keyboard is about to appear.
`KeyboardWillHide`: (Deprecated in newer React Native versions) Fired when the keyboard is about to disappear.

By listening to these events, your custom hook can obtain crucial information about the keyboard, including its height and the current screen dimensions. This information is then used to calculate the necessary translation for your target view, ensuring it remains visible above the keyboard.

Implementing the `useKeyboardAvoiding` Hook

Let's create a custom `useKeyboardAvoiding` hook. This example demonstrates a basic implementation, which can be further extended based on your application's needs:

import React, { useState, useEffect } from 'react';
import { Dimensions, Keyboard } from 'react-native';

const useKeyboardAvoiding = (ref, offset = 0) =&gt; {
  const [keyboardHeight, setKeyboardHeight] = useState(0);

  useEffect(() =&gt; {
    const keyboardDidShowListener = Keyboard.addListener(
      'keyboardDidShow',
      (event) =&gt; {
        setKeyboardHeight(event.endCoordinates.height);
      }
    );

    const keyboardDidHideListener = Keyboard.addListener(
      'keyboardDidHide',
      () =&gt; {
        setKeyboardHeight(0);
      }
    );

    return () =&gt; {
      keyboardDidShowListener.remove();
      keyboardDidHideListener.remove();
    };
  }, []);

  const getTranslation = () =&gt; {
    const { height: screenHeight } = Dimensions.get('window');
    return keyboardHeight + offset - screenHeight;
  };

  return {
    translateY: getTranslation(),
  };
};

export default useKeyboardAvoiding;

Let's break down the code:

Import necessary modules: We import useState, useEffect from React, Dimensions and Keyboard from React Native.
useKeyboardAvoiding function: This hook takes two parameters:
- ref: A reference to the view you want to adjust.
- offset: An optional offset to customize the translation.
State management: We use useState to track keyboardHeight.
Keyboard event listeners:
- useEffect is used to set up event listeners for keyboardDidShow and keyboardDidHide.
- These listeners update the keyboardHeight state based on the keyboard's height.
- The cleanup function inside useEffect ensures listeners are removed when the component unmounts.
getTranslation function: This calculates the translation value based on the keyboardHeight, screenHeight, and the provided offset.
Return values: The hook returns an object with translateY, containing the calculated translation value.

Integrating the Hook with Your Component

Now, let's see how to integrate this hook within a component:

import React, { useRef } from 'react';
import { View, Text, StyleSheet, Animated } from 'react-native';
import useKeyboardAvoiding from './useKeyboardAvoiding';

const MyComponent = () =&gt; {
  const inputRef = useRef(null);
  const { translateY } = useKeyboardAvoiding(inputRef);

  const animatedTranslateY = useRef(new Animated.Value(translateY)).current;

  useEffect(() =&gt; {
    Animated.timing(animatedTranslateY, {
      toValue: translateY,
      duration: 300,
      useNativeDriver: true,
    }).start();
  }, [translateY]);

  return (
<view style="{styles.container}">
 <animated.view [{="" animatedtranslatey="" style="{[styles.inputContainer," transform:="" translatey:="" {="" }]="" }]}="">
  <text>
   This is a text field
  </text>
  <view ref="{inputRef}" style="{styles.input}">
  </view>
 </animated.view>
</view>
);
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
  inputContainer: {
    width: 200,
    height: 100,
    backgroundColor: '#ccc',
  },
  input: {
    height: 40,
    backgroundColor: '#fff',
  },
});

export default MyComponent;

In this example:

Input ref: We create a ref for the input view (inputRef).
useKeyboardAvoiding usage: We call the useKeyboardAvoiding hook, passing the inputRef and an optional offset.
Animation: We use an Animated.Value to manage the translation animation. useEffect updates the animation value whenever translateY changes.
View styling: We apply the animated translation to the inputContainer style.
This code creates a simple component with a text field that will automatically adjust its position based on the keyboard's presence. The translation is animated for a smoother user experience.
## Enhancements and Customizations
This basic hook can be enhanced to suit more complex scenarios:
### 1. Custom Animations
You can use different Animated methods to create custom animations. For example, you can use Animated.spring for a bouncy effect or Animated.decay for a smooth deceleration.
### 2. Multiple Views
You can adapt the hook to adjust multiple views by maintaining a state object that maps view references to their corresponding translations.
### 3. Screen Orientation Handling
Consider adding logic to dynamically adjust the translation based on screen orientation. This ensures your views remain visible regardless of device rotation.
### 4. View Dimensions
You might want to factor in the view's dimensions when calculating the translation to fine-tune its placement above the keyboard.
### 5. Advanced Logic
Your custom hook can implement more sophisticated logic, taking into account factors like keyboard type, keyboard appearance, and other app-specific requirements.
## Conclusion
Custom useKeyboardAvoiding hooks offer a powerful and flexible way to handle keyboard interactions in your Expo/React Native apps. By understanding keyboard events, view translation, and animation techniques, you can craft custom hooks that seamlessly adjust your views and create a positive user experience. Remember to adapt the hook's logic and animations to match the specific requirements of your application, ensuring your app is both functional and visually appealing.