hooks-in-react-native-2.jsx

import React, { useState, useEffect } from 'react';
import { View, Text, Button } from 'react-native';

export const Example = () => {
  const [foo, setFoo] = useState(30);

  useEffect(() => {
    if (foo >= 42) {
      setFoo(42);
    }
  }, [foo])

  return (
    <view>
      <text>Foo is {foo}.</text>
      <button onpress={() => setFoo(foo + 1)} title='Increase Foo!' />
    </view>
  )
}