长话短说。React使用函数组件，如果你不使用备忘录，你的函数将重新创建，并占用一些内存和时间。箭头函数也将重新创建。

import React, { memo, useCallback } from "react";
import { Text, Button } from "react-native";

const ClearCustomButtom = memo(({ onPress, title }) => (
  <Button onPress={onPress}>
    <Text>{title}</Text>
  </Button>
));

const ExtraCustomButtom = memo(({ onPress, title, socketId }) => {
  const handlePress = () => {
    console.log("Some extra action");
    onPress(socketId);
  };

  return (
    <Button onPress={handlePress}>
      <Text>{title}</Text>
    </Button>
  );
});

const RequestCustomButtom = memo(({ url, title }) => {
  const handlePress = () => {
    //send request on server
  };

  return (
    <Button onPress={handlePress}>
      <Text>{title}</Text>
    </Button>
  );
});

export default function App() {
  //UseCallback create point for put in button props, not function but point. Without useCallback component will rerender every time.
  const handlePressClearDecline = useCallback(() => {}, []);

  const handlePressExtraDecline = useCallback((socketId) => {
    console.log(socketId);
  }, []);

  return (
    <>
      <ClearCustomButtom
        title="ClearCustomButton"
        onPress={handlePressClearDecline}
      />
      <ExtraCustomButtom
        title="ExtraCustomButton"
        onPress={handlePressExtraDecline}
        socketId="777"
      />
      <RequestCustomButtom title="Send request" />
    </>
  );
}

这是react-native中最常见的例子，如何编写可按组件。