App.js

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 *
 * @format
 * @flow strict-local
 */

import React from 'react';
import {
  SafeAreaView,
  StyleSheet,
  ScrollView,
  View,
  Text,
  TextInput,
  StatusBar,
  Button,
  Alert,
} from 'react-native';
let number = Math.round(Math.random() * 100);
let count = 0;
const App = () => {
  const [text, setText] = React.useState('');
  React.useEffect(() => {
    initNumber();
  }, []);
  function doGuess() {
    count++;
    const numberValue = parseInt(text);
    if (numberValue === number) {
      Alert.alert(`猜中了！猜了${count}次`);
      initNumber();
    } else if (numberValue < number) {
      Alert.alert('猜小了!');
    } else {
      Alert.alert('猜大了！');
    }
  }
  function initNumber() {
    number = Math.round(Math.random() * 100);
    count = 0;
  }
  return (
    <>
      <StatusBar barStyle="dark-content" />

      <SafeAreaView>
        <TextInput style={styles.input} value={text} onChangeText={setText} />
        <Button title="猜" onPress={doGuess} />
      </SafeAreaView>
    </>
  );
};

const styles = StyleSheet.create({
  input: {
    borderWidth: 2,
    borderColor: 'blue',
    margin: 120,
    height: 50,
    fontSize: 20,
    paddingLeft: 10,
  },
});

export default App;