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TextInput 基础与键盘类型

渲染 TextInput，使用 onChangeText 将其绑定到状态，针对电子邮件或数字输入配置键盘类型，并处理回车键事件。

TextInput 基础与键盘类型 是 CoddyKit 上的免费 React Native Academy 课时。 这是第 1 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 React Native Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 React Native Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

The TextInput Component

TextInput is the React Native component for capturing keyboard input from users. It renders as a native text field on both iOS and Android, giving users the platform's native typing experience including autocorrect, predictive text, and system keyboard shortcuts. Import it from react-native and use it for any input that requires a keyboard: search boxes, login forms, settings fields, and chat message composers. Without styling, TextInput has no visible border on iOS — always style it to make it visible to users.

import { TextInput, View, StyleSheet } from 'react-native';
import { useState } from 'react';

export default function BasicInput() {
  const [text, setText] = useState('');

  return (
    <View style={{ padding: 16 }}>
      <TextInput
        value={text}
        onChangeText={setText}
        placeholder='Type something here...'
        style={styles.input}
      />
    </View>
  );
}

const styles = StyleSheet.create({
  input: {
    borderWidth: 1,
    borderColor: '#ccc',
    borderRadius: 10,
    paddingHorizontal: 14,
    paddingVertical: 12,
    fontSize: 16,
    backgroundColor: '#fff',
  },
});

onChangeText vs onChange

The onChangeText callback is the most common way to react to text input. It receives the new text string directly as its argument, making it easy to pass to a useState setter: onChangeText={setText}. The lower-level onChange callback receives a full event object (event.nativeEvent.text) — useful when you also need other event metadata like cursor position. For most use cases, onChangeText is simpler and preferred. Use onChange only when you need the native event details.

import { TextInput } from 'react-native';
import { useState } from 'react';

function TextInputExample() {
  const [text, setText] = useState('');

  return (
    <>
      {/* Simple: receives the string directly */}
      <TextInput
        onChangeText={(newText) => setText(newText)}
        // shorthand equivalent:
        // onChangeText={setText}
      />

      {/* Advanced: receives the full event object */}
      <TextInput
        onChange={(event) => {
          console.log('text:', event.nativeEvent.text);
          console.log('selection:', event.nativeEvent.selection);
        }}
      />
    </>
  );
}

Keyboard Types for Different Input

The keyboardType prop controls which keyboard variant the OS displays. For a numeric input, 'numeric' shows a numpad. For emails, 'email-address' includes the @ and . keys prominently. 'phone-pad' shows the phone dialer layout. 'decimal-pad' is like numeric but includes a decimal point. 'url' shows / and .com shortcuts. Using the correct keyboard type is a usability win — it reduces the keystrokes needed to enter data and prevents users from typing invalid characters.

import { View, TextInput, Text, StyleSheet } from 'react-native';

export default function KeyboardTypesDemo() {
  return (
    <View style={{ padding: 16, gap: 12 }}>
      <TextInput style={styles.input} keyboardType='default' placeholder='Default text' />
      <TextInput style={styles.input} keyboardType='email-address' placeholder='email@example.com' />
      <TextInput style={styles.input} keyboardType='numeric' placeholder='Enter a number' />
      <TextInput style={styles.input} keyboardType='phone-pad' placeholder='Phone number' />
      <TextInput style={styles.input} keyboardType='decimal-pad' placeholder='Price (0.00)' />
      <TextInput style={styles.input} keyboardType='url' placeholder='https://...' />
    </View>
  );
}

const styles = StyleSheet.create({
  input: { borderWidth: 1, borderColor: '#ccc', borderRadius: 8, padding: 12, fontSize: 16, backgroundColor: '#fff' },
});

Secure Text Entry for Passwords

For password fields, set secureTextEntry={true} to hide the typed characters with bullet points. This is essential for any field containing sensitive data — passwords, PINs, security codes. You can add a show/hide password toggle by managing a showPassword boolean in state and toggling secureTextEntry. Also set autoCapitalize='none' and autoCorrect={false} on password fields — you don't want autocorrect or capital letters changing a user's password as they type.

import { TextInput, TouchableOpacity, Text, View, StyleSheet } from 'react-native';
import { useState } from 'react';

export default function PasswordInput() {
  const [password, setPassword] = useState('');
  const [visible, setVisible] = useState(false);

  return (
    <View style={styles.wrapper}>
      <TextInput
        value={password}
        onChangeText={setPassword}
        secureTextEntry={!visible}
        autoCapitalize='none'
        autoCorrect={false}
        placeholder='Password'
        style={styles.input}
      />
      <TouchableOpacity
        style={styles.toggle}
        onPress={() => setVisible(v => !v)}
      >
        <Text style={{ fontSize: 18 }}>{visible ? '🙈' : '👁'}</Text>
      </TouchableOpacity>
    </View>
  );
}

const styles = StyleSheet.create({
  wrapper: { flexDirection: 'row', alignItems: 'center', borderWidth: 1, borderColor: '#ccc', borderRadius: 10, paddingHorizontal: 14 },
  input: { flex: 1, paddingVertical: 12, fontSize: 16 },
  toggle: { paddingLeft: 8 },
});

autoCapitalize and autoCorrect

autoCapitalize controls when the OS capitalizes the first letter. Values: 'none' (never capitalize), 'sentences' (first letter of each sentence, default), 'words' (first letter of each word), 'characters' (every character). Use 'none' for usernames, email addresses, and passwords. Use 'words' for name fields. autoCorrect={false} disables autocorrect entirely, which is essential for usernames, technical terms, or any field where the user knows what they're typing.

import { View, TextInput, StyleSheet } from 'react-native';

export default function FormInputs() {
  return (
    <View style={{ padding: 16, gap: 12 }}>
      {/* Name: capitalize each word, allow autocorrect */}
      <TextInput
        style={styles.input}
        placeholder='Full name'
        autoCapitalize='words'
        autoCorrect={true}
      />
      {/* Username: no caps, no autocorrect */}
      <TextInput
        style={styles.input}
        placeholder='@username'
        autoCapitalize='none'
        autoCorrect={false}
      />
      {/* Email: no caps, no autocorrect */}
      <TextInput
        style={styles.input}
        placeholder='Email address'
        keyboardType='email-address'
        autoCapitalize='none'
        autoCorrect={false}
      />
    </View>
  );
}

const styles = StyleSheet.create({
  input: { borderWidth: 1, borderColor: '#ccc', borderRadius: 8, padding: 12, fontSize: 16 },
});

returnKeyType and onSubmitEditing

The returnKeyType prop changes the label on the keyboard's Return key: 'done', 'go', 'next', 'search', 'send'. Use 'next' to indicate that pressing Return moves to the next field. The onSubmitEditing callback fires when the user presses the Return key. Combine returnKeyType='next' with onSubmitEditing to programmatically focus the next TextInput using a ref — this creates a smooth, tab-like navigation between form fields that users expect on mobile.

import { View, TextInput, StyleSheet, useRef } from 'react-native';

export default function MultiFieldForm() {
  const emailRef = useRef(null);
  const passwordRef = useRef(null);

  return (
    <View style={{ padding: 16, gap: 12 }}>
      <TextInput
        ref={emailRef}
        style={styles.input}
        placeholder='Email'
        keyboardType='email-address'
        returnKeyType='next'
        onSubmitEditing={() => passwordRef.current?.focus()}
      />
      <TextInput
        ref={passwordRef}
        style={styles.input}
        placeholder='Password'
        secureTextEntry
        returnKeyType='done'
        onSubmitEditing={() => console.log('Form submitted!')}
      />
    </View>
  );
}

const styles = StyleSheet.create({
  input: { borderWidth: 1, borderColor: '#ccc', borderRadius: 8, padding: 12, fontSize: 16 },
});

Multiline TextInput

For multi-line text like a bio, message, or comment, add the multiline prop. The TextInput will expand as the user types new lines and support newline characters. Use numberOfLines on Android to set the initial height (iOS auto-sizes). The textAlignVertical: 'top' style (Android only) prevents text from starting at the vertical center of the input box. On iOS, multiline inputs grow to fit their content automatically when there's no explicit height set. Combine maxLength with a character counter display for message composer fields.

import { TextInput, Text, View, StyleSheet } from 'react-native';
import { useState } from 'react';

export default function BioInput() {
  const [bio, setBio] = useState('');
  const MAX_LENGTH = 200;

  return (
    <View style={{ padding: 16 }}>
      <TextInput
        value={bio}
        onChangeText={setBio}
        placeholder='Tell us about yourself...'
        multiline
        numberOfLines={4}     // Android: initial height
        maxLength={MAX_LENGTH}
        style={styles.input}
        textAlignVertical='top' // Android: align text to top
      />
      <Text style={styles.counter}>
        {bio.length}/{MAX_LENGTH}
      </Text>
    </View>
  );
}

const styles = StyleSheet.create({
  input: { borderWidth: 1, borderColor: '#ccc', borderRadius: 10, padding: 12, fontSize: 15, minHeight: 100 },
  counter: { textAlign: 'right', color: '#999', fontSize: 12, marginTop: 4 },
});

Focus, Blur, and onFocus / onBlur Events

TextInput fires onFocus when the user taps into it (keyboard appears) and onBlur when they tap away (keyboard hides). Use these to show/hide helper text, change the border color to indicate active state, or trigger field-level validation. A common pattern is to validate a field only after the user has left it (on blur), not while they are still typing — this avoids showing error messages before the user finishes typing. Track which field is focused with a state variable if you need to style multiple inputs differently based on focus.

import { TextInput, View, StyleSheet } from 'react-native';
import { useState } from 'react';

export default function FocusableInput({ placeholder, onBlurValidate }) {
  const [focused, setFocused] = useState(false);
  const [value, setValue] = useState('');
  const [error, setError] = useState('');

  function handleBlur() {
    setFocused(false);
    const err = onBlurValidate ? onBlurValidate(value) : '';
    setError(err);
  }

  return (
    <View>
      <TextInput
        value={value}
        onChangeText={setValue}
        onFocus={() => setFocused(true)}
        onBlur={handleBlur}
        placeholder={placeholder}
        style={[
          styles.input,
          focused && styles.focused,
          error && styles.error,
        ]}
      />
    </View>
  );
}

const styles = StyleSheet.create({
  input: { borderWidth: 1.5, borderColor: '#ddd', borderRadius: 10, padding: 12, fontSize: 16 },
  focused: { borderColor: '#4f86f7', shadowColor: '#4f86f7', shadowOpacity: 0.2, shadowRadius: 4, shadowOffset: { width: 0, height: 2 } },
  error: { borderColor: '#e74c3c' },
});

Dismissing the Keyboard

On mobile, the keyboard doesn't dismiss automatically when users tap outside a TextInput. Use Keyboard.dismiss() from react-native to programmatically hide it. Wrap your screen content in a TouchableWithoutFeedback that calls Keyboard.dismiss() on press, so tapping anywhere outside the keyboard dismisses it. Alternatively, use the keyboardDismissMode prop on ScrollView: 'on-drag' dismisses the keyboard when the user starts scrolling, which is a comfortable mobile UX pattern.

import { TouchableWithoutFeedback, Keyboard, ScrollView, TextInput, StyleSheet, View } from 'react-native';

export default function DismissibleForm() {
  return (
    <TouchableWithoutFeedback onPress={Keyboard.dismiss} accessible={false}>
      <ScrollView
        style={{ flex: 1 }}
        keyboardDismissMode='on-drag'  // dismiss on scroll
        keyboardShouldPersistTaps='handled'
      >
        <View style={{ padding: 16, gap: 12 }}>
          <TextInput style={styles.input} placeholder='Name' />
          <TextInput style={styles.input} placeholder='Email' keyboardType='email-address' />
          <TextInput style={styles.input} placeholder='Message' multiline numberOfLines={4} textAlignVertical='top' />
        </View>
      </ScrollView>
    </TouchableWithoutFeedback>
  );
}

const styles = StyleSheet.create({
  input: { borderWidth: 1, borderColor: '#ccc', borderRadius: 8, padding: 12, fontSize: 16 },
});

KeyboardAvoidingView

When the keyboard appears, it covers the bottom of the screen and can hide text inputs in forms. Wrap your screen in KeyboardAvoidingView to automatically push the content up when the keyboard opens. Set behavior='padding' on iOS and behavior='height' on Android (use Platform.OS to pick the right value). Pair it with keyboardVerticalOffset to account for the header height. For screens with many inputs, combining KeyboardAvoidingView with a ScrollView inside provides the best experience.

import { KeyboardAvoidingView, Platform, ScrollView, TextInput, TouchableOpacity, Text, StyleSheet } from 'react-native';

export default function LoginScreen() {
  return (
    <KeyboardAvoidingView
      style={{ flex: 1 }}
      behavior={Platform.OS === 'ios' ? 'padding' : 'height'}
      keyboardVerticalOffset={60} // adjust for header height
    >
      <ScrollView contentContainerStyle={styles.form}>
        <TextInput style={styles.input} placeholder='Email' keyboardType='email-address' />
        <TextInput style={styles.input} placeholder='Password' secureTextEntry />
        <TouchableOpacity style={styles.btn}>
          <Text style={styles.btnText}>Log In</Text>
        </TouchableOpacity>
      </ScrollView>
    </KeyboardAvoidingView>
  );
}

const styles = StyleSheet.create({
  form: { padding: 24, gap: 16, flexGrow: 1, justifyContent: 'center' },
  input: { borderWidth: 1, borderColor: '#ccc', borderRadius: 10, padding: 14, fontSize: 16 },
  btn: { backgroundColor: '#4f86f7', padding: 16, borderRadius: 10, alignItems: 'center' },
  btnText: { color: '#fff', fontWeight: 'bold', fontSize: 16 },
});

Input Masking for Formatted Values

Some inputs need formatted display as the user types — credit card numbers with spaces every 4 digits, phone numbers with dashes, or dates in DD/MM/YYYY format. Implement this in the onChangeText handler: strip formatting characters from the raw input, apply the format, and set the formatted string as state. The TextInput shows the formatted value (from state), but you store the raw digits separately for submission. Libraries like react-native-mask-input provide a drop-in masked TextInput that handles common patterns automatically.

import { TextInput } from 'react-native';
import { useState } from 'react';

// Manual phone number formatting: (555) 123-4567
export default function PhoneInput({ onPhoneChange }) {
  const [display, setDisplay] = useState('');

  function formatPhone(raw) {
    const digits = raw.replace(/\D/g, '').slice(0, 10); // digits only, max 10
    let formatted = digits;
    if (digits.length > 6) {
      formatted = '(' + digits.slice(0,3) + ') ' + digits.slice(3,6) + '-' + digits.slice(6);
    } else if (digits.length > 3) {
      formatted = '(' + digits.slice(0,3) + ') ' + digits.slice(3);
    } else if (digits.length > 0) {
      formatted = '(' + digits;
    }
    setDisplay(formatted);
    onPhoneChange(digits); // pass raw digits to parent
  }

  return (
    <TextInput
      value={display}
      onChangeText={formatPhone}
      keyboardType='phone-pad'
      placeholder='(555) 123-4567'
      style={{ borderWidth: 1, borderColor: '#ccc', borderRadius: 8, padding: 12, fontSize: 16 }}
    />
  );
}

Quick Check

Test your understanding of React Native Mobile Development concepts from this lesson.

Lesson Recap

In this lesson you learned: keyboardType shows the appropriate keyboard for the data type, returnKeyType with refs enables tab-like navigation between form fields, and KeyboardAvoidingView prevents the keyboard from covering input fields at the bottom of the screen. Next up we explore adding tap feedback with TouchableOpacity and Pressable.

常见问题解答

「TextInput 基础与键盘类型」课时是免费的吗？

是的 — 「TextInput 基础与键盘类型」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 React Native Academy 课程的其余内容，请升级到 CoddyKit PRO。 React Native Academy 课程共包含 4 节课。

「TextInput 基础与键盘类型」这节课中我会学到什么？

渲染 TextInput，使用 onChangeText 将其绑定到状态，针对电子邮件或数字输入配置键盘类型，并处理回车键事件。 你通过在浏览器中直接运行的动手代码来练习 React Native Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 React Native Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 React Native Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 1 节课，共 4 节。

「TextInput 基础与键盘类型」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 React Native Academy 课中编写并运行代码吗？

能。每节 React Native Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

此课程中的所有课时

  1. TextInput 基础与键盘类型
  2. 使用 TouchableOpacity 与 Pressable 处理点击
  3. 切换按钮、开关与复选框
  4. 构建简单的登录表单
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