在组件中读取和更新存储状态
在 React Native 组件中使用 useStore 钩子访问存储值和操作，并通过按钮点击或表单提交触发更新。
在组件中读取和更新存储状态 是 CoddyKit 上的免费 React Native Academy 课时。 这是第 2 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。
Connecting a Component to Zustand
Using a Zustand store in a component is as simple as calling the store hook at the top of the function. The hook is the same object returned by create. You can pass a selector to pick specific values, or read actions directly. No import of useSelector or useDispatch is required — the store hook handles everything.
import { useCounterStore } from '../stores/counterStore';
export default function CounterScreen() {
const count = useCounterStore((state) => state.count);
const increment = useCounterStore((state) => state.increment);
const decrement = useCounterStore((state) => state.decrement);
return (
<View style={styles.container}>
<Text style={styles.count}>{count}</Text>
<Button title='Increment' onPress={increment} />
<Button title='Decrement' onPress={decrement} />
</View>
);
}Selecting Multiple Values Efficiently
To read multiple values from a Zustand store without causing excessive re-renders, you have two options. You can call the store hook multiple times with individual selectors (each subscription is independent), or you can return an object and use the shallow equality helper to compare each property separately.
import { shallow } from 'zustand/shallow';
// Option 1: multiple hooks (preferred for 2-3 values)
const count = useCounterStore((s) => s.count);
const status = useCounterStore((s) => s.status);
// Option 2: shallow equality for multiple values at once
const { count, status } = useCounterStore(
(s) => ({ count: s.count, status: s.status }),
shallow
);Triggering Updates from Button Presses
Zustand actions are plain JavaScript functions, so you pass them directly to React Native event handlers like onPress. You do not need to dispatch an action object or call a helper — just call the function. This makes the component code cleaner and easier to read compared to the Redux dispatch pattern.
export default function TodoInput() {
const [text, setText] = React.useState('');
const addTodo = useTodoStore((state) => state.addTodo);
const handleAdd = () => {
if (text.trim()) {
addTodo(text.trim());
setText('');
}
};
return (
<View>
<TextInput value={text} onChangeText={setText} placeholder='New todo' />
<Button title='Add' onPress={handleAdd} />
</View>
);
}Reading Store State in a FlatList
Zustand stores work naturally with React Native's FlatList. Select the array from the store and pass it to the data prop. Zustand only re-renders this component when the array reference changes, which happens when your store action replaces or mutates the items array and returns a new reference via set.
export default function TodoList() {
const todos = useTodoStore((state) => state.todos);
const removeTodo = useTodoStore((state) => state.removeTodo);
return (
<FlatList
data={todos}
keyExtractor={(item) => item.id}
renderItem={({ item }) => (
<TouchableOpacity onPress={() => removeTodo(item.id)}>
<Text>{item.text}</Text>
</TouchableOpacity>
)}
/>
);
}Updating Nested State
When your store state has nested objects, pass a function to set and spread the nested level you want to update. Without spreading, set would replace the top-level key entirely, wiping out other nested properties. Alternatively, use the Immer middleware (covered in the previous lesson) to mutate nested values directly.
export const useProfileStore = create<ProfileStore>((set) => ({
profile: {
name: '',
bio: '',
avatar: null,
},
updateName: (name: string) =>
set((state) => ({ profile: { ...state.profile, name } })),
updateBio: (bio: string) =>
set((state) => ({ profile: { ...state.profile, bio } })),
}));Optimistic UI Updates
Optimistic updates improve perceived performance by updating the UI immediately when the user takes an action, before waiting for the server response. In Zustand, call set to update state immediately, then make the API call. If the API fails, call set again to revert the state to its previous value.
toggleLike: async (postId: string) => {
// Update UI immediately
set((state) => ({
posts: state.posts.map((p) =>
p.id === postId ? { ...p, liked: !p.liked } : p
),
}));
try {
await api.toggleLike(postId);
} catch {
// Revert on failure
set((state) => ({
posts: state.posts.map((p) =>
p.id === postId ? { ...p, liked: !p.liked } : p
),
}));
}
}Resetting Store State
A common pattern is to add a reset action that restores the store to its initial state. Store the initial state in a constant outside the create call and reference it in the reset action. This is useful for logout flows where you need to clear all user data from every store at once.
const initialState = { user: null, token: null, isLoggedIn: false };
export const useAuthStore = create<AuthStore>((set) => ({
...initialState,
login: (user, token) => set({ user, token, isLoggedIn: true }),
logout: () => set(initialState), // restore all fields to initial values
}));Watching Store Changes with subscribe
useStore.subscribe lets you react to store changes outside of React components — for example, writing to AsyncStorage whenever settings change, or logging analytics events when specific state transitions occur. Always unsubscribe in the cleanup function to avoid memory leaks.
useEffect(() => {
const unsubscribe = useSettingsStore.subscribe(
(state) => state.theme,
(theme) => {
console.log('Theme changed to:', theme);
AsyncStorage.setItem('theme', theme);
}
);
return unsubscribe; // cleanup on unmount
}, []);Sharing State Between Screens
Because Zustand stores live outside any component tree, they are perfect for sharing state between screens without prop drilling or React Navigation params. Screen A updates the store, Screen B reads from it — both see the same live state immediately. This is much simpler than passing data through route params for deep navigation hierarchies.
// ScreenA.tsx — writes to store
const setSelectedProduct = useProductStore((s) => s.setSelected);
<Button title='View Details' onPress={() => {
setSelectedProduct(product);
navigation.navigate('ProductDetail');
}} />
// ScreenB.tsx — reads from store
const product = useProductStore((s) => s.selected);Testing Zustand Store Actions
Testing a Zustand store is straightforward because it has no dependencies on React. Import the store, call actions directly on getState(), and assert the updated values. You can also reset the store between tests by calling the reset action or overwriting state with setState to ensure test isolation.
import { useCounterStore } from '../counterStore';
before Each(() => {
useCounterStore.getState().reset();
});
test('increment increases count by 1', () => {
useCounterStore.getState().increment();
expect(useCounterStore.getState().count).toBe(1);
});
test('reset brings count back to 0', () => {
useCounterStore.setState({ count: 5 });
useCounterStore.getState().reset();
expect(useCounterStore.getState().count).toBe(0);
});Form State with Zustand
Zustand can manage form state that needs to be shared between multiple screens in a multi-step form flow. Store field values and a current step number in the store, and let each screen read and update only its own fields. On final submission, access the complete form data from getState() in the submit handler.
export const useFormStore = create<FormStore>((set) => ({
step: 1,
name: '',
email: '',
password: '',
setField: (field, value) => set({ [field]: value }),
nextStep: () => set((state) => ({ step: state.step + 1 })),
reset: () => set({ step: 1, name: '', email: '', password: '' }),
}));Quick Check
Test your understanding of React Native Mobile Development concepts from this lesson.
Lesson Recap
In this lesson you learned: calling the store hook with a selector efficiently subscribes a component to only the state it needs, Zustand actions are plain functions that you pass directly to event handlers, and store.subscribe enables side effects like caching or analytics outside the React lifecycle. Next up we explore persisting Zustand state with AsyncStorage.
常见问题解答
「在组件中读取和更新存储状态」课时是免费的吗？
是的 — 「在组件中读取和更新存储状态」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。
「在组件中读取和更新存储状态」这节课中我会学到什么？
在 React Native 组件中使用 useStore 钩子访问存储值和操作，并通过按钮点击或表单提交触发更新。 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 2 节课，共 4 节。
「在组件中读取和更新存储状态」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。