React Native Modal Modal Similar to Alert Way
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React Native Modal
Modal • Similar to Alert • Way to present information above an enclosing view.
Example 1 import React, { use. State } from "react"; import { Alert, Modal, Style. Sheet, Text, Touchable. Highlight, View } from "react-native";
Example 1, page 2 The animation. Type prop controls how the modal animates. const App = () => { slides in from the bottom fades into view const [modal. Visible, set. Modal. Visible] = use. State(false); none appears without an animation return ( <View style={styles. centered. View}> Default is set to none. <Modal animation. Type="slide" transparent={true} The transparent prop determines whether your modal will fill the entire view. Setting visible={modal. Visible} this to true will render the modal over a on. Request. Close={() => { transparent background. Alert. alert("Modal has been closed. "); The visible prop determines whether your modal is }} visible. > The on. Request. Close callback is called when the user taps the hardware back button on Android or the menu button on Apple TV.
Example 1, page 3 <View style={styles. centered. View}> <View style={styles. modal. View}> <Text style={styles. modal. Text}>Hello World!</Text> <Touchable. Highlight style={{. . . styles. open. Button, background. Color: "#2196 F 3" }} on. Press={() => { set. Modal. Visible(!modal. Visible); }} > <Text style={styles. text. Style}>Hide Modal</Text> </Touchable. Highlight> </View> </Modal> End tag for the modal component All of this is inside the Modal component and will be displayed when the Modal is displayed
Example 1, page 4 <Touchable. Highlight style={styles. open. Button} on. Press={() => { set. Modal. Visible(true); Causes the Modal to become visible }} > <Text style={styles. text. Style}>Show Modal</Text> </Touchable. Highlight> </View> ); };
Example 1, page 5 const styles = Style. Sheet. create({ centered. View: { flex: 1, justify. Content: "center", align. Items: "center", margin. Top: 22 }, Styles used in the app modal. View: { margin: 20, background. Color: "white", border. Radius: 20, padding: 35, align. Items: "center", shadow. Color: "#000", shadow. Offset: { width: 0, height: 2 }, shadow. Opacity: 0. 25, shadow. Radius: 3. 84, elevation: 5 }, open. Button: { background. Color: "#F 194 FF", border. Radius: 20, padding: 10, elevation: 2 }, text. Style: { color: "white", font. Weight: "bold", text. Align: "center" }, modal. Text: { margin. Bottom: 15, text. Align: "center" } });
Async • Async. Storage is an unencrypted, asynchronous, persistent, key-value storage system that is global to the app. • Async. Storage operates globally. • On i. OS, Async. Storage is backed by native code that stores small values in a serialized dictionary and larger values in separate files. • On Android, Async. Storage will use either Rocks. DB or SQLite based on what is available.
Async storage • https: //github. com/react-native-async-storage/async-storage • This is the github repo • https: //react-native-async-storage. github. io/asyncstorage/docs/usage • Usage docs
Async storage • Async Storage can only store string data, • in order to store object data you need to serialize it first. • For data that can be serialized to JSON you can use JSON. stringify() when saving the data • use JSON. parse() when loading the data.
JSON • JSON: Java. Script Object Notation. • JSON is a syntax for storing and exchanging data. • JSON is text, written with Java. Script object notation. • See W 3 Schools: https: //www. w 3 schools. com/js/js_json_intro. asp
Functions: get. Item • Gets a string value for given key. This function can either return a string value for existing key or return null otherwise. • In order to store object value, you need to deserialize it, e. g. using JSON. parse(). static get. Item(key: string, [callback]: ? (error: ? Error, result: ? string) => void): Promise Returns: • Promise resolving with a string value, if entry exists for given key, or null otherwise. • Promise can also be rejected in case of underlying storage error.
Functions: get. Item get. My. String. Value = async () => { try { return await Async. Storage. get. Item('@key') } catch(e) { // read error The key that you stored. You are storing a key: value pair } In this case ‘@key’ is the key console. log('Done. ') }
Functions: get. Item (for an object) const get. Data = async () => { try { const json. Value = await Async. Storage. get. Item('@storage_Key') return json. Value != null ? JSON. parse(json. Value) : null; } catch(e) { // error reading value } }
Functions: set. Item • Sets a string value for given key. This operation can either modify an existing entry, if it did exist for given key, or add new one otherwise. • In order to store object value, you need to serialize it, e. g. using JSON. stringify() static set. Item(key: string, value: string, [callback]: ? (error: ? Error) => void): Promise Returns: • Promise resolving when the set operation is completed. • Promise can also be rejected in case of underlying storage error.
Functions: set. Item set. String. Value = async (value) => { try { await Async. Storage. set. Item('key', value) } catch(e) { Can be any unique string // save error You are storing a key: value pair In this case ‘key’ is the key } And value is the value console. log('Done. ') }
Functions: set. Item (for an object) const store. Data = async (value) => { try { const json. Value = JSON. stringify(value) await Async. Storage. set. Item('@storage_Key', json. Value) } catch (e) { // saving error } }
Functions: remove. Item • Removes item for a key, invokes (optional) callback once completed. static remove. Item(key: string, [callback]: ? (error: ? Error) => void): Promise Returns: • Promise object.
Functions: remove. Item remove. Value = async () => { try { await Async. Storage. remove. Item('@My. App_key') } catch(e) { // remove error } console. log('Done. ') }
Functions: clear • Removes whole Async. Storage data, for all clients, libraries, etc. • You probably want to use remove. Item or multi. Remove to clear only your App's keys. static clear([callback]: ? (error: ? Error) => void): Promise Returns: • Promise object.
Functions: clear. All = async () => { try { await Async. Storage. clear() } catch(e) { // clear error } console. log('Done. ') }
Other methods • https: //react-native-async-storage. github. io/async-storage/docs/api
Installing • This is a community library, so must install: yarn add @react-native-community/async-storage • or npm install @react-native-community/async-storage
Import import React, {use. State} from 'react'; import { Alert, Style. Sheet, Text, View, Touchable. Highlight, Text. Input, Button } from 'react-native'; import { Async. Storage } from 'react-native';
Example export default function App () { [my. State, set. State] = use. State(”George"); const store. Data = async (value) => { try { await Async. Storage. set. Item('@storage_Key', value) } catch (e) { // saving error Can be any unique string You are storing a key: value pair } In this case @storage_Key is the key } And value is the value
Example const get. Data = async () => { try { const value = await Async. Storage. get. Item('@storage_Key') if(value !== null) { // value previously stored Alert. alert("got value " + value); } } catch(e) { // error reading value } }
Example const _put. In. Storage = () => { Alert. alert('You stored ' + my. State); store. Data(my. State); } const _get. From. Storage = () => { get. Data(); }
Example return ( <View style={styles. container}> <Text. Input style={{flex: 1}} style={{height: 40}} placeholder='Enter a name' <Text>From store: {my. State}</Text> <Button style={{margin. Bottom: 100}} on. Press={_get. From. Storage } title='Get from storage' /> on. Change. Text={(text) => set. State(text)} /> <Button style={{margin. Bottom: 100}} on. Press={_put. In. Storage } title='Store' /> } </View> );
Example const styles = Style. Sheet. create({ container: { flex: 1, background. Color: '#F 5 FCFF', align. Items: 'center', justify. Content: 'center', margin. Top: 100, }, row: { font. Size: 24, • padding: 42, • border. Width: 1, border. Color: "#DDDDDD", background. Color: '#BB 3333', } });
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