What are the importance of Liquidity in Cryptocurrency Exchanges?

What is Liquidity?

In General, Liquidity is the effective exchange of assets into cash without affecting the price of the asset. When it comes to Cryptocurrency Exchange, we need to consider two major factors like Speed and the price variation as every trader wants to executive fast and cost effective trade.

In the Context of Crypto Trading, Liquidity is differentiate in three aspects

Asset Liquidity - The function between buyer and seller for the desired asset

Exchange Liquidity - The overall function of traders in the Cryptocurrency Exchange

Market Liquidity - The overall health of the market

Crypto traders need to evaluate all the above three liquidity before proceeding with trading, so that they can spot the perfect asset and the perfect time for trading.

Why is Liquidity Important in Cryptocurrency Exchange?
Liquidity is always the indispensible factor in finance and no doubt that good liquidity could automatically build trust among traders in the market

Stability

Liquidity increases the stability and prevents traders and cryptocurrency exchagnes from market fluctuations. The influence of big market players does not affect the asset. For instance, Buying and selling of Bitcoin in bulk could have a minimum impact on the price of the bitcoin but in the case of other altcoins, bulk trading could affect the price of the altcoin. The added advantage in Stability is prediction. Traders can predict the market price in the future.

Fair Price

Good Liquidity insures fair and equal price for market participants. The reason behind the fair price is the huge volume of buyers and sellers. The asset with high trading activity lets sellers sell it at a competitive price and buyers naturally stick to it. Thus created the stable equilibrium which is much important for the good market

Fast Transaction

High Liquidity is also the sign of more number of traders so that the buy order as well as the sell order would fill out faster than in the low liquidity environment. This obviously increases the trading speed which enriches the user experience.

Accuracy for Technical Analysis

The more good the data, the more accurate the prediction. Thus Liquidity gives a huge volume of data for precise calculation

Factors Affecting Liquidity
Trade Volume

Cryptocurrency Exchanges

Acceptance

Rules and Regulations and more.

Know more about Importance of Liquidity in Cryptocurrency exchange here !!

To launch cryptocurrency exchange with high liquidity, contact best cryptocurrency exchange script provider who provide liquidity solutions for your crypto exchange.

#liquidity #cryptocurrencyexchangescript

What is GEEK

Buddha Community

関数をC++からReactNativeにエクスポートする方法

今日も、ネイティブモジュールとC++での経験を共有し続けています。

多くのC/C ++ライブラリがモバイルプラットフォーム用に作成されているので、それらをiOSまたはReactNativeアプリケーションに実装する必要があります。そのため、関数をC++からReactNativeにエクスポートする方法についての記事を書きたいと思います。これは、理解しやすく、初心者の時間を節約できます。新しいreactネイティブアプリケーションから始めます

1.新しいreactネイティブアプリを作成し、ターミナルを開いて実行します

npx react-native init NativeModules

2. Xcodeを開き、NativeModules / ios/NativeModule.xcworkspaceに移動します

3.C++側での作業

新しいC++ファイルを作成し、名前を付けますCpp_to_RN.cpp

新しいC++ファイルを作成すると、XcodeはヘッダーファイルCpp_to_RN.hpp を作成します

まず、「Cpp_to_RN.hpp」ファイルを開き、本体のない関数を含むクラスを作成します。

#ifndef Cpp_to_RN_hpp
#define Cpp_to_RN_hpp#include <stdio.h>
#include <string>class Cpp_to_RN {
public:
    std::string sayHello();
};#endif /* Cpp_to_RN_hpp */

次に、ファイルを開いてCpp_to_RN.cpp、単純な関数「sayHello()」を記述します。

#include "Cpp_to_RN.hpp"
std::string Cpp_to_RN::sayHello(){
    return "Hello from CPP";
}

4.C++ファイルのラッピングに取り組んでいます。

C ++ファイルをラップしてIOS（swift）側にエクスポートするには

a。ObjectiveCファイルを作成して名前を付けますCpp_to_RN.m

名前をに変更Cpp_to_RN.m します Cpp_to_RN.mm

b。ファイルを開き、C++ファイルからWrapCpp_to_RN.mm 関数をラップする本文のコンテンツを記述します。sayHello

#import <Foundation/Foundation.h>
#import "WrapCpp_to_RN.h"
#import "Cpp_to_RN.hpp"@implementation WrapCpp_to_RN- (NSString *) sayHello {
  Cpp_to_RN fromCPP;
    std::string helloWorldMessage = fromCPP.sayHello();
    return [NSString
            stringWithCString:helloWorldMessage.c_str()
            encoding:NSUTF8StringEncoding];
}
@end

c。ヘッダーファイルを作成し、名前を付けますWrapCpp_to_RN.h

wrapSayHello関数をSwiftファイルにエクスポートします

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

5. iOS（Swift）側での作業

C++関数をReactNativeにエクスポートするには

a。Swiftファイルを作成し、名前を付けますSendCpp_to_RN.swift

注：Xcodeは、NativeModules-Bridging-Header.hファイルを作成するように要求します。

クラスSendCpp_to_RNを作成し、次のように宣言しますNSObject

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

requiresMainQueueSetup()アプリケーション実行時の警告を防ぐ関数を作成する

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

WrapCpp_to_RN()fromをラップする関数を記述しますWrapCpp_to_RN.mm

import Foundation@objc(SendCpp_to_RN)
class SendCpp_to_RN : NSObject {
    
  @objc static func requiresMainQueueSetup() -> Bool {
        return false
    }
  
  @objc func fromCpp(_ successCallback: RCTResponseSenderBlock) -> Void {
    successCallback([NSNull(), WrapCpp_to_RN().wrapSayHello() as Any])
    }}

b。Swiftファイルのラップ関数をReactNativeにエクスポートします

を使用してSwiftクラスとその関数をエクスポートするObjectiveCファイルを作成しますCallback

#import <React/RCTBridgeModule.h>
#import <Foundation/Foundation.h>
#import "UIKit/UIKit.h"
@interface RCT_EXTERN_MODULE(SendCpp_to_RN, NSObject)RCT_EXTERN_METHOD(fromCpp:(RCTResponseSenderBlock)successCallback)@end

c。SwiftをReactNativeに接続し、NativeModules-Bridging-Header.h ファイルを開きます

#import <React/RCTBridgeModule.h>#import <React/RCTViewManager.h>#import "WrapCpp_to_RN.h"

6.ReactNative側での作業

Swiftクラスとその関数を呼び出す

import React from 'react';
import {StyleSheet, Text, View, NativeModules, Button} from 'react-native';const App = () => {
  const onPress = () => {
    const {SendCpp_to_RN} = NativeModules;
    SendCpp_to_RN.fromCpp((_err, res) => console.log(res));
  };
  return (
    <View style={styles.container}>
      <Text> Practice !</Text>
      <Button title="C++ to React Native" color="#841584" onPress={onPress} />
    </View>
  );
};
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});
export default App;

これで完了です。アプリケーションを実行するだけです。

react-native run-ios

または、Xcodeの「実行」ボタンをクリックして、実行内容を確認してください。

私の記事がお役に立てば幸いです。お読みいただきありがとうございます。

 ソース：https ：//betterprogramming.pub/native-modules-export-c-function-to-react-native-for-beginners-77e89934b210

#cpp #cplusplus #react 

Comment Exporter Une Fonction De C++ Vers React Native

Aujourd'hui, je continue à partager mon expérience avec le module natif et C++.

Comme nous verrons beaucoup de bibliothèques C/C++ écrire pour les plates-formes mobiles, nous devons les implémenter dans notre application iOS ou React Native. C'est pourquoi je souhaite écrire un article sur la façon d'exporter une fonction de C++ vers React Native, ce qui est facile à comprendre et fait gagner du temps aux débutants. Je vais commencer avec une nouvelle application native réactive

1. Créez une nouvelle application native React, ouvrez votre terminal et exécutez

npx react-native init NativeModules

2. Ouvrez Xcode et accédez à NativeModules/ios/NativeModule.xcworkspace

3. Travailler du côté C++

Créez un nouveau fichier C++ et nommez-leCpp_to_RN.cpp

Lorsque nous créons un nouveau fichier C++, Xcode créera un fichier d'en-tête Cpp_to_RN.hpp pour nous

Tout d'abord, ouvrez le fichier " Cpp_to_RN.hpp" et créez une classe qui inclut une fonction sans le corps.

#ifndef Cpp_to_RN_hpp
#define Cpp_to_RN_hpp#include <stdio.h>
#include <string>class Cpp_to_RN {
public:
    std::string sayHello();
};#endif /* Cpp_to_RN_hpp */

Ouvrez ensuite le Cpp_to_RN.cppfichier et écrivez une fonction simple " sayHello()"

#include "Cpp_to_RN.hpp"
std::string Cpp_to_RN::sayHello(){
    return "Hello from CPP";
}

4. Travail sur l'encapsulation du fichier C++.

Pour envelopper les fichiers C++ et les exporter vers le côté IOS (swift)

un. Créez un fichier Objective C et nommez-leCpp_to_RN.m

Renommez le Cpp_to_RN.m en Cpp_to_RN.mm

b. Ouvrez le WrapCpp_to_RN.mm fichier et écrivez le contenu du corps qui encapsulera la fonction sayHelloà partir du fichier C++.

#import <Foundation/Foundation.h>
#import "WrapCpp_to_RN.h"
#import "Cpp_to_RN.hpp"@implementation WrapCpp_to_RN- (NSString *) sayHello {
  Cpp_to_RN fromCPP;
    std::string helloWorldMessage = fromCPP.sayHello();
    return [NSString
            stringWithCString:helloWorldMessage.c_str()
            encoding:NSUTF8StringEncoding];
}
@end

c. Créez un fichier d'en-tête et nommez-leWrapCpp_to_RN.h

Exporter la wrapSayHellofonction vers le fichier Swift

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

5. Travailler du côté iOS (Swift)

Pour exporter la fonction C++ vers React Native

un. Créez un fichier Swift et nommez-leSendCpp_to_RN.swift

Remarque : Xcode nous demandera de créer un NativeModules-Bridging-Header.hfichier pour nous.

Créez une classe SendCpp_to_RNet déclarez-la commeNSObject

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Écrire une fonction requiresMainQueueSetup()pour empêcher l'avertissement lorsque nous exécutons l'application

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Ecrire une fonction pour envelopper le WrapCpp_to_RN()fromWrapCpp_to_RN.mm

import Foundation@objc(SendCpp_to_RN)
class SendCpp_to_RN : NSObject {
    
  @objc static func requiresMainQueueSetup() -> Bool {
        return false
    }
  
  @objc func fromCpp(_ successCallback: RCTResponseSenderBlock) -> Void {
    successCallback([NSNull(), WrapCpp_to_RN().wrapSayHello() as Any])
    }}

b. Exporter une fonction wrap dans un fichier Swift vers React Native

Créez un fichier Objective C pour exporter la classe Swift et sa fonction à l'aide deCallback

#import <React/RCTBridgeModule.h>
#import <Foundation/Foundation.h>
#import "UIKit/UIKit.h"
@interface RCT_EXTERN_MODULE(SendCpp_to_RN, NSObject)RCT_EXTERN_METHOD(fromCpp:(RCTResponseSenderBlock)successCallback)@end

c. Connectez Swift à React Native, ouvrez le NativeModules-Bridging-Header.h fichier

#import <React/RCTBridgeModule.h>#import <React/RCTViewManager.h>#import "WrapCpp_to_RN.h"

6. Travailler du côté React Native

Appelez la classe Swift et ses fonctions

import React from 'react';
import {StyleSheet, Text, View, NativeModules, Button} from 'react-native';const App = () => {
  const onPress = () => {
    const {SendCpp_to_RN} = NativeModules;
    SendCpp_to_RN.fromCpp((_err, res) => console.log(res));
  };
  return (
    <View style={styles.container}>
      <Text> Practice !</Text>
      <Button title="C++ to React Native" color="#841584" onPress={onPress} />
    </View>
  );
};
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});
export default App;

Et nous avons terminé, il suffit de lancer l'application

react-native run-ios

Ou cliquez simplement sur le bouton "exécuter" sur Xcode et voyez ce que nous avons fait.

J'espère que mon article vous sera utile, merci pour le temps de lecture.

 Source : https://betterprogramming.pub/native-modules-export-c-function-to-react-native-for-beginners-77e89934b210

#cpp #cplusplus #react 

Cómo Exportar Una Función De C++ A React Native

Hoy sigo compartiendo mi experiencia con el Módulo Nativo y C++.

Dado que veremos muchas bibliotecas C/C++ escribiendo para las plataformas móviles, debemos implementarlas en nuestra aplicación iOS o React Native. Por eso quiero escribir un artículo sobre cómo exportar una función de C++ a React Native, que es fácil de entender y ahorra tiempo a los principiantes. Comenzaré con una nueva aplicación nativa de reacción.

1. Cree una nueva aplicación nativa de reacción, abra su terminal y ejecute

npx react-native init NativeModules

2. Abra Xcode y vaya a NativeModules/ios/NativeModule.xcworkspace

3. Trabajando en el lado de C++

Cree un nuevo archivo C++ y asígnele un nombreCpp_to_RN.cpp

Cuando creamos un nuevo archivo C++, Xcode creará un archivo de encabezado Cpp_to_RN.hpp para nosotros

Primero, abra el archivo " Cpp_to_RN.hpp" y cree una clase que incluya una función sin el cuerpo.

#ifndef Cpp_to_RN_hpp
#define Cpp_to_RN_hpp#include <stdio.h>
#include <string>class Cpp_to_RN {
public:
    std::string sayHello();
};#endif /* Cpp_to_RN_hpp */

Luego abre el Cpp_to_RN.cpparchivo y escribe una función simple “ sayHello()”

#include "Cpp_to_RN.hpp"
std::string Cpp_to_RN::sayHello(){
    return "Hello from CPP";
}

4. Trabajando en el archivo Wrapping C++.

Para envolver los archivos C++ y exportarlos al lado IOS (swift)

una. Cree un archivo Objective C y asígnele un nombreCpp_to_RN.m

Renombrar el Cpp_to_RN.m a Cpp_to_RN.mm

b. Abra el WrapCpp_to_RN.mm archivo y escriba el contenido del cuerpo que envolverá la función sayHellodel archivo C++.

#import <Foundation/Foundation.h>
#import "WrapCpp_to_RN.h"
#import "Cpp_to_RN.hpp"@implementation WrapCpp_to_RN- (NSString *) sayHello {
  Cpp_to_RN fromCPP;
    std::string helloWorldMessage = fromCPP.sayHello();
    return [NSString
            stringWithCString:helloWorldMessage.c_str()
            encoding:NSUTF8StringEncoding];
}
@end

C. Cree un archivo de encabezado y asígnele un nombreWrapCpp_to_RN.h

Exportar la wrapSayHellofunción al archivo Swift

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

5. Trabajando en el lado de iOS (Swift)

Para exportar la función C++ a React Native

una. Cree un archivo Swift y asígnele un nombreSendCpp_to_RN.swift

Nota: Xcode nos pedirá que creemos un NativeModules-Bridging-Header.harchivo para nosotros.

Crear una clase SendCpp_to_RNy declararla comoNSObject

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Escribir una función requiresMainQueueSetup()para evitar advertencias cuando ejecutamos la aplicación.

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Escriba una función para envolver el WrapCpp_to_RN()fromWrapCpp_to_RN.mm

import Foundation@objc(SendCpp_to_RN)
class SendCpp_to_RN : NSObject {
    
  @objc static func requiresMainQueueSetup() -> Bool {
        return false
    }
  
  @objc func fromCpp(_ successCallback: RCTResponseSenderBlock) -> Void {
    successCallback([NSNull(), WrapCpp_to_RN().wrapSayHello() as Any])
    }}

b. Exporte una función de ajuste en un archivo Swift a React Native

Cree un archivo Objective C para exportar la clase Swift y su función usandoCallback

#import <React/RCTBridgeModule.h>
#import <Foundation/Foundation.h>
#import "UIKit/UIKit.h"
@interface RCT_EXTERN_MODULE(SendCpp_to_RN, NSObject)RCT_EXTERN_METHOD(fromCpp:(RCTResponseSenderBlock)successCallback)@end

C. Conecte Swift a React Native, abra el NativeModules-Bridging-Header.h archivo

#import <React/RCTBridgeModule.h>#import <React/RCTViewManager.h>#import "WrapCpp_to_RN.h"

6. Trabajando en el lado de React Native

Llame a la clase Swift y sus funciones

import React from 'react';
import {StyleSheet, Text, View, NativeModules, Button} from 'react-native';const App = () => {
  const onPress = () => {
    const {SendCpp_to_RN} = NativeModules;
    SendCpp_to_RN.fromCpp((_err, res) => console.log(res));
  };
  return (
    <View style={styles.container}>
      <Text> Practice !</Text>
      <Button title="C++ to React Native" color="#841584" onPress={onPress} />
    </View>
  );
};
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});
export default App;

Y listo, solo ejecuta la aplicación

react-native run-ios

O simplemente haga clic en el botón "ejecutar" en Xcode y vea lo que hemos hecho.

Espero que mi artículo te sea útil, gracias por tu tiempo de lectura.

 Fuente: https://betterprogramming.pub/native-modules-export-c-function-to-react-native-for-beginners-77e89934b210

#cpp #cplusplus #react 

Cách Xuất Một Hàm Từ C ++ Sang React Native

Hôm nay, tôi tiếp tục chia sẻ kinh nghiệm của mình với Native Module và C ++.

Vì chúng ta sẽ thấy rất nhiều thư viện C / C ++ viết cho nền tảng di động, chúng ta cần triển khai chúng cho ứng dụng iOS hoặc React Native của mình. Đó là lý do mình muốn viết một bài hướng dẫn cách export một hàm từ C ++ sang React Native dễ hiểu và tiết kiệm thời gian cho người mới bắt đầu. Tôi sẽ bắt đầu với một ứng dụng gốc phản ứng mới

1. Tạo một ứng dụng gốc phản ứng mới, mở thiết bị đầu cuối của bạn và chạy

npx react-native init NativeModules

2. Mở Xcode và điều hướng đến NativeModules / ios / NativeModule.xcworkspace

3. Làm việc trên C ++

Tạo một tệp C ++ mới và đặt tên cho nóCpp_to_RN.cpp

Khi chúng tôi tạo tệp C ++ mới, Xcode sẽ tạo tệp tiêu đề Cpp_to_RN.hpp cho chúng tôi

Đầu tiên, mở tệp Cpp_to_RN.hpp“” và tạo một lớp bao gồm một hàm không có phần thân.

#ifndef Cpp_to_RN_hpp
#define Cpp_to_RN_hpp#include <stdio.h>
#include <string>class Cpp_to_RN {
public:
    std::string sayHello();
};#endif /* Cpp_to_RN_hpp */

Sau đó, mở Cpp_to_RN.cpptệp và viết một hàm đơn giản “ sayHello()”

#include "Cpp_to_RN.hpp"
std::string Cpp_to_RN::sayHello(){
    return "Hello from CPP";
}

4. Thao tác trên Wrapping C ++ file.

Để bọc các tệp C ++ và xuất chúng sang phía IOS (nhanh chóng)

một. Tạo một tệp Objective C và đặt tên cho nóCpp_to_RN.m

Đổi tên Cpp_to_RN.m thành Cpp_to_RN.mm

b. Mở WrapCpp_to_RN.mm tệp và viết nội dung phần nội dung sẽ bọc hàm sayHellotừ tệp C ++.

#import <Foundation/Foundation.h>
#import "WrapCpp_to_RN.h"
#import "Cpp_to_RN.hpp"@implementation WrapCpp_to_RN- (NSString *) sayHello {
  Cpp_to_RN fromCPP;
    std::string helloWorldMessage = fromCPP.sayHello();
    return [NSString
            stringWithCString:helloWorldMessage.c_str()
            encoding:NSUTF8StringEncoding];
}
@end

c. Tạo một tệp tiêu đề và đặt tên cho nóWrapCpp_to_RN.h

Xuất wrapSayHellohàm sang tệp Swift

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

5. Làm việc trên iOS (Swift)

Để xuất hàm C ++ sang React Native

một. Tạo một tệp Swift và đặt tên cho nóSendCpp_to_RN.swift

Lưu ý: Xcode sẽ yêu cầu chúng tôi tạo một NativeModules-Bridging-Header.htệp cho chúng tôi.

Tạo một lớp SendCpp_to_RNvà khai báo nó làNSObject

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Viết một hàm requiresMainQueueSetup()để ngăn cảnh báo khi chúng tôi chạy ứng dụng

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Viết một hàm để bọc WrapCpp_to_RN()từWrapCpp_to_RN.mm

import Foundation@objc(SendCpp_to_RN)
class SendCpp_to_RN : NSObject {
    
  @objc static func requiresMainQueueSetup() -> Bool {
        return false
    }
  
  @objc func fromCpp(_ successCallback: RCTResponseSenderBlock) -> Void {
    successCallback([NSNull(), WrapCpp_to_RN().wrapSayHello() as Any])
    }}

b. Xuất một hàm bọc trong tệp Swift sang React Native

Tạo một tệp Objective C để xuất lớp Swift và chức năng của nó bằng cách sử dụngCallback

#import <React/RCTBridgeModule.h>
#import <Foundation/Foundation.h>
#import "UIKit/UIKit.h"
@interface RCT_EXTERN_MODULE(SendCpp_to_RN, NSObject)RCT_EXTERN_METHOD(fromCpp:(RCTResponseSenderBlock)successCallback)@end

c. Kết nối Swift với React Native, mở NativeModules-Bridging-Header.h tệp

#import <React/RCTBridgeModule.h>#import <React/RCTViewManager.h>#import "WrapCpp_to_RN.h"

6. Làm việc ở phía React Native

Gọi lớp Swift và các chức năng của nó

import React from 'react';
import {StyleSheet, Text, View, NativeModules, Button} from 'react-native';const App = () => {
  const onPress = () => {
    const {SendCpp_to_RN} = NativeModules;
    SendCpp_to_RN.fromCpp((_err, res) => console.log(res));
  };
  return (
    <View style={styles.container}>
      <Text> Practice !</Text>
      <Button title="C++ to React Native" color="#841584" onPress={onPress} />
    </View>
  );
};
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});
export default App;

Và chúng tôi đã hoàn tất, chỉ cần chạy ứng dụng

react-native run-ios

Hoặc chỉ cần nhấp vào nút “chạy” trên Xcode và xem những gì chúng tôi đã làm.

Tôi hy vọng bài viết của tôi hữu ích cho bạn, cảm ơn bạn đã dành thời gian đọc.

 Nguồn: https://betterprogramming.pub/native-modules-export-c- Chức năng-to-react-native-for-beginners-77e89934b210

#cpp #cplusplus #react 

Como Exportar Uma Função De C++ Para React Native

Hoje, continuo compartilhando minha experiência com o Módulo Nativo e C++.

Como veremos muitas bibliotecas C/C++ escrevendo para plataformas móveis, precisamos implementá-las em nosso aplicativo iOS ou React Native. É por isso que quero escrever um artigo sobre como exportar uma função de C++ para React Native, que é fácil de entender e economiza tempo para iniciantes. Vou começar com um novo aplicativo nativo de reação

1. Crie um novo aplicativo nativo de reação, abra seu terminal e execute

npx react-native init NativeModules

2. Abra o Xcode e navegue até NativeModules/ios/NativeModule.xcworkspace

3. Trabalhando no lado C++

Crie um novo arquivo C++ e nomeie-oCpp_to_RN.cpp

Quando criamos um novo arquivo C++, o Xcode criará um arquivo de cabeçalho Cpp_to_RN.hpp para nós

Primeiro, abra o arquivo “ Cpp_to_RN.hpp” e crie uma classe que inclua uma função sem o corpo.

#ifndef Cpp_to_RN_hpp
#define Cpp_to_RN_hpp#include <stdio.h>
#include <string>class Cpp_to_RN {
public:
    std::string sayHello();
};#endif /* Cpp_to_RN_hpp */

Em seguida, abra o Cpp_to_RN.cpparquivo e escreva uma função simples “ sayHello()”

#include "Cpp_to_RN.hpp"
std::string Cpp_to_RN::sayHello(){
    return "Hello from CPP";
}

4. Trabalhando no arquivo C++ de encapsulamento.

Para encapsular os arquivos C++ e exportá-los para o lado IOS (swift)

uma. Crie um arquivo Objective C e nomeie-oCpp_to_RN.m

Renomeie o Cpp_to_RN.m para Cpp_to_RN.mm

b. Abra o WrapCpp_to_RN.mm arquivo e escreva o conteúdo do corpo que envolverá a função sayHellodo arquivo C++.

#import <Foundation/Foundation.h>
#import "WrapCpp_to_RN.h"
#import "Cpp_to_RN.hpp"@implementation WrapCpp_to_RN- (NSString *) sayHello {
  Cpp_to_RN fromCPP;
    std::string helloWorldMessage = fromCPP.sayHello();
    return [NSString
            stringWithCString:helloWorldMessage.c_str()
            encoding:NSUTF8StringEncoding];
}
@end

c. Crie um arquivo de cabeçalho e nomeie-oWrapCpp_to_RN.h

Exporte a wrapSayHellofunção para o arquivo Swift

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

5. Trabalhando no lado iOS (Swift)

Para exportar a função C++ para React Native

uma. Crie um arquivo Swift e nomeie-oSendCpp_to_RN.swift

Observação: o Xcode nos pedirá para criar um NativeModules-Bridging-Header.harquivo para nós.

Crie uma classe SendCpp_to_RNe declare-a comoNSObject

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Escreva uma função requiresMainQueueSetup()para evitar avisos quando executamos o aplicativo

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Escreva uma função para envolver o WrapCpp_to_RN()fromWrapCpp_to_RN.mm

import Foundation@objc(SendCpp_to_RN)
class SendCpp_to_RN : NSObject {
    
  @objc static func requiresMainQueueSetup() -> Bool {
        return false
    }
  
  @objc func fromCpp(_ successCallback: RCTResponseSenderBlock) -> Void {
    successCallback([NSNull(), WrapCpp_to_RN().wrapSayHello() as Any])
    }}

b. Exporte uma função wrap no arquivo Swift para React Native

Crie um arquivo Objective C para exportar a classe Swift e sua função usandoCallback

#import <React/RCTBridgeModule.h>
#import <Foundation/Foundation.h>
#import "UIKit/UIKit.h"
@interface RCT_EXTERN_MODULE(SendCpp_to_RN, NSObject)RCT_EXTERN_METHOD(fromCpp:(RCTResponseSenderBlock)successCallback)@end

c. Conecte o Swift ao React Native, abra o NativeModules-Bridging-Header.h arquivo

#import <React/RCTBridgeModule.h>#import <React/RCTViewManager.h>#import "WrapCpp_to_RN.h"

6. Trabalhando no lado React Native

Chame a classe Swift e suas funções

import React from 'react';
import {StyleSheet, Text, View, NativeModules, Button} from 'react-native';const App = () => {
  const onPress = () => {
    const {SendCpp_to_RN} = NativeModules;
    SendCpp_to_RN.fromCpp((_err, res) => console.log(res));
  };
  return (
    <View style={styles.container}>
      <Text> Practice !</Text>
      <Button title="C++ to React Native" color="#841584" onPress={onPress} />
    </View>
  );
};
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});
export default App;

E pronto, basta executar o aplicativo

react-native run-ios

Ou apenas clique no botão “executar” no Xcode e veja o que fizemos.

Espero que meu artigo seja útil para você, obrigado pelo tempo de leitura.

 Fonte: https://betterprogramming.pub/native-modules-export-c-function-to-react-native-for-beginners-77e89934b210

#cpp #cplusplus #react