Integrating Mobile SDK in existing React Native app

Sorry for the late answer , I believe the below step might help you. you can manually add the Salesforce SDK to your project create a new folder called mobileSDK and add in the iOS [sdk][1] and Android [SDK][2] from salesforce

preferred way is just add a new file for each ios and android

For android create a new file in project root call it "installandroid.js" then paste the below code and save it

#!/usr/bin/env node

var packageJson = require('./package.json')
var execSync = require('child_process').execSync;
var path = require('path');
var fs = require('fs');

console.log('Installing npm dependencies');
execSync('yarn install', {stdio:[0,1,2]});

var rimraf = require('rimraf');

console.log('Installing sdk dependencies');
var sdkDependency = 'SalesforceMobileSDK-Android';
var repoUrlWithBranch = packageJson.sdkDependencies[sdkDependency];
var parts = repoUrlWithBranch.split('#'), repoUrl = parts[0], branch = parts.length > 1 ? parts[1] : 'master';
var targetDir = path.join('mobile_sdk', sdkDependency);
if (fs.existsSync(targetDir)) {
    console.log(targetDir + ' already exists - if you want to refresh it, please remove it and re-run install.js');
} else {
execSync('git clone --branch ' + branch + ' --single-branch --depth 1 ' + repoUrl + ' ' + targetDir, {stdio:[0,1,2]});
    rimraf.sync(path.join('mobile_sdk', 'SalesforceMobileSDK-Android', 'hybrid'));
    rimraf.sync(path.join('mobile_sdk', 'SalesforceMobileSDK-Android', 'libs', 'test'));
    rimraf.sync(path.join('mobile_sdk', 'SalesforceMobileSDK-Android', 'libs', 'SalesforceReact', 'package.json')); // confuses metro bundler
}

similarly create a file called "installios.js" in the root of the project and paste the below code and save it

#!/usr/bin/env node

var packageJson = require('./package.json')
var execSync = require('child_process').execSync;
var path = require('path');
var fs = require('fs');

console.log('Installing npm dependencies');
execSync('yarn install', {stdio:[0,1,2]});

console.log('Installing sdk dependencies');
var sdkDependency = 'SalesforceMobileSDK-iOS';
var repoUrlWithBranch = packageJson.sdkDependencies[sdkDependency];
var parts = repoUrlWithBranch.split('#'), repoUrl = parts[0], branch = parts.length > 1 ? parts[1] : 'master';
var targetDir = path.join('mobile_sdk', sdkDependency);
if (fs.existsSync(targetDir)) {
    console.log(targetDir + ' already exists - if you want to refresh it, please remove it and re-run install.js');
} else {
    execSync('git clone --branch ' + branch + ' --single-branch --depth 1 ' + repoUrl + ' ' + targetDir, {stdio:[0,1,2]});
}

console.log('Installing pod dependencies');
execSync('pod update', {stdio:[0,1,2], cwd:'ios'});

Then go to terminal or command prompt , point to your project root folder then execute the below commands

node ./installios.js

Once its completed then run

node ./installandroid.js

Hope this helps to make the salesforce integrated in your app.

But unfortunately I am unable to help you up with code changes in the code level [1]: https://github.com/forcedotcom/SalesforceMobileSDK-iOS [2]: https://github.com/forcedotcom/SalesforceMobileSDK-Android

If you are using CocoaPods this can be easily done for IOS as below.

You will need to install the Cocoapod first

brew install cocoapods

Create a default pod file if you do not have one

pod init

Make sure you have pod file as here

Now run the below command to get all dependencies

pod install

If this fails with errors mentioning xcrun, make sure that in Xcode in Preferences > Locations the Command Line Tools are assigned.