Create a React Native custom module (with Swift)

Here is a quick and dirty example of how one can expose a custom module to React Native using Swift.

Product-Bridging-Header.h – Bridge header file

#import "RCTBridgeModule.h"

MySwiftThingy.m – Register Swift code with the React Native Bridge

#import "RCTBridgeModule.h"

@interface RCT_EXTERN_MODULE(MySwiftThingy, NSObject)

RCT_EXTERN_METHOD(callbackMethod:(RCTResponseSenderBlock)callback)
RCT_EXTERN_METHOD(simpleMethod:(NSString *)message)

@end

MySwiftThingy.swift – Custom Swift component

import Foundation

@objc(MySwiftThingy)
class MySwiftThingy: NSObject {
  
  @objc func callbackMethod(callback: RCTResponseSenderBlock) -> Void {
    let resultsDict = [
      "success" : true
    ];
    
    callback([NSNull() ,resultsDict])
  }
  
  @objc func simpleMethod(message: String!) {
    print("\(message)")
  }
}

Call it from JavaScript:

      const { MySwiftThingy } = require('NativeModules');
      MySwiftThingy.simpleMethod('hi');
      MySwiftThingy.callbackMethod((err,r) => console.log(r));