Example of calling swift code from RN

App.tsx

@@ -1,12 +1,13 @@
 import { NewAppScreen } from '@react-native/new-app-screen'
 import { useEffect, useState } from 'react'
-import { StatusBar, Text, StyleSheet, useColorScheme, ScrollView } from 'react-native'
+import { StatusBar, Text, StyleSheet, useColorScheme, ScrollView, Button, Alert } from 'react-native'
 import { NativeEventEmitter, NativeModules } from 'react-native'
 
-const { Emitter } = NativeModules
+const { Emitter, TestingServiceModule } = NativeModules
 
 import { requireNativeComponent } from 'react-native'
 import type { StyleProp, ViewStyle } from 'react-native'
+
 type CustomButtonProps = {
   style?: StyleProp<ViewStyle>
 }
@@ -15,9 +16,23 @@ const BaseButton = requireNativeComponent<CustomButtonProps>('BaseButton')
 
 export default function App() {
   const isDarkMode = useColorScheme() === 'dark'
-  const [message, setMessage] = useState(null)
+  const [message, setMessage] = useState<string|null>(null)
   const [color, setColor] = useState("#FFF")
   
+
+  const onPress = async () => {
+    if (!TestingServiceModule?.greet) {
+      Alert.alert('Module not found', 'MyNativeModule is not linked or not exported.')
+      return
+    }
+    try {
+      const result = await TestingServiceModule.greet('John')
+      setMessage(result);
+    } catch (e) {
+      //Alert.alert('Error', String(e?.message ?? e))
+    }
+  }
+
   useEffect(() => {
     const emitter = new NativeEventEmitter(Emitter);
     const subscription = emitter.addListener('onMessage', (event) => {
@@ -28,6 +43,14 @@ export default function App() {
           setColor("#00F")
         }
       }
+
+      TestingServiceModule.greet('John')
+        .then((message: string) => {
+          setMessage(message)
+        })
+        .catch((error: string) => {
+          console.error(error);
+        });
     })
 
     return () => {
@@ -41,6 +64,7 @@ export default function App() {
       <Text>{message ?? 'Waiting for message...'}</Text>
       <CustomButton style={{ height: 200 }} />
       <BaseButton style={{ height: 200 }} />
+      <Button title="Call Swift greet()" onPress={onPress} />
     </ScrollView>
   );
 }

ios/Native/Application/RNPlayground-Bridging-Header.h

@@ -1,2 +1,3 @@
 
 #import <React/RCTViewManager.h>
+#import <React/RCTBridgeModule.h>

ios/Native/Application/Services/TestingService.swift

@@ -0,0 +1,31 @@
+//
+//  TestingService.swift
+//  RNPlayground
+//
+//  Created by Artur Gurgul on 03/08/2025.
+//
+
+import Foundation
+import React
+
+@objc(TestingServiceModule)
+class TestingServiceModule: NSObject {
+
+  @objc
+  func greet(_ name: String,
+             resolver resolve: @escaping RCTPromiseResolveBlock,
+             rejecter reject: @escaping RCTPromiseRejectBlock) {
+    let message = "Hello, \(name)! From Swift."
+    resolve(message)
+  }
+
+  @objc
+  func constantsToExport() -> [AnyHashable: Any]! {
+    return ["greeting": "Hello from Swift"]
+  }
+
+  @objc
+  static func requiresMainQueueSetup() -> Bool {
+    return false
+  }
+}

ios/Native/Application/Services/TestingServiceModuleBridge.m

@@ -0,0 +1,17 @@
+//
+//  TestingServiceModuleBridge.m
+//  RNPlayground
+//
+//  Created by Artur Gurgul on 03/08/2025.
+//
+
+#import <React/RCTBridgeModule.h>
+
+// This tells React Native about the Swift class
+@interface RCT_EXTERN_MODULE(TestingServiceModule, NSObject)
+
+RCT_EXTERN_METHOD(greet:(NSString *)name
+                  resolver:(RCTPromiseResolveBlock)resolve
+                  rejecter:(RCTPromiseRejectBlock)reject)
+
+@end

ios/Native/Application/Shared/SharedState.swift

@@ -16,7 +16,7 @@ final class SharedState: ObservableObject {
   private let emitter = EventEmitter.sharedInstance
   
   // SwiftUI => RN => SwiftUI
-  @Published var text1: String = ""
+  @Published var message: String = ""
   
   func send(message: String) {
     emitter.send(message: message)

ios/Native/Application/Views/BaseButton/BaseButton.swift

@@ -12,7 +12,7 @@ struct BaseButton: View {
   
   var body: some View {
     Button("SwiftUI Button") {
-      sharedState.text1 = "Clicked in SwiftUI button that was created in RN"
+      sharedState.message = "Clicked in SwiftUI button that was created in RN"
     }
   }
 }

ios/Native/Application/Views/CustomButton/CustomButtonManager.m

@@ -1,3 +1,10 @@
+//
+//  CustomButtonManager.m
+//  RNPlayground
+//
+//  Created by Artur Gurgul on 02/08/2025.
+//
+
 #import <React/RCTViewManager.h>
 
 @interface RCT_EXTERN_MODULE(CustomButtonManager, RCTViewManager)

ios/Native/Application/Views/ToolboxHeader.swift

@@ -18,7 +18,7 @@ struct ToolboxHeader: View {
           sharedState.send(message: "hello from Swift!")
         }
       }
-      Text("SwiftUI => RN => SwiftUI: \(sharedState.text1)")
+      Text("Message: \(sharedState.message)")
     }
   }
 }