See swift stdout for a react-native application

Question

Say I have the following React Native code:

import { NativeModules, Platform } from 'react-native'

if (Platform.OS === 'ios') {
  NativeModules.ExampleThing.exampleMethod('example')
}

The following Swift class:

@objc(ExampleThing)
class ExampleThing: NSObject {
  private override init() {
    print('init')
  }

  @objc func exampleMethod(_ message: String) -> Void {
    print(message)
    //do more complex thing
  }
}

and the following bridging header:

#import <Foundation/Foundation.h>
#import <React/RCTBridgeModule.h>

@interface RCT_EXTERN_MODULE(ExampleThing, NSObject)

RCT_EXTERN_METHOD(exampleMethod:(NSString *)message)
@end

When I run react-native run-ios , the app starts in the simulator just fine, eg: the effect of exampleMethod (send a message to Segment.IO) occurs, ergo exampleMethod is quite clearly getting called correctly. However, for the life of me, I can not find where the print command is printing to. I've also tried os_log

Answer 1

You'd need to run the project through XCode instead of react-native run-ios , and it'll be shown on the XCode output console.

You can also make use of XCode's breakpoints etc instead of print statements to help in debugging.