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I'm trying to bridge my React-Native 0.33 code to a super simple Swift method, following this guide but all I'm getting is show:(NSString *)name is not a recognized Objective-C method.

Here's my code:

SwitchManager.swift

import Foundation

@objc(SwitchManager)
class SwitchManager: NSObject {

  @objc func show(name: String) -> Void {
    NSLog("%@", name);
  }

}

SwitchManagerBridge.h

#import "RCTBridgeModule.h"

@interface RCT_EXTERN_MODULE(SwitchManager, NSObject)

RCT_EXTERN_METHOD(show:(NSString *)name)

@end

SwitchManager-Bridging-Header.h

#import "RCTBridgeModule.h"

Then on my index.ios.js file I'm importing SwitchManager with import { SwitchManager } from 'NativeModules'; and calling SwitchManager.show('One');. This is where the error happened.

Not sure what's wrong.

Answers

This is a part of Swift 3's changes and can be solved by adding an underscore:

import Foundation

@objc(SwitchManager)
class SwitchManager: NSObject {

  @objc func show(_ name: String) {
    NSLog("%@", name);
  }

}

See Swift 3's 0046 Proposal: Establish consistent label behavior across all parameters including first labels that is called out in the Swift.org migration guide under "Consistent first argument labels".

Basically, how Objective-C sees Swift methods has changed with Swift 3.

EDIT: This is still the case in Swift 4, see docs here under Omitting Argument Labels.