Pass Optional JSON to Swift from react-native

Question

Say I have the following Swift class:

@objc(ExampleClass)
  class ExampleClass: NSObject {
  init() {}
  @objc func exampleMethod(_ message: String, _ properties: [String: Any]? = nil) -> Void {}
}

And the following Header:

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

@interface RCT_EXTERN_MODULE(ExampleClass, NSObject)

RCT_EXTERN_METHOD(exampleMethod:(NSString *)name (NSDictionary *)properties)
@end

Which I then call with the following React Native code:

import { NativeModules } from 'react-native'

NativeModules.ExampleClass.exampleMethod('example', {'hello': 'world'})

This results in the following error message:

ExceptionsManager.js:73 Exception 'exampleMethod: is not a recognized Objective-C method.' was thrown while invoking trackEvent on target SegmentTracker with params (
    "example",
        {
        hello = world;
    }
)

While calling it like so:

NativeModules.ExampleClass.exampleMethod('example')

results in:

ExceptionsManager.js:73 Exception 'exampleMethod: is not a recognized Objective-C method.' was thrown while invoking trackEvent on target SegmentTracker with params (
    "example"
)

I have two questions: 1) How do I pass JSON from React Native to Swift? 2) How do I correctly allow for optional parameters in RCT_EXTERN_METHOD? And if that's not possible, how do I handle the case where I would like to sometimes pass a second parameter, and sometimes not?

score 0 · Answer 1 · edited Jul 23 '19 at 05:13

0

You could try with properties of type NSDictionary so that it fits to the interface. It could be similar to:

react-native-bridging-passing-json-to-swift-function

edited Jul 23 '19 at 05:13

Jeff

840
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29

answered Dec 13 '18 at 19:14

Jan F.

1,681
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27

score 0 · Answer 2 · answered May 25 '21 at 17:02

0

You need to use a static method in the swift code @objc static func exampleMethod(...

answered May 25 '21 at 17:02

dondragon2

535
5
15

score 0 · Answer 3 · answered Jun 02 '21 at 20:19

your swift code should be

@objc(ExampleClass)
class ExampleClass: NSObject {
  @objc(exampleMethod:properties:) func exampleMethod(_ message: String, properties: [String: Any]? = nil) -> Void {}
}

And your bridge file should be

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

@interface RCT_EXTERN_MODULE(ExampleClass, NSObject)

RCT_EXTERN_METHOD(exampleMethod:(NSString *)name properties:(NSDictionary *)properties)
@end

Pass Optional JSON to Swift from react-native

3 Answers3