How to send data from MainActivity to React Native side

[BraveEvidence]

I have enabled the new architecture for android using React Native v0.74. I need to pass some data from MainActivity to React Native. Previously I used to use something like below code

val context = this.reactNativeHost.reactInstanceManager.currentReactContext
context!!.getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter::class.java)?.emit("result", "data:image/png;base64," + Base64.encodeToString(byteArray, Base64.DEFAULT))

But I get a crash saying context is null, this way used to work with React Native 0.73 for new and old arch, what is the recommended approach now

[cortinico]

what is the recommended approach now

You would have to use the EventDispatcher.
Example on how to use it is here: react-native-menu/menu#749

[Bardiamist]

@cortinico Hey, example is difficult, do we have simple example for MainActivity? Would be good to have it in the documentation.

[BraveEvidence]

@cortinico Thanks for the reply. The example you mentioned is of Fabric Components. Is the approach same for sending string data from MainActivity if I don't have a Fabric Component.

Also, I did try the approach yo recommended

class SendDataEvent(
    surfaceId: Int,
    viewTag: Int,
    private val event: String?,
    private val target: Int
) : Event<SendDataEvent>(surfaceId, viewTag) {

    override fun getEventName(): String = "onPressAction"
    override fun getEventData(): WritableMap = Arguments.createMap().apply {
        if (event != null) {
            putString("event", event)
        }
        putString("target", target.toString())
    }
}


 val id = 1
                val dispatcher =
                    UIManagerHelper.getEventDispatcherForReactTag(context,id)
                dispatcher?.dispatchEvent(SendDataEvent(UIManagerHelper.getSurfaceId(this), id, "data:image/png;base64," + Base64.encodeToString(byteArray, Base64.DEFAULT), id))

Yo can please guide on how do I listen to this in my react component

[lovegaoshi]

I dont think fabric or not matters..?
migration from RCTEventEmitter to dispatchEvent:
https://github.com/lovegaoshi/react-native-svga-player/pull/3/files#diff-9385651304063e779a30875dff3f371ee25644eb3430e8658e900acf11c787e8R28

event listener in js:
https://github.com/lovegaoshi/react-native-svga-player/blob/588c9a2819cb2fe14dd7204addaeadd4bf049333/index.js#L56

not that I really know if any of this is right, but my lib seems working still

[BraveEvidence]

@lovegaoshi Thanks for the reply, can you tell how to get the react context in MainActivity. I am using below code

val context = this.reactNativeHost.reactInstanceManager.currentReactContext

but the context always is null. Any other way to get the context in MainActivity

[lovegaoshi]

i dont think this has to do with the new arch, bjut if u wanna try by all means please do
https://github.com/lovegaoshi/azusa-player-mobile/blob/3c8d25e4b3a19d541fe7be45b10b2fa1e38b349d/android/app/src/main/java/com/noxplay/noxplayer/MainActivity.kt#L87

[BraveEvidence]

@lovegaoshi The code is the same which I am using , I get the context null.

[fgrs]

I'm facing same issue, has anybody figured out? What's the proper (new architecture) way?