How to stream data from swift to flutter using event channel?

Question

I am making an app in which I stream data from native android and iOS side to flutter side and there I display the data in the UI.

I already did the android part. The android part is sending the data to flutter side and displays them in UI. But the problem is how to achieve same for iOS swift side.

Android code that works for me:

new EventChannel(getFlutterView(), "Eventchannelname").setStreamHandler(
            new EventChannel.StreamHandler() {
                @Override
                public void onListen(Object args, EventChannel.EventSink events) {
                    Log.w(TAG, "adding listener");
                    mEventSink = events; // I use mEventsink.success(data) to pass the data to flutter side

                @Override
                public void onCancel(Object args) {
                    Log.w(TAG, "cancelling listener");
                }
            }
    );

How can I achieve the same in Swift native code. I googled it and did not find anything that can help me.

I want same in swift as what I did in android java: I want to capture the events in local variable and then use that where I need to send data to flutter.

Solution

just call mEventSink as a function

mEventSink(data)

Use FlutterEndOfEventStream constant to signal end of stream

mEventSink(FlutterEndOfEventStream)

if you going to send error to flutter side use

mEventSink(FlutterError(code: "ERROR_CODE",
                             message: "Detailed message",
                             details: nil))

Reference to API DOC

Complete swift example

let eventChannel = FlutterEventChannel(name: "your.channel.id", binaryMessenger: messenger!)                                                                            
        eventChannel.setStreamHandler(SwiftStreamHandler())      

.... 

class SwiftStreamHandler: NSObject, FlutterStreamHandler {                                                                                                                                  
    public func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink) -> FlutterError? {                                                                     
        events(true) // any generic type or more compex dictionary of [String:Any]
        events(FlutterError(code: "ERROR_CODE",
                             message: "Detailed message",
                             details: nil)) // in case of errors
        events(FlutterEndOfEventStream) // when stream is over
        return nil                                                                                                                                                                           
    }                                                                                                                                                                                        

    public func onCancel(withArguments arguments: Any?) -> FlutterError? {                                                                                                                   
        return nil                                                                                                                                                                           
    }                                                                                                                                                                                        
}               

Comments

[Zakria Khan]

I know on java side I want to same same thing in swift language.

[Alexei Volkov]

My answer is about swift code check the api reference i mentioned.

[User]

Can you add the declaration/instantiation of messenger?

[Sadeny Alpha]

is thee anyone who has it working? am stuck the stream handler seem not to send the data