receive event from flutter

Commands.swift

class Commands : NSObject {
    let COMMANDS = "/COMMANDS";
    let CMD_OPEN_DIALOG = "CMD:OPEN_DIALOG";
    
    weak var binaryMessager : FlutterBinaryMessenger?
    var methodChannel : FlutterMethodChannel?
    
    func methodInvoked(call: FlutterMethodCall, result: @escaping FlutterResult) -> Void {
        NSLog(call.method);
        switch(call.method) {
        case self.CMD_OPEN_DIALOG:
            let dict = call.arguments as! Dictionary<String, String>;
            let dialog = OpenDialog()
            dialog.openFileDialog(
                title: dict["title"] ?? "Import Files",
                fileTypes: dict["types"] ?? "*",
                result: result);
            break;
        default:
            result(FlutterMethodNotImplemented);
        }
    }
    
    func register(withBinaryMessager bm: FlutterBinaryMessenger) {
        // save binary messager
        binaryMessager = bm;

        // create a method channel
        let channelName = (Bundle.main.infoDictionary?["CFBundleIdentifier"] as! String) + COMMANDS
        methodChannel = FlutterMethodChannel.init(name: channelName, binaryMessenger: binaryMessager!)
        methodChannel?.setMethodCallHandler(self.methodInvoked(call:result:));
    }
}