I’m working on a Flutter plugin that shows a few native screens but as the documentation for https://docs.flutter.dev/platform-integration/ios/platform-views nor https://docs.flutter.dev/platform-integration/android/platform-views offers a specific approach for this case I’m not sure if I should register in the Plugin multiple FlutterPlatformViewFactory and FlutterPlatformView each one point to a specific native view, or is it safe to register only one pair and dynamically attach the native screen view i need to the FlutterPlatformView by passing a value in the view params from Flutter and picking the screen I need using an enum and as I implemented here:

native screen selector enum

import Foundation
import Flutter

enum ViewControllerGetter: String {
    case viewController
    case viewController2

    func getViewController (with params: [String: AnyObject]?) -> UIViewController? {
        switch self {
        case .viewController:
            if params != nil {
                var vc : UIViewController = UIViewController()
                // first we get the binaryMessenger from params as it has been added to them in FlutterPlatformView
                if let binaryMessenger = params!["binaryMessenger"] as? FlutterBinaryMessenger {
                    
                    print("ViewControllerGetter binaryMessenger (binaryMessenger.description)");
                    // then we initialize the ViewController with it, to create a FLutterMethodChannel which needs a binaryMessenger
                    // than normally we take from AppDelegate rootViewController, but as theis is a Plug-in we don't have any AppDelegate
                    let vcToShow = ViewController(withParameter: binaryMessenger, methodChannelId: params!["methodChannelId"] as! String);
                    
                    // then we set other ViwController variables and values
                    if let param1 = params!["param 1"] {
                        vcToShow.buttonTitleA = param1 as? String
                    }
                    if let param2 = params!["param 2"] {
                        vcToShow.buttonTitleB = param2 as? String
                    }
                    // then we overwrite the Empty ViewController to be returned with the instantiated ViewController
                    vc = vcToShow
                }
                
                // we can finally return the ViewController to be attached to the FlutterPlatformView UIView
                return vc
            }
        case .viewController2:
            if params != nil {
                var vc : UIViewController = UIViewController()
                // first we get the binaryMessenger from params as it has been added to them in FlutterPlatformView
                if let binaryMessenger = params!["binaryMessenger"] as? FlutterBinaryMessenger {
                    
                    print("ViewControllerGetter binaryMessenger (binaryMessenger.description)");
                    // then we initialize the ViewController with it, to create a FlutterMethodChannel which needs a binaryMessenger
                    // than normally we take from AppDelegate rootViewController, but as this is a Plug-in we don't have any AppDelegate
                    let vcToShow = ViewController2(withParameter: binaryMessenger, methodChannelId: params!["methodChannelId"] as! String);
                    
                    // then we set other ViewController variables and values
                    if let param1 = params!["param 1"] {
                        vcToShow.buttonTitleA = param1 as? String
                    }
                    if let param2 = params!["param 2"] {
                        vcToShow.buttonTitleB = param2 as? String
                    }
                    
                    if let param3 = params!["param 3"] {
                        vcToShow.buttonTitleC = param3 as? String
                    }
                    // then we overwrite the Empty ViewController to be returned with the instantiated ViewController
                    vc = vcToShow
                }
                
                // we can finally return the ViewController to be attached to the FlutterPlatformView UIVIew
                return vc
            }

        }
        return nil
    }
}

FlutterPlatformViewFactory – FlutterPlatformView

import Flutter
import UIKit


class DynamicNativeViewFactory: NSObject, FlutterPlatformViewFactory {
    private var messenger: FlutterBinaryMessenger
    init(messenger: FlutterBinaryMessenger) {
        self.messenger = messenger
        super.init()
    }

    func create(
        withFrame frame: CGRect,
        viewIdentifier viewId: Int64,
        arguments args: Any?
    ) -> FlutterPlatformView {
        return DynamicNativeView(
            frame: frame,
            viewIdentifier: viewId,
            arguments: args,
            binaryMessenger: messenger)
    }

    public func createArgsCodec() -> FlutterMessageCodec & NSObjectProtocol {
          return FlutterStandardMessageCodec.sharedInstance()
    }
}

class DynamicNativeView: NSObject, FlutterPlatformView {
    private var vc: UIViewController = UIViewController();
    

    init(
        frame: CGRect,
        viewIdentifier viewId: Int64,
        arguments args: Any?,
        binaryMessenger messenger: FlutterBinaryMessenger?
    ) {
        if var params = args as? [String:AnyObject] {
            print("DynamicNativeView binaryMessenger (messenger?.description)");
            let screen: String = params["screen"] as! String;
            // we add the binary messenger
            params["binaryMessenger"] = messenger;
            
            if let vcToShow = ViewControllerGetter(rawValue: screen)?.getViewController(with: params) {

            vc = vcToShow
                // _view = vcToShow.view /// breaks touch
            }
        }
        super.init()
        // _view.addSubview(vc.view)
    }

    func view() -> UIView {
        // _view.addSubview(vc.view)
        // return _view
        return vc.view
    }
}

FlutterPlugin

import Flutter
import UIKit

public class NativePlugin: NSObject, FlutterPlugin {
  public static func register(with registrar: FlutterPluginRegistrar) {
    let channel = FlutterMethodChannel(name: "native_plugin", binaryMessenger: registrar.messenger())

    
    let instance = NativePlugin()
    registrar.addMethodCallDelegate(instance, channel: channel)

    let viewFactory = DynamicNativeViewFactory(messenger: registrar.messenger())
    registrar.register(
      viewFactory,
          withId: "native_screen"
          )
  }

  public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
    switch call.method {
    case "getPlatformVersion":
      result("iOS " + UIDevice.current.systemVersion)
    default:
      result(FlutterMethodNotImplemented)
    }
  }
}

Flutter plugin’s PlatformView Widget

class NativeViewer extends StatefulWidget {
  final Map<String, dynamic> viewParams;
  const NativeViewer({
    super.key,
    required this.viewParams,
  });

  @override
  State<NativeViewer> createState() => _NativeViewerState();
}

class _NativeViewerState extends State<NativeViewer> {
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    const String viewType = 'native_screen';
    final Map<String, dynamic> creationParams = widget.viewParams;

    return AdatptivePlatformView(
      viewType: viewType,
      layoutDirection: TextDirection.ltr,
      creationParams: creationParams,
      creationParamsCodec: const StandardMessageCodec(),
    );
  }
}

class AdatptivePlatformView extends StatelessWidget {
  final String viewType;
  final dynamic creationParams;
  final TextDirection? layoutDirection;
  final MessageCodec<dynamic>? creationParamsCodec;
  const AdatptivePlatformView({
    super.key,
    required this.viewType,
    this.creationParams,
    this.creationParamsCodec,
    this.layoutDirection,
  });

  @override
  Widget build(BuildContext context) {
    return Platform.isAndroid
        ? AndroidView(
            viewType: viewType,
            layoutDirection: TextDirection.ltr,
            creationParams: creationParams,
            creationParamsCodec: const StandardMessageCodec(),
          )
        : UiKitView(
            viewType: viewType,
            layoutDirection: TextDirection.ltr,
            creationParams: creationParams,
            creationParamsCodec: const StandardMessageCodec(),
            gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{
              Factory<OneSequenceGestureRecognizer>(
                () => EagerGestureRecognizer(),
              ),
            },
          );
  }
}

Both approaches work but I don’t seem to be able to find info about best practices or bad practices for this case.

My concern is that while registering only one FlutterPlatformViewFactory with the plugin would make sure that there is no id problem because it’s only one, this could lead to issues like memory leaks for instance when I use the plugin widget in different Flutter screens so the plugin would register it again with the same id.
I don’t find in the docs any reference about its de-registration, so I don’t know if this is a safe approach as perhaps the FlutterPlatformViewFactory gets deregistered when closing the Flutter screen that uses the plugin widget freeing up resources taken as it happens when a new FlutterMethodChannelHandler gets registered on the same channel de-registering any previously registered one or it stays registered anyways.

Can you point me to some part of the docs I missed or to any article or some Flutter plugin that does have multiple native screens for its UI?
As always your help is very much appreciated