Qt IOS Application Extension - Packet Tunnel for Custom VPN Functionality

I am trying to create an application extension which provides vpn functionality over network extension with packet-tunnel. But when I enable vpn it doesn't call related callbacks.

Currently, i didn't find any example in qt documentation. So I read the documents of ios and qt and trying to find the right path.

Here is the CMakeLists.txt

add_executable(overlay-service MACOSX_BUNDLE main.cpp tunnel_provider.h tunnel_provider.mm)
   
   set_target_properties(overlay-service PROPERTIES
       MACOSX_BUNDLE_IDENTIFIER org.zenarmor.zenoverlay.network-extension
       BUNDLE YES
       XCODE_PRODUCT_TYPE com.apple.product-type.app-extension
       # XCODE_EMBED_FRAMEWORKS /System/Library/Frameworks/NetworkExtension.framework
   )

target_link_libraries(
   overlay-service

   PUBLIC
       Qt6::CorePrivate
       overlay-lib
)

tunnel_provider.h

#ifndef _TUNNEL_PROVIDER_H
#define _TUNNEL_PROVIDER_H

#import <Foundation/Foundation.h>
#import <NetworkExtension/NetworkExtension.h>

@interface ZenTunnelProvider : NEPacketTunnelProvider {
    int fd;
}

- (void) startTunnelWithOptions:(NSDictionary<NSString *,NSObject *> *) options
              completionHandler:(void (^)(NSError * error)) completionHandler;
- (void) stopTunnelWithReason:(NEProviderStopReason) reason
            completionHandler:(void (^)()) completionHandler;
@end

#endif

tunnel_provider.mm

#import <Foundation/Foundation.h>
#import <os/log.h>

@implementation ZenTunnelProvider
- (void) startTunnelWithOptions:(NSDictionary<NSString *,NSObject *> *) options
              completionHandler:(void (^)(NSError * error)) completionHandler {

    NSLog(@"===================== Tunnel Started, x=%i, %@", 5, self.protocolConfiguration);

    completionHandler(nil);
}
- (void) stopTunnelWithReason:(NEProviderStopReason) reason
            completionHandler:(void (^)()) completionHandler{
    NSLog(@"===================== Tunnel Stopped");;
    completionHandler();
}

@end

How I create configuration is:

        provider_protocol.providerBundleIdentifier = @"org.zenarmor.zenoverlay.packet-tunnel";
        provider_protocol.serverAddress = @"0.0.0.0";
        provider_protocol.providerConfiguration = @{
            @"helloString" : @"Hello, World!",
            @"magicNumber" : @42
        };

      NSLog(@"===================== Vpn configuration is written, x=%i", 5);

        vpn_manager.protocolConfiguration = provider_protocol;
        vpn_manager.localizedDescription  = @"ZenOverlayTunnel";
        vpn_manager.enabled               = true;

        [vpn_manager saveToPreferencesWithCompletionHandler:^(NSError * _Nullable error) {
            if (error)
            {
                NSLog(@"err: %@", error);
            }
            else
            {
                NSLog(@"Successfully saved");
            }
        }];

main.cpp

#include <QCoreApplication>
#include <iostream>

int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);
    std::cout << "Hello world" << std::endl;
    return app.exec();
}

startTunnelWithOptions is not triggered when I enable vpn from settings on IOS. Could anyone. help to identify the issue?