Creating Notification Service Extension

The Notification Service Extension modifies the notification content by adding actions, push polls and allows you to take advantage of iOS 10+ notification features.

1. Add new target to your project (File->New->Target) and create Notification Service Extension, and name it PushbotsNSExtension , Press cancel on the "Activate PushbotsNSExtension  scheme" prompt:

Make sure deployment info > Target of the Notification Extension Service is set to 10 or higher under General tab.

2. Open NotificationService.m  or  NotificationService.swift  under PushbotsNSExtension Group 

and copy the code below:
Objective-C  NotificationService.m 

//  NotificationService.m
#import <Pushbots/Pushbots.h>
#import "NotificationService.h"

@interface NotificationService ()

@property (nonatomic, strong) void (^contentHandler)(UNNotificationContent *contentToDeliver);
@property (nonatomic, strong) UNMutableNotificationContent *bestAttemptContent;
@property (nonatomic, strong) UNNotificationRequest *notificationRequest;

@end

@implementation NotificationService

- (void)didReceiveNotificationRequest:(UNNotificationRequest *)request withContentHandler:(void (^)(UNNotificationContent * _Nonnull))contentHandler {
    self.notificationRequest = request;
    self.contentHandler = contentHandler;
    self.bestAttemptContent = [request.content mutableCopy];

    [Pushbots didReceiveNotificationExtensionRequest:self.notificationRequest withContent:self.bestAttemptContent];
    self.contentHandler(self.bestAttemptContent);
}

- (void)serviceExtensionTimeWillExpire {
    // Called just before the extension will be terminated by the system.
    // Use this as an opportunity to deliver your "best attempt" at modified content, otherwise the original push payload will be used.
    [Pushbots serviceExtensionTimeWillExpireRequest:self.notificationRequest withContent:self.bestAttemptContent];
    self.contentHandler(self.bestAttemptContent);
}

@end

Swift  NotificationService.swift 

//  NotificationService.swift

import UserNotifications
import Pushbots

class NotificationService: UNNotificationServiceExtension {

    var contentHandler: ((UNNotificationContent) -> Void)?
    var bestAttemptContent: UNMutableNotificationContent?
    var notificationRequest: UNNotificationRequest!
    
    override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
        self.contentHandler = contentHandler
        self.notificationRequest = request;
        bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)
        
        if let bestAttemptContent = bestAttemptContent {
            Pushbots.didReceiveNotificationExtensionRequest(self.notificationRequest, with: self.bestAttemptContent)
            contentHandler(bestAttemptContent)
        }
    }
    
    override func serviceExtensionTimeWillExpire() {
        // Called just before the extension will be terminated by the system.
        // Use this as an opportunity to deliver your "best attempt" at modified content, otherwise the original push payload will be used.
        if let contentHandler = contentHandler, let bestAttemptContent =  bestAttemptContent {
            Pushbots.serviceExtensionTimeWillExpireRequest(self.notificationRequest, with: self.bestAttemptContent)
            contentHandler(bestAttemptContent)
        }
    }

}

Ignore any error till you finish step 2 to import PushBots SDK:
https://www.pushbots.help/install-pushbots-in-your-app-or-website/ios/the-pushbots-part-integrating-pushbots-sdk-into-your-ios-project

----

Flutter SDK additional config:

1. open Podfile, add:

target 'PushbotsNSExtension' do
  Use_frameworks!
  Use_modular_headers!
  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
end

2. choose 'PushbotsNSExtension' target and go to Build Settings then disable Bitcode

3. Finally switch to ios folder in terminal and type pod install