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Overview

With the introduction of iOS 10, rich push notifications have made their way into the iOS ecosystem. This exciting feature allows you to enhance your push notifications by incorporating engaging multimedia elements such as images, videos, audio, or GIFs. Rich push notifications offer a convenient way to provide users with quick interactions that don’t require them to launch the entire app. This highlights the increasing significance of notifications in shaping an app’s overall user experience. Rich push notifications leverage the power of Notification Service and Notification Content extensions to enrich the user experience. These extensions are separate and unique components embedded within your app bundle.

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Enabling Rich Push Notification support

When a new push notification arrives, the system first invokes your notification service extension to customize the payload and include media attachments for display. The notification content extension comes into play by providing a custom interface to present your app’s notifications in a visually appealing and interactive manner. Together, these extensions work seamlessly to deliver captivating and dynamic push notifications to your app’s users.

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Adding Notification Service Extension

Step 1: Adding the Notification Service Extension to your Xcode Project
  1. Open your Xcode project.
  2. Go to File -> New -> Target.
  3. Select “Notification Service Extension” under the “iOS” category.
  4. Click “Next” and provide a name for your extension (e.g., “MyNotificationServiceExtension”).
  5. Choose the appropriate settings for your extension and click “Finish”.
  6. Xcode will generate the necessary files for the Notification Service Extension.
Step 2: Importing the CastledNotificationService Framework Import the CastledNotificationService framework by adding the below entry in the Podfile 
target 'YourNotificationServiceExtension' do
  use_frameworks!
   pod 'CastledNotificationService'
end
Step 3: Set the App Group ID 3.1 First, set the App Groups for the main target by referring here. 3.2 Enable App Groups for your notification service extension target and use the same App Group ID that was selected for the app target (as mentioned in the previous steps). Step 4: Implementing the Notification Service Extension In your Notification Service Extension code file, inherit from the CastledNotificationServiceExtension class provided by the CastledNotificationService framework. Customize the notification handling logic in the overridden methods of MyNotificationServiceExtension class. Override the didReceive(_:withContentHandler:) method to modify the notification content if needed. Override the serviceExtensionTimeWillExpire() method to handle situations when the service extension time is about to expire. 
import UserNotifications
import CastledNotificationService

class NotificationService: CastledNotificationServiceExtension {

    override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
        appGroupId = "<your_app_group_id>"
        //calling super to make sure Castled implementation is called.
        super.didReceive(request, withContentHandler: contentHandler)
    }

    override func serviceExtensionTimeWillExpire() {
        // This method is called right before the extension is terminated by the system.
        // Take this opportunity to provide your "best attempt" at modified content.
        // If you don't make any changes, the original push payload will be used by default.
        if let contentHandler = contentHandler, let bestAttemptContent =  bestAttemptContent {           
            contentHandler(bestAttemptContent)         
        }     
    }   
}
Please refer to the official Apple documentation for further details on working with Notification Service Extensions

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Adding Notification Content Extension

Step 1: Adding the Notification Content Extension to your Xcode Project
  1. Open your Xcode project.
  2. Go to File -> New -> Target.
  3. Select “Notification Content Extension” under the “iOS” category.
  4. Click “Next” and provide a name for your extension (e.g., “MyNotificationContent”).
  5. Choose the appropriate settings for your extension and click “Finish”.
  6. Xcode will generate the necessary files for the Notification Service Extension.
Step 2: Configuring the Info.plist File
  1. Open the Info.plist file of your Notification Content Extension target.
  2. Add the following key-value pair:
KeyValue
UNNotificationExtensionCategoryCASTLED_PUSH_TEMPLATE
UNNotificationExtensionInitialContentSizeRatio1
UNNotificationExtensionDefaultContentHiddenYES
UNNotificationExtensionUserInteractionEnabledYES
Configure the Notification Categories & actions and use the same for configuring UNNotificationExtensionCategory. The required categories can be added as an array.
Step 3: Importing the CastledNotificationContent Framework Import the CastledNotificationContent framework by adding the below entry in the Podfile 
target 'YourNotificationContentExtension' do
  use_frameworks!
   pod 'CastledNotificationContent'
end
Step 4: Set the App Group ID 4.1 First, set the App Groups for the main target by referring here. 4.2 Enable App Groups for your notification content extension target and use the same App Group ID that was selected for the app target (as mentioned in the previous steps). Step 5: Implementing the Notification Content Extension In your NotificationViewController file, inherit from the CastledNotificationViewController class provided by the CastledNotificationContent framework. Customize the notification handling logic in the overridden methods of NotificationViewController class. Override the viewDidLoad() and didReceive() methods to modify the notification content if needed. 
import UIKit
import Castled
import UserNotifications
import UserNotificationsUI
import CastledNotificationContent

class NotificationViewController: CastledNotificationViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        appGroupId = "<your_app_group_id>"
        // Do any required interface initialization here.
    }
    
    override func didReceive(_ notification: UNNotification) {
        super.didReceive(notification)
    }
    
}