SwiftUI- Notification

A notification is a message or alert sent to users to inform them of new information, updates, or events related to an application or service. Notifications can appear on a device's lock screen, in the notification center, or as banners or alerts, depending on the system and settings.

Types of Notifications

In SwiftUI, notifications are of two types:

• Local Notifications: These are scheduled and triggered locally on the device without needing an internet connection. For instance, a reminder app might use a local notification to alert a user about an upcoming event.

• Push (Remote) Notifications: These are sent from a server to the device, often through a service like Apple Push Notification Service (APNs) for iOS or Firebase Cloud Messaging (FCM) for Android. For example, a social media app might send a push notification to notify a user about a new message.

How Notification Works?

The working of notification is explained in the following steps:

• Permission Request: Apps request permission from users to show notifications.

• Triggering: A notification is triggered either by the app (local) or a server (push).

• Display: The notification is shown on the device as a banner, sound, or badge.

• Interaction: Users may interact with the notification by tapping it, which opens the app or performs an action (e.g., reply to a message).

Local Notification

A local notification in SwiftUI refers to a notification that is triggered by the app itself, typically without requiring an internet connection. Local notifications can be scheduled to appear at a certain time or after a specific event, and they can include content like titles, messages, sounds, and badges.

These notifications are managed locally on the device, which means the app does not rely on an external server to trigger them.

Example

The following SwiftUI program is used to create local notification.

import SwiftUI
import UserNotifications
@main
struct MyApp: App {
   @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
   var body: some Scene {
     WindowGroup {
       ContentView()
         .onAppear {
            // Request notification permission when the app appears
            requestNotificationPermission()
         }
     }
   }
   // Request permission to show notifications
   func requestNotificationPermission() {
     UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .badge, .sound]) { granted, error in
       if granted {
         print("Notification permission granted")
       } else if let error = error {
         print("Error: \(error.localizedDescription)")
       }
     }
   }
   // Function to schedule a local notification after 5 seconds
   func scheduleLocalNotification() {
     let content = UNMutableNotificationContent()
     content.title = "Reminder!"
     content.body = "This is a local notification from SwiftUI."
     content.sound = .default

     // Trigger the notification 5 seconds later
     let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 5, repeats: false)

     // Create a notification request
     let request = UNNotificationRequest(identifier: UUID().uuidString, content: content, trigger: trigger)

     // Add the notification request to the notification center
     UNUserNotificationCenter.current().add(request) { error in
       if let error = error {
         print("Error scheduling notification: \(error.localizedDescription)")
       } else {
         print("Notification scheduled successfully!")
       }
     }
   }
}
class AppDelegate: NSObject, UIApplicationDelegate, UNUserNotificationCenterDelegate {   
   // This function is called when the app finishes launching
   func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
     UNUserNotificationCenter.current().delegate = self
     return true
   }
   // Handle notification when app is in the foreground
   func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
     // Show the notification with a banner and sound
     completionHandler([.banner, .sound])
   }
}
struct ContentView: View {
   var body: some View {
     VStack {
       Text("Local Notification Example").font(.title).padding()

       // Button to schedule a local notification
       Button(action: {
         // Call the function to schedule the notification
         if let appDelegate = UIApplication.shared.delegate as? AppDelegate {
            appDelegate.scheduleLocalNotification()
         }
       }) {
         Text("Schedule Notification")
            .padding()
            .background(Color.blue)
            .foregroundColor(.white)
            .cornerRadius(10)
       }
     }.padding()
   }
}

Remote Notification

Push (Remote) Notifications are messages sent from a server to a user's device, even when the app is not running in the foreground. Unlike local notifications, which are triggered by the app itself, push notifications are initiated from an external server, typically through services like Apple Push Notification Service (APNs) for iOS and Firebase Cloud Messaging (FCM) for Android.

Example

The following SwiftUI program is used to create push notification.

import SwiftUI
import UserNotifications
import UIKit

@main
struct MyApp: App {
   @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate

   var body: some Scene {
     WindowGroup {
       ContentView()
         .onAppear {
            // Request notification permission on launch
            requestPushNotificationPermission()
         }
      }
   }

   // Request push notification permission
   func requestPushNotificationPermission() {
     UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .badge, .sound]) { granted, error in
       if granted {
         print("Push notification permission granted")
       } else if let error = error {
         print("Error requesting permission: \(error.localizedDescription)")
       }
     }
   }
}
class AppDelegate: NSObject, UIApplicationDelegate {   
   func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
     // Request push notification permission
     requestPushNotificationPermission()
     
     // Register for remote notifications
     application.registerForRemoteNotifications()
     return true
   }
   func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
     // Handle device token here
     let deviceTokenString = deviceToken.map { String(format: "%02x", $0) }.joined()
     print("Device Token: \(deviceTokenString)")
     // Send this device token to your server
   }
   func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
     print("Failed to register for push notifications: \(error.localizedDescription)")
   }
}
extension AppDelegate: UNUserNotificationCenterDelegate {   
   // Handle push notifications in the foreground
   func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
     completionHandler([.banner, .sound, .badge])
   }
   // Handle when the user taps on a notification
   func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
     print("User tapped on the notification: \(response.notification.request.content.body)")
     completionHandler()
   }
}
struct ContentView: View {
   var body: some View {
     VStack {
       Text("Push Notifications Example")
         .font(.title).padding()

       Text("Push notifications will appear here when sent from the server.")
         .padding()

       // Button for testing or interacting with notifications
       Button("Send Test Push Notification") {
         // Trigger server-side action to send a push notification
       }.padding()
       .background(Color.blue)
       .foregroundColor(.white)
       .cornerRadius(10)
     }
   }
}