Create, Schedule and Receive Local Notifications in Swift

Time interval notifications are a type of local notification that is scheduled to be delivered after a certain time interval has passed. This is useful when you want to send notifications at specific intervals, such as every hour or every day at a particular time.

To create a time interval notification, you use the UNTimeIntervalNotificationTrigger class, which allows you to specify the time interval from the current time when the notification should be delivered. You can also specify whether the notification should repeat at the specified interval or only fire once.

Here’s an example of how to create a time interval notification that fires after 5 seconds and does not repeat:

func createLocalNotification(title: String, body: String, timeInterval: Double, identifier: String) {
        let notificationCenter = UNUserNotificationCenter.current()
        let content = UNMutableNotificationContent()
        content.title = title
        content.body = body
        content.sound = UNNotificationSound.default
        
        let trigger = UNTimeIntervalNotificationTrigger(timeInterval:  timeInterval, repeats: false)
        let request = UNNotificationRequest(identifier: identifier, content: content, trigger: trigger)
        
        notificationCenter.removeDeliveredNotifications(withIdentifiers: [identifier]) // Remove previous pending notification with same identifier
        
        notificationCenter.add(request) { error in
            if let error = error {
                print("Error scheduling notification: \(error)")
            } else {
                print("Notification \(content.title) added")
            }
        }
    }

createLocalNotification(
                    title: "Publish a tutorial",
                    body: "Don't forget to complete your task",
                    timeInterval: 5, identifier: "DailyTask1" // The time (in seconds))

In this code snippet, you create a UNMutableNotificationContent object to define the content of the notification. Then, you set the UNTimeIntervalNotificationTrigger  to fire the notification after 5 seconds.

Before adding it to the UNUserNotificationCenter to schedule the notification you remove the previous notification with the same identifier using removeDeliveredNotifications(withIdentifiers: [identifier]).

Finally, you create a UNNotificationRequest  with the content and trigger and add it to the UNUserNotificationCenter to schedule the notification.

Time Interval Notifications: Complete Code Example

Below is a complete code example for time interval local notification using SwiftUI.

import SwiftUI
import UserNotifications

struct NotificationView: View {
    
    func requestNotificationAuthorization() {
        let center = UNUserNotificationCenter.current()
        
        center.getNotificationSettings { settings in
            switch settings.authorizationStatus {
            case .notDetermined:
                center.requestAuthorization(options: [.alert, .badge, .sound]) { granted, error in
                    if granted {
                        print("Notification access granted.")
                    } else {
                        print("Notification access denied.\(String(describing: error?.localizedDescription))")
                    }
                }
                return
            case .denied:
                print("Notification access denied")
                return
            case .authorized:
                print("Notification access granted.")
                return
            default:
                return
            }
        }
    }
    
    func createTimeIntervalLocalNotification(title: String, body: String, timeInterval: Double, identifier: String) {
        let notificationCenter = UNUserNotificationCenter.current()
        let content = UNMutableNotificationContent()
        content.title = title
        content.body = body
        content.sound = UNNotificationSound.default
        
        let trigger = UNTimeIntervalNotificationTrigger(timeInterval:  timeInterval, repeats: false)
        let request = UNNotificationRequest(identifier: identifier, content: content, trigger: trigger)
        
        notificationCenter.removeDeliveredNotifications(withIdentifiers: [identifier]) // Remove previous pending notification with same identifier
        
        notificationCenter.add(request) { error in
            if let error = error {
                print("Error scheduling notification: \(error)")
            } else {
                print("Notification \(content.title) added")
            }
        }
    }
    
    var body: some View {
        VStack {
            Button("Request notification permission"){
                requestNotificationAuthorization()
            }
            .buttonStyle(.bordered)
            
            Button("Schedule Notification"){
                createTimeIntervalLocalNotification(
                    title: "Publish a tutorial",
                    body: "Don't forget to complete your task",
                    timeInterval: 5, identifier: "DailyTask1" // The time (in seconds)
                )
                
            }
            .buttonStyle(.bordered)
            
        }
        .padding()
        
    }
}