Swift Framework Local Notifications

Main Idea

We use local notification to remind users about the app activity in the background/lockscreen. It consist of content, trigger, and uuid.

OK, that’s our set up complete so let’s turn our focus to the first of two important pieces of work: requesting authorization to show alerts. Notifications can take a variety of forms, but the most common thing to do is ask for permission to show alerts, badges, and sounds – that doesn’t mean we need to use all of them at the same time, but by asking permission up front means we can be selective later on.

If the user grants permission, then we’re all clear to start scheduling notifications. Even though notifications might seem simple, Apple breaks them down into three parts to give it maximum flexibility:

1. The content is what should be shown, and can be a title, subtitle, sound, image, and so on.
2. The trigger determines when the notification should be shown, and can be a number of seconds from now, a date and time in the future, or a location.
3. The request combines the content and trigger, but also adds a unique identifier so you can edit or remove specific alerts later on. If you don’t want to edit or remove stuff, use UUID().uuidString to get a random identifier.

import SwiftUI
import UserNotifications

struct ContentView: View {
    
    var body: some View {
        VStack {
            Button("Request Permission") {
                UNUserNotificationCenter.current().requestAuthorization(options: [.alert,.badge,.sound]) { success, error in
                    if success {
                        print("All set!")
                    } else if let error = error {
                        print(error.localizedDescription)
                    }
                }
            }
            
            Button("Schedule Notification") {
                let content = UNMutableNotificationContent()
                content.title = "Feed the dog"
                content.subtitle = "It looks hungry"
                content.sound = UNNotificationSound.default
                
                let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 5, repeats: false)
                
                let request = UNNotificationRequest(identifier: UUID().uuidString, content: content, trigger: trigger)
                
                UNUserNotificationCenter.current().add(request)
            }
        }
    }
}