Launch a Local Notification at a Specific Time in iOS

Launch a local notification at a specific time in iOS

Well in iOS 10 Apple has deprecated UILocalNotification which means it is time to get familiar with a new notifications framework.

Setup
This is a long post so let’s start easy by importing the new notifications framework:

// Swift
import UserNotifications

// Objective-C (with modules enabled)
@import UserNotifications;

You manage notifications through a shared UNUserNotificationCenter object:

// Swift
let center = UNUserNotificationCenter.current()

// Objective-C
UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];

Authorization
As with the older notifications framework you need to have the user’s permission for the types of notification your App will use. Make the request early in your App life cycle such as in application:didFinishLaunchingWithOptions:. The first time your App requests authorization the system shows the user an alert, after that they can manage the permissions from settings:

// Swift
let options: UNAuthorizationOptions = [.alert, .sound];

// Objective-C
UNAuthorizationOptions options = UNAuthorizationOptionAlert + UNAuthorizationOptionSound;

You make the actual authorization request using the shared notification center:

// Swift
center.requestAuthorization(options: options) { (granted, error) in
    if !granted {
        print("Something went wrong")
    }
}

// Objective-C
[center requestAuthorizationWithOptions:options
completionHandler:^(BOOL granted, NSError * _Nullable error) {
if (!granted) {
NSLog(@"Something went wrong");
}
}];

The framework calls the completion handler with a boolean indicating if the access was granted and an error object which will be nil if no error occurred.

Note: The user can change the notifications settings for your App at any time. You can check the allowed settings with getNotificationSettings. This calls a completion block asynchronously with a UNNotificationSettings object you can use to check the authorization status or the individual notification settings:

 // Swift
 center.getNotificationSettings { (settings) in
     if settings.authorizationStatus != .authorized {
         // Notifications not allowed
     }
 }

 // Objective-C
 [center getNotificationSettingsWithCompletionHandler:^(UNNotificationSettings * _Nonnull settings) {
 if (settings.authorizationStatus != UNAuthorizationStatusAuthorized) {
// Notifications not allowed
 }
 }];

Creating A Notification Request
A UNNotificationRequest notification request contains content and a trigger condition:

Notification Content

The content of a notification is an instance of the UNMutableNotificationContent with the following properties set as required:

title: String containing the primary reason for the alert.

subtitle: String containing an alert subtitle (if required)

body: String containing the alert message text

badge: Number to show on the app’s icon.

sound: A sound to play when the alert is delivered. Use UNNotificationSound.default() or create a custom sound from a file.
launchImageName: name of a launch image to use if your app is launched in response to a notification.

userInfo: A dictionary of custom info to pass in the notification
attachments: An array of UNNotificationAttachment objects. Use to include audio, image or video content.

Note that when localizing the alert strings like the title it is better to use localizedUserNotificationString(forKey:arguments:) which delays loading the localization until the notification is delivered.

A quick example:

 // Swift
 let content = UNMutableNotificationContent()
 content.title = "Don't forget"
 content.body = "Buy some milk"
 content.sound = UNNotificationSound.default()

 // Objective-C
 UNMutableNotificationContent *content = [UNMutableNotificationContent new];
 content.title = @"Don't forget";
 content.body = @"Buy some milk";
 content.sound = [UNNotificationSound defaultSound];

Notification Trigger

Trigger a notification based on time, calendar or location. The trigger can be repeating:

Time interval: Schedule a notification for a number of seconds later. For example to trigger in five minutes:

 // Swift
 let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 300, repeats: false)

 // Objective-C
 UNTimeIntervalNotificationTrigger *trigger =     [UNTimeIntervalNotificationTrigger triggerWithTimeInterval:300
                              repeats:NO];

Calendar: Trigger at a specific date and time. The trigger is created using a date components object which makes it easier for certain repeating intervals. To convert a Date to its date components use the current calendar. For example:

 // Swift
 let date = Date(timeIntervalSinceNow: 3600)
 let triggerDate = Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date)

 // Objective-C
 NSDate *date = [NSDate dateWithTimeIntervalSinceNow:3600];
 NSDateComponents *triggerDate = [[NSCalendar currentCalendar]   
          components:NSCalendarUnitYear +
          NSCalendarUnitMonth + NSCalendarUnitDay +
          NSCalendarUnitHour + NSCalendarUnitMinute +
          NSCalendarUnitSecond fromDate:date];

To create the trigger from the date components:

 // Swift
 let trigger = UNCalendarNotificationTrigger(dateMatching: triggerDate, repeats: false)

 // Objective-C
 UNCalendarNotificationTrigger *trigger = [UNCalendarNotificationTrigger triggerWithDateMatchingComponents:triggerDate
                                     repeats:NO];

To create a trigger that repeats at a certain interval use the correct set of date components. For example, to have the notification repeat daily at the same time we need just the hour, minutes and seconds:

 let triggerDaily = Calendar.current.dateComponents([hour, .minute, .second], from: date)
 let trigger = UNCalendarNotificationTrigger(dateMatching: triggerDaily, repeats: true)

To have it repeat weekly at the same time we also need the weekday:

 let triggerWeekly = Calendar.current.dateComponents([.weekday, .hour, .minute, .second], from: date)
 let trigger = UNCalendarNotificationTrigger(dateMatching: triggerWeekly, repeats: true)

Scheduling

With both the content and trigger ready we create a new notification request and add it to the notification center. Each notification request requires a string identifier for future reference:

 // Swift
 let identifier = "UYLLocalNotification"
 let request = UNNotificationRequest(identifier: identifier, content: content, trigger: trigger)

 center.add(request, withCompletionHandler: { (error) in
     if let error = error {
         // Something went wrong
     }
 })

 // Objective-C
 NSString *identifier = @"UYLLocalNotification";
 UNNotificationRequest *request = [UNNotificationRequest requestWithIdentifier:identifier
                              content:content trigger:trigger]

 [center addNotificationRequest:request withCompletionHandler:^(NSError * _Nullable error) {
  if (error != nil) {
    NSLog(@"Something went wrong: %@",error);
  }
  }];

How do I send local notifications at a specific time in Swift?

This is an example of what I have used for scheduling local notifications using Notification Centre.

let center = UNUserNotificationCenter.current()

let content = UNMutableNotificationContent()
content.title = "My title"
content.body = "Lots of text"
content.sound = UNNotificationSound.default()
content.categoryIdentifier = "yourIdentifier"
content.userInfo = ["example": "information"] // You can retrieve this when displaying notification

// Setup trigger time          
var calendar = Calendar.current
calendar.timeZone = TimeZone.current
let testDate = Date() + 5 // Set this to whatever date you need
let trigger = UNCalendarNotificationTrigger(dateMatching: testDate, repeats: false)

// Create request               
let uniqueID = UUID().uuidString // Keep a record of this if necessary
let request = UNNotificationRequest(identifier: uniqueID, content: content, trigger: trigger)
center.add(request) // Add the notification request

The Date object (represented by testDate above) can be whatever date you want. It is often convenient to create it from DateComponents.

You will need to ask permission for local notifications in the App Delegate at startup to allow this to work. Here is an example.

class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        // Ask permission for notifications
        let center = UNUserNotificationCenter.current()
        center.delegate = self
        center.requestAuthorization(options: [.alert, .badge, .sound]) { (granted, error) in
            if granted {
                print("Permission granted")
            } else {
                print("Permission denied\n")
            }
        }
    }
}

Stop local notification after specific time period

So as per @Paulw11 and @TiranU answer, I scheduled the required number of individual notification. The solution is as follows:-

func localNotificationFire(timeInterval: Int, totalHours: Int) {
    let num = totalHours/timeInterval
    for i in 0..<num {
        let center = UNUserNotificationCenter.current()
        center.delegate = self
        center.requestAuthorization(options: [.alert, .sound]) { (granted, error) in
            // Enable or disable features based on authorization.
            if error != nil {
                print("Request authorization failed!")
            } else {
                print("Request authorization succeeded!")
                
                let content = UNMutableNotificationContent() 
                
                content.title = ""
                content.body = kNotificationReminder
                content.sound = UNNotificationSound.default
                content.badge = 1
                
                let trigger = UNTimeIntervalNotificationTrigger(timeInterval: TimeInterval((i+1)*timeInterval), repeats: false)
                let request = UNNotificationRequest(identifier: "notification.id.\(i)", content: content, trigger: trigger)
                // 4
                UNUserNotificationCenter.current().add(request, withCompletionHandler: nil)
            }
        }
    }
}

Where total hours is the time till I want to trigger the notification and timeInterval is the time gap to trigger a notification.

iOS local notification base on day, time frame and number of times?

If you want to schedule multiple notifications, you need to create multiple notification triggers and register them.

something like:

// Simple extension if you have to create multiple of the same object
extension DateComponents {
   static func triggerFor(hour: Int, minute: Int) -> DateComponents {
      var component = DateComponents()
      component.calendar = Calendar.current
      component.hour = hour
      component.minute = minute
      component.weekday = 1
      return component
   }
}

// Add each trigger into an array with the correct date component
let triggers = [
    UNCalendarNotificationTrigger(dateMatching: DateComponents.triggerFor(hour: 1, minute: 0), repeats: true),
    UNCalendarNotificationTrigger(dateMatching: DateComponents.triggerFor(hour: 2, minute: 0), repeats: true),
    UNCalendarNotificationTrigger(dateMatching: DateComponents.triggerFor(hour: 3, minute: 0), repeats: true),
    UNCalendarNotificationTrigger(dateMatching: DateComponents.triggerFor(hour: 4, minute: 0), repeats: true),
    UNCalendarNotificationTrigger(dateMatching: DateComponents.triggerFor(hour: 5, minute: 0), repeats: true)
]

// Iterate through the array and register the notification with the system
for trigger in triggers {
    // Create the content of the notification
    let content = UNMutableNotificationContent()
    content.title = "My Notification Title"
    content.body = "Body of Notification"

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

    // Schedule the request with the system.
    let notificationCenter = UNUserNotificationCenter.current()
    notificationCenter.add(request) { (error) in
       if error != nil {
          // Handle any errors.
       }
    }
}

UNNotificationRequest to send local notification daily at a specific time

You can use UNCalendarNotificationTrigger for creating a notification that fires repeatedly using UNUserNotificationCenter. You can do something like this. The trick is to only have the time component in the Trigger date.

        let center = UNUserNotificationCenter.current()

        let content = UNMutableNotificationContent()
        content.title = "Attention!"
        content.body = "Your daily alert is ready for you!"
        content.sound = UNNotificationSound.default

        let identifier = "com.yourdomain.notificationIdentifier"

        var triggerDate = DateComponents()
        triggerDate.hour = 18
        triggerDate.minute = 30
        let trigger = UNCalendarNotificationTrigger(dateMatching: triggerDate, repeats: true)

        let request = UNNotificationRequest(identifier: identifier, content: content, trigger: trigger)

        center.add(request, withCompletionHandler: { (error) in
            if let error = error {
                // Something went wrong
                print("Error : \(error.localizedDescription)")
            } else {
                // Something went right
                print("Success")
            }
        })

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