Delete a particular local notification

Question

I am developing an iPhone alarm app based on local notifications.

On deleting an alarm, the related local notification should get cancelled. But how can I determine exactly which object from the array of local notifications is to be cancelled?

I am aware of [[UIApplication sharedApplication] cancelLocalNotification:notification] method but how can I get this 'notification' to cancel it?

Solution 1

You can save a unique value for key in your local notification's userinfo. Get all local notification, loop through the array and delete the particular notification.

Code as follows,

OBJ-C:

UIApplication *app = [UIApplication sharedApplication];
NSArray *eventArray = [app scheduledLocalNotifications];
for (int i=0; i<[eventArray count]; i++)
{
    UILocalNotification* oneEvent = [eventArray objectAtIndex:i];
    NSDictionary *userInfoCurrent = oneEvent.userInfo;
    NSString *uid=[NSString stringWithFormat:@"%@",[userInfoCurrent valueForKey:@"uid"]];
    if ([uid isEqualToString:uidtodelete])
    {
        //Cancelling local notification
        [app cancelLocalNotification:oneEvent];
        break;
    }
}

SWIFT:

var app:UIApplication = UIApplication.sharedApplication()
for oneEvent in app.scheduledLocalNotifications {
    var notification = oneEvent as UILocalNotification
    let userInfoCurrent = notification.userInfo! as [String:AnyObject]
    let uid = userInfoCurrent["uid"]! as String
    if uid == uidtodelete {
        //Cancelling local notification
        app.cancelLocalNotification(notification)
        break;
    }
}

UserNotification:

If you use UserNotification (iOS 10+), just follow this steps:

1. When creating the UserNotification content, add an unique identifier

2. Remove specific pending notification using removePendingNotificationRequests(withIdentifiers:)

3. Remove specific delivered notification using removeDeliveredNotifications(withIdentifiers:)

For more info, UNUserNotificationCenter

Solution 2

Other Option:

First of All, when you create local notification, you can store it in user defaults for future use, Local notification object can not be stored directly in user defaults, This object needs to be converted into NSData object first, and then NSData can be stored into User defaults. Below is code for that:

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:localNotif];
[[NSUserDefaults standardUserDefaults] setObject:data forKey:[NSString  stringWithFormat:@"%d",indexPath.row]];

After you have stored and scheduled local notification, In future, requirement may arise that you need to cancel any of notification that you created earlier, So you can retrieve it from User defaults.

NSData *data= [[NSUserDefaults standardUserDefaults] objectForKey:[NSString   stringWithFormat:@"%d",UniqueKey]];

UILocalNotification *localNotif = [NSKeyedUnarchiver unarchiveObjectWithData:data];
NSLog(@"Remove localnotification  are %@", localNotif);
[[UIApplication sharedApplication] cancelLocalNotification:localNotif];
[[NSUserDefaults standardUserDefaults] removeObjectForKey:[NSString stringWithFormat:@"%d",UniqueKey]];

Hope This helps

Solution 3

Here is what i do.

When creating your notification do this:

  // Create the notification

UILocalNotification *notification = [[UILocalNotification alloc]  init] ;



notification.fireDate = alertDate;
notification.timeZone = [NSTimeZone localTimeZone] ;
notification.alertAction = NSLocalizedString(@"Start", @"Start");
notification.alertBody = **notificationTitle**;
notification.repeatInterval= NSMinuteCalendarUnit;

notification.soundName=UILocalNotificationDefaultSoundName;
notification.applicationIconBadgeNumber = 1;

[[UIApplication sharedApplication] scheduleLocalNotification:notification] ;

when trying to delete it do this:

 NSArray *arrayOfLocalNotifications = [[UIApplication sharedApplication] scheduledLocalNotifications] ;

for (UILocalNotification *localNotification in arrayOfLocalNotifications) {

    if ([localNotification.alertBody isEqualToString:savedTitle]) {
        NSLog(@"the notification this is canceld is %@", localNotification.alertBody);

        [[UIApplication sharedApplication] cancelLocalNotification:localNotification] ; // delete the notification from the system

    }

}

This solution should work for multiple notifications, and your not managing any arrays or dictionaries or user defaults. Your simply using the data you've already saved to the systems notification database.

Hope this helps future designers and developers.

Happy coding guys! :D

Solution 4

Scheduling and removeNotification in swift:

    static func scheduleNotification(notificationTitle:String, objectId:String) {

    var localNotification = UILocalNotification()
    localNotification.fireDate = NSDate(timeIntervalSinceNow: 24*60*60)
    localNotification.alertBody = notificationTitle
    localNotification.timeZone = NSTimeZone.defaultTimeZone()
    localNotification.applicationIconBadgeNumber = 1
    //play a sound
    localNotification.soundName = UILocalNotificationDefaultSoundName;
    localNotification.alertAction = "View"
    var infoDict :  Dictionary<String,String!> = ["objectId" : objectId]
    localNotification.userInfo = infoDict;

    UIApplication.sharedApplication().scheduleLocalNotification(localNotification)
}
    static func removeNotification(objectId:String) {
    var app:UIApplication = UIApplication.sharedApplication()

    for event in app.scheduledLocalNotifications {
        var notification = event as! UILocalNotification
        var userInfo:Dictionary<String,String!> = notification.userInfo as! Dictionary<String,String!>
        var infoDict :  Dictionary = notification.userInfo as! Dictionary<String,String!>
        var notifcationObjectId : String = infoDict["objectId"]!

        if notifcationObjectId == objectId {
            app.cancelLocalNotification(notification)
        }
    }



}

Solution 5

iMOBDEV's solution works perfectly to remove a specific notification (e.g. after deleting the alarm) but it's specially useful when you need to selectively remove any notification that has already fired and is still on the notification center.

A possible scenario would be: the notification for an alarm fires, but the user opens the app without tapping on that notification and schedules that alarm again. If you want to make sure only one notification can be on the notification center for a given item/alarm, it's a good approach. It also allows you not having to clear all notifications every time the app is opened, shall that fit the app better.

• Upon creating a local notification, use NSKeyedArchiver to store it as Data in UserDefaults. You can create a key equal to what you're saving in the notification's userInfo dictionary. If it's associated with a Core Data object, you could use its unique objectID property.
• Retrieve it with NSKeyedUnarchiver. Now you're able to delete it using the cancelLocalNotification method.
• Update the key on UserDefaults accordingly.

Here's a Swift 3.1 version of that solution (for targets below iOS 10):

Store

// localNotification is the UILocalNotification you've just set up
UIApplication.shared.scheduleLocalNotification(localNotification)
let notificationData = NSKeyedArchiver.archivedData(withRootObject: localNotification)
UserDefaults.standard.set(notificationData, forKey: "someKeyChosenByYou")

Retrieve and delete

let userDefaults = UserDefaults.standard
if let existingNotificationData = userDefaults.object(forKey: "someKeyChosenByYou") as? Data,
    let existingNotification = NSKeyedUnarchiver.unarchiveObject(with: existingNotificationData) as? UILocalNotification {

    // Cancel notification if scheduled, delete it from notification center if already delivered    
    UIApplication.shared.cancelLocalNotification(existingNotification)

    // Clean up
    userDefaults.removeObject(forKey: "someKeyChosenByYou")
}

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