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?

Answer 1

swift 3-style:

final private func cancelLocalNotificationsIfIOS9(){


//UIApplication.shared.cancelAllLocalNotifications()
let app = UIApplication.shared
guard let notifs = app.scheduledLocalNotifications else{
    return
}

for oneEvent in notifs {
    let notification = oneEvent as UILocalNotification
    if let userInfoCurrent = notification.userInfo as? [String:AnyObject], let uid = userInfoCurrent["uid"] as? String{
        if uid == uidtodelete {
            //Cancelling local notification
            app.cancelLocalNotification(notification)
            break;
        }
    }
}

}

for iOS 10 use:

    let center = UNUserNotificationCenter.current()
    center.removePendingNotificationRequests(withIdentifiers: [uidtodelete])

Answer 2

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

Answer 3

Swift 4 solution:

UNUserNotificationCenter.current().getPendingNotificationRequests { (requests) in
        for request in requests{
            if request.content.categoryIdentifier == "identifier"{
               UNUserNotificationCenter.current().removePendingNotificationRequests(withIdentifiers: ["identifier"])
            }
        }
    }   

Answer 4

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

Answer 5

For Repeated Reminders ( For example you want your alarm to fire on Sun, Sat and Wed at 4 PM , Then you have to make 3 alarms and set repeatInterval to NSWeekCalendarUnit ).

For making Once Only Reminder :

UILocalNotification *aNotification = [[UILocalNotification alloc] init];
                aNotification.timeZone = [NSTimeZone defaultTimeZone];
                aNotification.alertBody = _reminderTitle.text;
                aNotification.alertAction = @"Show me!";
                aNotification.soundName = UILocalNotificationDefaultSoundName;
                aNotification.applicationIconBadgeNumber += 1;

                NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
                NSDateComponents *componentsForFireDate = [calendar components:(NSYearCalendarUnit | NSWeekCalendarUnit|  NSHourCalendarUnit | NSMinuteCalendarUnit| NSSecondCalendarUnit | NSWeekdayCalendarUnit) fromDate: _reminderDate];

                [componentsForFireDate setHour: [componentsForFireDate hour]] ; //for fixing 8PM hour
                [componentsForFireDate setMinute:[componentsForFireDate minute]];

                [componentsForFireDate setSecond:0] ;
                NSDate *fireDateOfNotification = [calendar dateFromComponents: componentsForFireDate];
                aNotification.fireDate = fireDateOfNotification;
                NSDictionary *infoDict = [NSDictionary dictionaryWithObject:_reminderTitle.text forKey:kRemindMeNotificationDataKey];
                aNotification.userInfo = infoDict;

                [[UIApplication sharedApplication] scheduleLocalNotification:aNotification];

For Making Repeated Reminder :

for (int i = 0 ; i <reminderDaysArr.count; i++)
                {

                    UILocalNotification *aNotification = [[UILocalNotification alloc] init];
                    aNotification.timeZone = [NSTimeZone defaultTimeZone];
                    aNotification.alertBody = _reminderTitle.text;
                    aNotification.alertAction = @"Show me!";
                    aNotification.soundName = UILocalNotificationDefaultSoundName;
                    aNotification.applicationIconBadgeNumber += 1;

                    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
                    NSDateComponents *componentsForFireDate = [calendar components:(NSYearCalendarUnit | NSWeekCalendarUnit|  NSHourCalendarUnit | NSMinuteCalendarUnit| NSSecondCalendarUnit | NSWeekdayCalendarUnit) fromDate: _reminderDate];


                    [componentsForFireDate setWeekday: [[reminderDaysArr objectAtIndex:i]integerValue]];

                    [componentsForFireDate setHour: [componentsForFireDate hour]] ; // Setup Your Own Time.
                    [componentsForFireDate setMinute:[componentsForFireDate minute]];

                    [componentsForFireDate setSecond:0] ;
                    NSDate *fireDateOfNotification = [calendar dateFromComponents: componentsForFireDate];
                    aNotification.fireDate = fireDateOfNotification;
                    aNotification.repeatInterval = NSWeekCalendarUnit;
                    NSDictionary *infoDict = [NSDictionary dictionaryWithObject:_reminderTitle.text forKey:kRemindMeNotificationDataKey];
                    aNotification.userInfo = infoDict;

                    [[UIApplication sharedApplication] scheduleLocalNotification:aNotification];
                }
            }

For Filtering you array to display it.

-(void)filterNotficationsArray:(NSMutableArray*) notificationArray{

    _dataArray = [[NSMutableArray alloc]initWithArray:[[UIApplication sharedApplication] scheduledLocalNotifications]];
    NSMutableArray *uniqueArray = [NSMutableArray array];
    NSMutableSet *names = [NSMutableSet set];

    for (int i = 0 ; i<_dataArray.count; i++) {
        UILocalNotification *localNotification = [_dataArray objectAtIndex:i];
        NSString * infoDict = [localNotification.userInfo objectForKey:@"kRemindMeNotificationDataKey"];

        if (![names containsObject:infoDict]) {
            [uniqueArray addObject:localNotification];
            [names addObject:infoDict];
        }
    }
    _dataArray = uniqueArray;
}

To remove Reminder even it was Once Only or Repeated :

- (void) removereminder:(UILocalNotification*)notification
{
    _dataArray = [[NSMutableArray alloc]initWithArray:[[UIApplication sharedApplication]scheduledLocalNotifications]];

    NSString * idToDelete = [notification.userInfo objectForKey:@"kRemindMeNotificationDataKey"];
    for (int i = 0 ; i<_dataArray.count; i++)
    {
        UILocalNotification *currentLocalNotification = [_dataArray objectAtIndex:i];
        NSString * notificationId = [currentLocalNotification.userInfo objectForKey:@"kRemindMeNotificationDataKey"];

        if ([notificationId isEqualToString:idToDelete])
            [[UIApplication sharedApplication]cancelLocalNotification:currentLocalNotification];
    }

    _dataArray = [[NSMutableArray alloc]initWithArray:[[UIApplication sharedApplication]scheduledLocalNotifications]];
    [self filterNotficationsArray:_dataArray];
    [_remindersTV reloadData];

}

Answer 6

You can keep a string with the category identifier when scheduling the notification like so

        localNotification.category = NotificationHelper.categoryIdentifier

and search for it and cancel when needed like so

let  app = UIApplication.sharedApplication()

    for notification in app.scheduledLocalNotifications! {
        if let cat = notification.category{
            if cat==NotificationHelper.categoryIdentifier {
                app.cancelLocalNotification(notification)
                break
            }

        }
    }