how to cancel a localNotification with the press of a button in swift?

Question

I am scheduling a location based UILocalNotification with the click of a button . But when i try to cancel the localNotification by clicking the same button again, it doesn't cancel the notification. I am using UIApplication.sharedApplication().cancelLocalNotification(localNotification) to cancel my scheduled location based local notification. What am i doing wrong ? here is my implementation

@IBAction func setNotification(sender: UIButton!) {
    if sender.tag == 999 {
        sender.setImage(UIImage(named: "NotificationFilled")!, forState: .Normal)
        sender.tag = 0
        regionMonitor() //function where notification get scheduled

    } else {
        sender.setImage(UIImage(named: "Notification")!, forState: .Normal)
        sender.tag = 999 }

what should i enter into the else block so that the scheduled notification gets canceled. Cannot clear all notifications. here is the didEnterRegion block code where i trigger the local notification

func locationManager(manager: CLLocationManager!, didEnterRegion region: CLRegion!) {
    localNotification.regionTriggersOnce = true
    localNotification.alertBody = "Stack Overflow is great"
    UIApplication.sharedApplication().scheduleLocalNotification(localNotification)
    NSLog("Entering region")
}

Answer 1

You could try to remove all notifications if this is acceptable in your context. Like this:

for notification in UIApplication.sharedApplication().scheduledLocalNotifications as! [UILocalNotification] { 
  UIApplication.sharedApplication().cancelLocalNotification(notification)
}

Or as stated by Logan:

UIApplication.sharedApplication().cancelAllLocalNotifications()

Or as stated by Gerard Grundy for Swift 4:

UNUserNotificationCenter.current().removeAllPendingNotificationRequests()

Answer 2

You can cancel a notification using its identifier :

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

Answer 3

Solution for iOS 10+ Swift 3.1

let center = UNUserNotificationCenter.current()
center.removeAllDeliveredNotifications() // To remove all delivered notifications
center.removeAllPendingNotificationRequests()