Ytukyg

I have a method below called createNotifications() in which I try to do some fancy stuff when the recurrence of an alarm is daily. I first call self.createNotificationForToday(), which goes fine, and then start a while loop and call self.createNotificationForTomorrowAndReturnNewDateComponents() in each iteration, each time returning the new date components and using it as the input for the next iteration. This allows me to call one method each time and every time, iterate to "tomorrow" and create a notification for that day. The problem is with this part:

var newDateComponents = dateComponents

while numberOfCreatableNotifications > 0 {

    guard var newDateComponents = self.createNotificationForTomorrowAndReturnNewDateComponents(dateComponents: newDateComponents) else {

         os_log("Could not unwrap newDateComponents in createNotifications() in Alarm.swift", log: OSLog.default, type: .debug)

         return

    }

    numberOfCreatableNotifications = numberOfCreatableNotifications - 1

}

What I'm attempting to do is reinitialize the newDateComponents variable each time I go through the while loop and call the createNotificationForTomorrowAnd...() method, and use those newDateComponents as input for the next call to that method. Is there something fundamentally wrong with how I'm trying to do this? Is there a better way?

createNotifications():

private func createNotifications(dateComponents: DateComponents) {



    if recurrence == .today {

        createNotificationForToday(dateComponents: dateComponents)

    } else if recurrence == .tomorrow {

        let _ = createNotificationForTomorrowAndReturnNewDateComponents(dateComponents: dateComponents)

    } else if recurrence == .daily {

        let center = UNUserNotificationCenter.current()

        center.getPendingNotificationRequests { (notifications) in

            var numberOfCreatableNotifications = 64 - notifications.count

            self.createNotificationForToday(dateComponents: dateComponents)

            var newDateComponents = dateComponents

            while numberOfCreatableNotifications > 0 {

                guard var newDateComponents =

                        self.createNotificationForTomorrowAndReturnNewDateComponents(dateComponents: newDateComponents) else {

                    os_log("Could not unwrap newDateComponents in createNotifications() in Alarm.swift", log: OSLog.default, type: .debug)

                    return

                }

                numberOfCreatableNotifications = numberOfCreatableNotifications - 1

            }

        }

    } else {}



}

createNotificationForToday():

private func createNotificationForToday(dateComponents: DateComponents) {



    let center = UNUserNotificationCenter.current()



    let content = UNMutableNotificationContent()

    content.title = "Random Alarm"

    content.subtitle = "It's time!"

    content.body = self.note

    content.sound = UNNotificationSound.default



    let trigger = UNCalendarNotificationTrigger(dateMatching: dateComponents, repeats: false)



    let uuidString = UUID().uuidString

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



    center.add(request) { (error) in

        if error != nil {

            print("error (String(describing: error))")

        }

    }



}

createNotificationForTomorrowAndReturnNewDateComponents():

private func createNotificationForTomorrowAndReturnNewDateComponents(dateComponents: DateComponents) -> DateComponents? {



    let center = UNUserNotificationCenter.current()



    let content = UNMutableNotificationContent()

    content.title = "Random Alarm"

    content.subtitle = "It's time!"

    content.body = self.note

    content.sound = UNNotificationSound.default



    let calendar = Calendar.current

    guard let date = calendar.date(from: dateComponents) else {

        os_log("Could not unwrap date in createNotificationForTomorrow() in Alarm.swift", log: OSLog.default, type: .debug)

        return nil

    }

    guard let tomorrow = calendar.date(byAdding: .day, value: 1, to: date) else {

        os_log("Could not unwrap tomorrow in createNotificationForTomorrow() in Alarm.swift", log: OSLog.default, type: .debug)

        return nil

    }

    let newDateComponents = calendar.dateComponents([.year, .month, .day, .timeZone, .hour, .minute], from: tomorrow)



    let trigger = UNCalendarNotificationTrigger(dateMatching: newDateComponents, repeats: false)



    let uuidString = UUID().uuidString

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



    center.add(request) { (error) in

        if error != nil {

            print("error (String(describing: error))")

        }

    }



    return newDateComponents



}

The scope of a variable created by a guard statement is the block that contains the guard statement, which is the body of your while loop.

This means that the newDateComponents you are creating with your guard statement is not the same as the newDateComponents you created outside the while and the inner newDateComponents will be discarded after each iteration of the while loop.

You don't actually need the guard statement; you can build the unwrap into your while:

var newDateComponents: DateComponents? = dateComponents

while numberOfCreatableNotifications > 0, let currentDateComponents = newDateComponents {

    newDateComponents = self.createNotificationForTomorrowAndReturnNewDateComponents(dateComponents: currentDateComponents) 

    numberOfCreatableNotifications -= 1

}

if numberOfCreateableNotifications > 0 {

    os_log("Could not create all notifications

}

You can probably refactor this to be a bit more efficient and have one less function:

• Use a Calendar property so that you don't need to keep instantiating the calendar


• Have a function to return "tomorrow"


• Have a function to schedule a notification

let calendar = Calendar.autoUpdatingCurrent



private func createNotifications(dateComponents: DateComponents) {



    switch (recurrence) {

        case .today:

            createNotification(for: dateComponents)

        case .tomorrow:

            createNotification(for: day(after: dateComponents))

        case .daily:

           let center = UNUserNotificationCenter.current()

           center.getPendingNotificationRequests { (notifications) in

               var numberOfCreatableNotifications = 64 - notifications.count

               var currentDay: DateComponents? = dateComponents

               while numberOfCreatableNotifications > 0, current = currentDay {

                   createNotification(for: current)

                   currentDay = day(after: current)

                   numberOfCreateableNotification -= 1

               }  

               if numberOfCreateableNotifications > 0 {

                   os_log("Could not create all notifications", type: .debug)

               }

            }                          

    }

}





private func createNotification(for dateComponents: DateComponents) {



    let center = UNUserNotificationCenter.current()



    let content = UNMutableNotificationContent()

    content.title = "Random Alarm"

    content.subtitle = "It's time!"

    content.body = self.note

    content.sound = UNNotificationSound.default



    let trigger = UNCalendarNotificationTrigger(dateMatching: dateComponents, repeats: false)



    let uuidString = UUID().uuidString

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



    center.add(request) { (error) in

        if let err = error {

            print("error (err.localizedDescription)")

        }

    }

}







private func day(after dateComponents: DateComponents) -> DateComponents? {



    guard let date = calendar.date(from: dateComponents), 

          let tomorrow = calendar.date(byAdding: .day, value: 1, to: date)

    else {

        os_log("Could not calculate tomorrow in Alarm.swift", log: OSLog.default, type: .debug)

        return nil

    }

    let newDateComponents = calendar.dateComponents([.year, .month, .day, .timeZone, .hour, .minute], from: tomorrow)

    return newDateComponents



}

One final note, it would probably be nicer to pass Date instances rather than DateComponent instances and convert to DateComponent once when you need to actually schedule the notification.

You cannot directly bind to the variable newDateComponents from the
outer scope in the guard-statement. You can bind to a new variable and
then assign that to newDateComponents:

var newDateComponents = dateComponents

while numberOfCreatableNotifications > 0 {

    guard let nextDateComponents =

        self.createNotificationForTomorrowAndReturnNewDateComponents(dateComponents: newDateComponents) else {

            os_log("Could not unwrap newDateComponents in createNotifications() in Alarm.swift", log: OSLog.default, type: .debug)

            return

    }

    newDateComponents = nextDateComponents

    numberOfCreatableNotifications = numberOfCreatableNotifications - 1

}