Local notifications in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to request permission for local notifications.

iOS Swift

UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound, .badge]) { granted, error in
    if granted {
        print("Permission [1]")
    }
}

Drag options to blanks, or click blank then click option'

Adenied

Bgranted

Crequested

Dpending

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing 'granted' with 'denied'.

Using words unrelated to permission status.

The completion handler returns 'granted' as true when permission is allowed.

2fill in blank

medium

Complete the code to create a notification content with a title.

iOS Swift

let content = UNMutableNotificationContent()
content.[1] = "Hello!"

Drag options to blanks, or click blank then click option'

Atitle

Bbody

Csubtitle

Dsound

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'body' instead of 'title' for the main heading.

Confusing 'subtitle' with 'title'.

The 'title' property sets the main title of the notification.

3fill in blank

hard

Fix the error in the code to schedule a notification after 5 seconds.

iOS Swift

let trigger = UNTimeIntervalNotificationTrigger(timeInterval: [1], repeats: false)
let request = UNNotificationRequest(identifier: "test", content: content, trigger: trigger)
UNUserNotificationCenter.current().add(request)

Drag options to blanks, or click blank then click option'

A5

B-5

C0

D60

Attempts:

3 left

💡 Hint

Common Mistakes

Using zero or negative values causes errors.

Using too large a number delays notification too long.

The timeInterval must be a positive number; 5 seconds schedules the notification correctly.

4fill in blank

hard

Fill both blanks to create a notification with a badge number and sound.

iOS Swift

content.[1] = 1
content.[2] = UNNotificationSound.default

Drag options to blanks, or click blank then click option'

Abadge

Btitle

Csound

Dbody

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing 'title' or 'body' with badge or sound properties.

Using wrong property names for badge or sound.

The 'badge' property sets the app icon badge number, and 'sound' sets the notification sound.

5fill in blank

hard

Fill all three blanks to create and schedule a notification with a 10-second delay and a custom identifier.

iOS Swift

let content = UNMutableNotificationContent()
content.title = "Reminder"
let trigger = UNTimeIntervalNotificationTrigger(timeInterval: [1], repeats: [2])
let request = UNNotificationRequest(identifier: [3], content: content, trigger: trigger)
UNUserNotificationCenter.current().add(request)

Drag options to blanks, or click blank then click option'

Afalse

B10

C"reminder_01"

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Setting repeats to true causes repeated notifications.

Using a number instead of a string for identifier.

Using wrong time interval values.

The time interval is 10 seconds, repeats is false to avoid repeating, and the identifier is a string to identify the notification.

Practice

1. What is the first step you must do before scheduling local notifications in an iOS app?

easy

A. Request permission from the user to send notifications

B. Create the notification content

C. Set up the notification trigger

D. Register the notification category

Solution

1. Step 1: Understand user permission requirement

   iOS requires apps to ask users for permission before sending notifications to respect privacy.

2. Step 2: Request permission before scheduling

   You must call the requestAuthorization method to get user consent before scheduling any notifications.

3. Final Answer:

   Request permission from the user to send notifications -> Option A

4. Quick Check:

   Permission request = Request permission from the user to send notifications [OK]

Hint: Always ask user permission first before notifications [OK]

Common Mistakes:

• Scheduling notifications without permission
• Assuming notifications work without user consent
• Skipping the requestAuthorization call

2. Which of the following is the correct way to create a notification content in Swift?

easy

A. let content = UNNotificationContent()

B. let content = NotificationContent()

C. let content = UNMutableNotificationContent()

D. let content = UNNotificationRequest()

Solution

1. Step 1: Identify the correct class for notification content

   UNMutableNotificationContent is the class used to create and customize notification content.

2. Step 2: Differentiate from other classes

   UNNotificationContent is abstract and cannot be instantiated; UNNotificationRequest is for scheduling, not content.

3. Final Answer:

   let content = UNMutableNotificationContent() -> Option C

4. Quick Check:

   Use UNMutableNotificationContent() to create content [OK]

Hint: Use UNMutableNotificationContent() to create notification content [OK]

Common Mistakes:

• Trying to instantiate UNNotificationContent directly
• Confusing UNNotificationRequest with content
• Using wrong class names

3. What will happen when this Swift code runs?

let content = UNMutableNotificationContent()
content.title = "Reminder"
content.body = "Time to drink water"
let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 5, repeats: false)
let request = UNNotificationRequest(identifier: "waterReminder", content: content, trigger: trigger)
UNUserNotificationCenter.current().add(request)

medium

A. A notification appears after 5 seconds with the given title and body

B. A notification titled 'Reminder' appears immediately

C. The notification repeats every 5 seconds

D. No notification appears because repeats is false

Solution

1. Step 1: Analyze the trigger setup

   The trigger is set with timeInterval 5 seconds and repeats false, so it fires once after 5 seconds.

2. Step 2: Understand notification scheduling

   The request is added to the notification center, so the notification will appear after the delay with the specified title and body.

3. Final Answer:

   A notification appears after 5 seconds with the given title and body -> Option A

4. Quick Check:

   TimeInterval trigger fires once after delay = A notification appears after 5 seconds with the given title and body [OK]

Hint: TimeInterval triggers fire after delay, repeats false means one-time [OK]

Common Mistakes:

• Thinking repeats false means no notification
• Assuming notification appears immediately
• Confusing repeats true with repeats false behavior

4. Identify the error in this Swift code for scheduling a local notification:

let content = UNMutableNotificationContent()
content.title = "Alert"
let trigger = UNTimeIntervalNotificationTrigger(timeInterval: -10, repeats: false)
let request = UNNotificationRequest(identifier: "alert1", content: content, trigger: trigger)
UNUserNotificationCenter.current().add(request)

medium

A. Missing requestAuthorization call before scheduling

B. Negative timeInterval causes an error; timeInterval must be positive

C. content.title should be content.body

D. UNNotificationRequest identifier must be unique

Solution

1. Step 1: Check the trigger timeInterval value

   The timeInterval is set to -10, which is invalid because it must be positive.

2. Step 2: Understand trigger constraints

   UNTimeIntervalNotificationTrigger requires a positive timeInterval to schedule the notification correctly.

3. Final Answer:

   Negative timeInterval causes an error; timeInterval must be positive -> Option B

4. Quick Check:

   timeInterval > 0 required = Negative timeInterval causes an error; timeInterval must be positive [OK]

Hint: timeInterval must be positive for triggers [OK]

Common Mistakes:

• Using negative or zero timeInterval
• Ignoring permission request (though important, not error here)
• Confusing title and body properties

5. You want to schedule a daily local notification at 8:00 AM that repeats every day. Which trigger setup is correct in Swift?

hard

A. UNTimeIntervalNotificationTrigger(timeInterval: 86400, repeats: true)

B. UNTimeIntervalNotificationTrigger(timeInterval: 3600, repeats: true)

C. UNCalendarNotificationTrigger(dateMatching: DateComponents(hour: 8, minute: 0), repeats: false)

D. UNCalendarNotificationTrigger(dateMatching: DateComponents(hour: 8, minute: 0), repeats: true)

Solution

1. Step 1: Understand daily repeating notification needs

   To trigger at a specific time daily, use UNCalendarNotificationTrigger with repeats true and matching hour and minute.

2. Step 2: Compare options

   UNTimeIntervalNotificationTrigger(timeInterval: 86400, repeats: true) repeats every 86400 seconds but may drift; UNCalendarNotificationTrigger(dateMatching: DateComponents(hour: 8, minute: 0), repeats: true) correctly uses calendar components for 8:00 AM daily; UNCalendarNotificationTrigger(dateMatching: DateComponents(hour: 8, minute: 0), repeats: false) does not repeat; UNTimeIntervalNotificationTrigger(timeInterval: 3600, repeats: true) repeats every hour, not daily.

3. Final Answer:

   UNCalendarNotificationTrigger(dateMatching: DateComponents(hour: 8, minute: 0), repeats: true) -> Option D

4. Quick Check:

   Use calendar trigger with repeats true for daily time [OK]

Hint: Use calendar trigger with repeats true for daily notifications [OK]

Common Mistakes:

• Using time interval triggers for exact daily time
• Setting repeats false for repeating notifications
• Confusing seconds with hours in timeInterval