Push notification integration in HLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Push Notification Tokens

What is the primary purpose of a push notification token in mobile apps?

A It schedules the notification delivery time

B It stores the content of the notification message

C It encrypts the notification data before sending

D It uniquely identifies a device to receive push notifications

💡 Hint

Think about how the server knows where to send the notification.

A push notification token is a unique identifier assigned to a device by the notification service. It tells the server exactly which device should receive the notification.

❓ ui_behavior

intermediate

Notification Permission Request Behavior

When should a mobile app request permission from the user to send push notifications?

A Immediately when the app launches for the first time

B After the user has received at least one notification

C Only after explaining the benefits of notifications to the user

D Only if the user navigates to the settings screen

💡 Hint

Consider user experience and avoiding annoying pop-ups.

Requesting permission after explaining benefits helps users understand why notifications are useful, increasing the chance they allow them.

❓ lifecycle

advanced

Handling Notifications When App is in Background

What happens when a push notification arrives while the app is in the background on a mobile device?

A The notification is shown in the device's notification center without opening the app

B The app automatically opens and displays the notification content

C The notification is ignored until the app is opened again

D The app crashes if it tries to process the notification in the background

💡 Hint

Think about how notifications appear outside the app.

When the app is in the background, the system shows the notification in the notification center. The app does not open automatically.

❓ navigation

advanced

Navigating After Notification Tap

Which approach correctly handles navigation when a user taps a push notification to open the app?

HLD

function onNotificationTap(notification) {
  if (notification.data && notification.data.screen) {
    navigateTo(notification.data.screen);
  } else {
    navigateTo('Home');
  }
}

A Ignore notification data and reload the current screen

B Check notification data for target screen and navigate accordingly

C Always navigate to the Home screen regardless of notification content

D Close the app immediately after tapping the notification

💡 Hint

Think about how to direct users to relevant content from notifications.

Using notification data to decide navigation ensures users see the content related to the notification they tapped.

🔍 Analysis

expert

Debugging Missing Push Notifications

A developer notices users do not receive push notifications on Android devices. Which issue below is the most likely cause?

A The app did not register the device token with the push notification service

B The app uses HTTPS instead of HTTP for sending notifications

C The notification payload is missing the title field

D The app requested notification permission too late after launch

💡 Hint

Without a device token, the server cannot send notifications to the device.

If the device token is not registered, the push service does not know where to send notifications, so users won't receive them.