Top iOS Interview Questions and Answers

Here are top iOS interview questions,

1. What is the iOS operating system?

iOS is Apple's mobile operating system that powers iPhones, iPads, and iPod Touch devices.

 

2. Explain the key features of iOS.

Key features of iOS include a user-friendly interface, app security, regular updates, integration with Apple services, and a vast app ecosystem.

 

3. What is the difference between iOS and Android operating systems?

iOS is developed by Apple and exclusively runs on Apple devices, while Android is developed by Google and is available on various devices from different manufacturers. iOS has a more closed ecosystem, whereas Android is more open-source.

 

4. What is the significance of the Core Data framework?

Core Data is Apple's object graph management and persistence framework. It allows developers to manage data models and perform database operations efficiently.

 

5. Explain the role of the AppDelegate class in an iOS app.

The AppDelegate class handles app-level events and manages the app's overall life cycle, responding to events like app launch, termination, and handling push notifications.

 

6. What is the purpose of Interface Builder in Xcode?

Interface Builder is a visual design tool in Xcode that allows developers to design user interfaces for iOS apps using a drag-and-drop approach, without writing code manually.

 

7. What are the different multitasking mechanisms in iOS?

iOS supports various multitasking mechanisms, such as background execution, background fetch, and push notifications to keep apps responsive even when not in the foreground.

 

8. What is the difference between retain, strong, weak, and unowned references in iOS memory management?

These are reference attributes used in Automatic Reference Counting (ARC) for memory management. Retain and strong are synonyms, while weak creates a non-retaining reference, and unowned is used for non-optional references that don't increase the retain count.

 

9. Explain the significance of CoreData and CloudKit synchronization.

CoreData and CloudKit synchronization allow apps to store and manage data locally using CoreData while syncing that data with iCloud using CloudKit, providing seamless data sharing across multiple devices.

 

10. What is the purpose of CocoaPods in iOS development?

CocoaPods is a dependency manager for iOS projects, simplifying the integration of third-party libraries and frameworks into an app.

 

11. What are the main steps involved in submitting an iOS app to the App Store?

The main steps include creating an App Store Connect account, preparing the app, creating an archive, submitting the app for review, and managing the release.

 

12. How can you optimize an iOS app for better performance?

Performance optimization techniques include using instruments to profile the app, reducing unnecessary computations, optimizing memory usage, and employing caching mechanisms.

 

13. Explain the concept of Grand Central Dispatch (GCD) in iOS.

Grand Central Dispatch is a concurrency framework that allows developers to perform tasks concurrently and efficiently manage system resources.

 

14. What are App Extensions in iOS?

App Extensions allow developers to extend the functionality of their apps and interact with system services, such as sharing content, providing custom keyboards, and more.

 

15. How does Touch ID and Face ID contribute to iOS security?

Touch ID and Face ID are biometric authentication methods that enhance security by providing a convenient yet secure way to unlock devices and authenticate users.

 

16. What is the purpose of the NotificationCenter class in iOS?

NotificationCenter facilitates communication between different parts of an app by broadcasting and observing notifications.

 

17. Explain the concept of Keychain in iOS.

Keychain is a secure storage mechanism that allows apps to securely store sensitive data like passwords, encryption keys, and certificates.

 

18. What is the role of the Core Animation framework in iOS?

Core Animation is responsible for animating user interfaces and enhancing the visual experience of iOS apps.

 

19. How can you support multiple screen sizes in iOS development?

By using Auto Layout, Size Classes, and Adaptive User Interface design, developers can create apps that adapt to different screen sizes and orientations.

 

20. What is TestFlight, and how does it aid in app testing?

TestFlight is Apple's platform for beta testing iOS apps, allowing developers to distribute pre-release versions of their apps to testers for feedback and bug testing before the official release.

 

Above are few top iOS interview questions. Remember to prepare and expand on these answers.

Good luck with your interview!  👍